407-MM-CH62

BHT-407-MM-6

62-00-0016 FEB 2012 Rev. 34 Page 1ECCN EAR99

TABLE OF CONTENTS

Paragraph Chapter/Section Page Number Title Number Number

CHAPTER 62 — MAIN ROTOR

MAIN ROTOR SYSTEM

62-1 Main Rotor System — Description................................................. 62-00-00 562-2 Main Rotor System — Operational Check ..................................... 62-00-00 562-3 Main Rotor System — General Condition and Security

— Inspection .................................................................................. 62-00-00 562-3A Expandable Blade Bolts — 600-Hour or 12-Month Inspection ...... 62-00-00 1462-4 Main Rotor System — Unscheduled Inspections........................... 62-00-00 1962-5 Main Rotor — Hard Landing Inspection.................................... 62-00-00 1962-6 Main Rotor — Sudden Stoppage Inspection ............................ 62-00-00 1762-7 Main Rotor — Overtorque Inspection — After Overtorque

110 to 120%.............................................................................. 62-00-00 1962-8 Main Rotor — Overtorque Inspection — Overtorque Above

120%......................................................................................... 62-00-00 1962-9 Main Rotor — Overspeed Inspection — After Overspeed in

Excess of 118% NR................................................................................... 62-00-00 2062-10 Main Rotor — Lightning Strike Inspection ................................ 62-00-00 2162-11 Main Rotor System — Main Rotor Blade Description .................... 62-00-00 2162-12 Main Rotor Blade — Removal ....................................................... 62-00-00 2362-13 Main Rotor Blade — Cleaning ....................................................... 62-00-00 2562-14 Main Rotor Blade — Normal/Conditional Inspections.................... 62-00-00 2562-15 Main Rotor Blade — Retention Bolt Holes Bushing Liner

— Inspection............................................................................. 62-00-00 2662-16 Main Rotor Blade — Fretting Pads — Inspection ..................... 62-00-00 2662-17 Main Rotor Blade — Root End Closure — Inspection .............. 62-00-00 2662-18 Main Rotor Blade — Trim Tabs — Inspection .......................... 62-00-00 2962-19 Main Rotor Blade — Tooling Key Area (Upper Surface)

— Inspection............................................................................. 62-00-00 2962-20 Main Rotor Blade — Erosion Strip — Inspection...................... 62-00-00 2962-21 Main Rotor Blade — Erosion Shield — Inspection ................... 62-00-00 3062-22 Main Rotor Blade — Upper and Lower Skins — Inspection ..... 62-00-00 3062-23 Main Rotor Blade — Trailing Edge — Inspection ..................... 62-00-00 3162-24 Main Rotor Blade — Tie-down — Inspection............................ 62-00-00 3162-25 Main Rotor Blade — Upper Product Balance Weight Cover

— Inspection............................................................................. 62-00-00 3162-26 Main Rotor Blade — Upper Product Balance Weight

Retainer — Inspection .............................................................. 62-00-00 3162-27 Main Rotor Blade — Lower Product Balance Weight Cover

— Inspection............................................................................. 62-00-00 3262-28 Main Rotor Blade — Upper and Lower Product Balance

Weights — Inspection............................................................... 62-00-00 3262-29 Main Rotor Blade — Upper Product Balance Cover

Threaded Insert — Inspection .................................................. 62-00-00 3262-30 Main Rotor Blade — Repair ........................................................... 62-00-00 3262-31 Main Rotor Blade — Retention Bolt Holes Bushing Liner

— Repair................................................................................... 62-00-00 32

BHT-407-MM-6

62-00-00Page 2 Rev. 34 16 FEB 2012 ECCN EAR99

TABLE OF CONTENTS (CONT)


62-32 Main Rotor Blade — Root End Closure — Repair.................... 62-00-00 3262-33 Main Rotor Blade — Trim Tabs — Repair and Replacement... 62-00-00 3362-34 Main Rotor Blade — Tooling Key Area (Upper Surface)

— Repair................................................................................... 62-00-00 3662-35 Main Rotor Blade — Erosion Strip — Repair............................ 62-00-00 3662-36 Main Rotor Blade — Erosion Shield — Repair ......................... 62-00-00 3862-37 Main Rotor Blade — Upper and Lower Skins — Repair........... 62-00-00 3862-38 Main Rotor Blade — Upper and Lower Skins and Core

— Repair................................................................................... 62-00-00 4262-39 Main Rotor Blade — Trailing Edge — Repair ........................... 62-00-00 4762-40 Main Rotor Blade — Tie-down — Repair ................................. 62-00-00 4762-41 Main Rotor Blade — Upper Product Balance Cover

— Removal/Installation............................................................. 62-00-00 4962-42 Main Rotor Blade Repair — Upper Product Balance Weight

Retainer — Removal/Installation .............................................. 62-00-00 5162-43 Main Rotor Blade Repair — Lower Product Balance Weight

Cover — Removal/Installation .................................................. 62-00-00 5262-43A Main Rotor Blade Repair — Product Balance Fiberglass

Cover — Removal/Installation .................................................. 62-00-00 5362-44 Main Rotor Blade Repair — Upper and Lower Product

Balance Weights — Removal/Installation................................. 62-00-00 5362-45 Main Rotor Blade — Upper Product Balance Cover

Threaded Insert — Repair ........................................................ 62-00-00 5362-46 Main Rotor Blade — Paint Refinishing ..................................... 62-00-00 5462-47 Main Rotor Blade — Polyurethane Protective Tape ................. 62-00-00 5662-47A Polyurethane Protective Tape — Cleaning and

Surface Preparation .......................................................... 62-00-00 5662-47B Polyurethane Protective Tape — Wet Application

Method .............................................................................. 62-00-00 5662-47C Polyurethane Protective Tape — Dry Application

Method .............................................................................. 62-00-00 5762-47D Polyurethane Protective Tape — Inspection..................... 62-00-00 5762-47E Polyurethane Protective Tape — Edge Sealing

(Optional) .......................................................................... 62-00-00 5762-47F Polyurethane Protective Tape — Removal....................... 62-00-00 5762-48 Main Rotor Blade — Installation .................................................... 62-00-00 5862-49 Main Rotor System — Frahm Assembly........................................ 62-00-00 5962-50 Frahm Assembly — Condition and Security — Inspection ....... 62-00-00 5962-51 Frahm Assembly — Removal ................................................... 62-00-00 5962-52 Frahm Assembly — Cleaning ................................................... 62-00-00 6362-53 Frahm Assembly — Disassembly............................................. 62-00-00 6362-54 Frahm Assembly — Inspection................................................. 62-00-00 6762-55 Frahm Assembly — Repair....................................................... 62-00-00 8362-56 Frahm Assembly — Assembly.................................................. 62-00-00 8762-57 Frahm Assembly — Installation ................................................ 62-00-00 9062-58 Main Rotor System — Main Rotor Hub Assembly ......................... 62-00-00 9062-59 Main Rotor Hub Assembly — Removal .................................... 62-00-00 9162-60 Main Rotor Hub Assembly — Assembly/Disassembly ............. 62-00-00 10262-61 Main Rotor Hub Assembly — Inspection and Repair ............... 62-00-00 102

BHT-407-MM-6

62-00-0010 DEC 2012 Rev. 35 Page 3Export Classification C, ECCN EAR99

TABLE OF CONTENTS (CONT)


62-62 Main Rotor Hub Assembly — (S/N 53000 through 53066Pre TB 407-99-16) — Installation ............................................. 62-00-00 114

62-63 Main Rotor Hub Assembly — (S/N 53000 through 53066Post TB 407-99-16 and S/N 53067 through 53631)— Installation ............................................................................ 62-00-00 120

62-64 Main Rotor Hub Assembly — (S/N 53000 through 53631Post TB 407-05-66 and S/N 53632 and Subsequent)— Installation ............................................................................ 62-00-00 132

62-65 Main Rotor System — Up and Down Stop Assemblies ................. 62-00-00 14162-66 Up and Down Stop Assemblies — Removal ............................ 62-00-00 14362-67 Up and Down Stop Assemblies — Inspection and Repair........ 62-00-00 14362-68 Up and Down Stop Assemblies — Installation ......................... 62-00-00 144

FIGURES

Figure Page Number Title Number

62-1 Main Rotor System ............................................................................................. 662-2 Main Rotor Hub Assembly — Inspection ............................................................ 762-3 Main Rotor Blade Assembly — Inspection.......................................................... 1362-3A Expandable Blade Bolts — 600-Hour or 12-Month Inspection ........................... 14A62-3B Blade Bolt — Wear, Damage, and Repair Limits................................................ 14C62-3C Expandable Blade Bolt — Wear, Damage, and Repair Limits............................ 14D62-4 Main Rotor Blade Bolts — Inspection ................................................................. 1562-5 Frahm Damper Assembly — Inspection ............................................................. 1662-6 Main Rotor Blade — Description......................................................................... 2262-7 Main Rotor Blade Bolts — Removal and Installation .......................................... 2462-8 Main Rotor Blade Assembly................................................................................ 2762-9 Main Rotor Blade Closure — Repair................................................................... 2862-10 Main Rotor Blade Trim Tab Assembly — Replacement ..................................... 3462-11 Main Rotor Blade Cross-Sectional View ............................................................. 3762-12 Main Rotor Blade Skin — Repair ........................................................................ 4062-13 Main Rotor Blade Core — Repair ....................................................................... 4462-14 Main Rotor Blade Trailing Edge — Repair.......................................................... 4862-15 Main Rotor Blade Tip Components..................................................................... 5062-16 Polyurethane Protective Tape — Installation...................................................... 5762-17 Frahm Assembly — Removal and Installation .................................................... 6062-18 Frahm Assembly and Workaids .......................................................................... 6162-19 Frahm Assembly Springs — Removal and Installation....................................... 6462-20 Frahm Stop Assembly......................................................................................... 6662-21 Upper Plate — Wear, Damage, and Repair Limits ............................................. 6862-22 Pad Assembly — Wear, Damage, and Repair Limits ......................................... 7062-23 Spring — Wear, Damage, and Repair Limits...................................................... 7162-24 Plug — Wear, Damage, and Repair Limits ......................................................... 7262-25 Weight Assembly — Wear, Damage, and Repair Limits .................................... 7362-26 Seat — Wear, Damage, and Repair Limits......................................................... 75

BHT-407-MM-6

62-00-00Page 4 Rev. 35 10 DEC 2012 Export Classification C, ECCN EAR99

FIGURES (CONT)

Figure Page Number Title Number

62-27 Housing — Wear, Damage, and Repair Limits ................................................... 7662-28 Retaining Plate — Wear, Damage, and Repair Limits........................................ 7862-29 Stop Assembly Retaining Plate — Wear, Damage, and Repair Limits............... 8062-30 Stop Assembly Adapter — Wear, Damage, and Repair Limits........................... 8162-31 Mast Nut (S/N 53000 through 53631 Pre TB 407-05-66) — Removal

and Installation.................................................................................................... 9362-32 Mast Nut (S/N 53000 through 53631 Post TB 407-05-66 and S/N 53632

and Subsequent) — Removal and Installation.................................................... 9462-33 Main Rotor Hub Assembly .................................................................................. 9662-34 Mast Nut — Wear, Damage, and Repair Limits.................................................. 10462-34A Mast Nut — Finishing.......................................................................................... 10662-35 Mast Nut Lock (407-010-109) — Wear, Damage, and Repair Limits ................. 106B62-36 Mast Nut Lock (407-010-117) — Wear, Damage, and Repair Limits ................. 10762-37 Retainer — Wear, Damage, and Repair Limits................................................... 10962-38 Upper Cone — Wear, Damage, and Repair Limits............................................. 11162-39 Center Cone Set — Wear, Damage, and Repair Limits ..................................... 11262-40 Lower Cone — Wear, Damage, and Repair Limits............................................. 11362-41 Main Rotor Hub Center Cone Set, Lower Seat, and Lower Cone

(S/N 53000 through 53066 Pre TB 407-99-16)................................................... 11662-42 Main Rotor Hub Center Cone Set, Lower Seat, and Lower Cone (S/N 53000

through 53066 Post TB 407-99-16 and S/N 53067 through 53631) ................... 12262-43 Integral Mast Center Cone and Main Rotor Hub Lower Seat and Lower Cone

(S/N 53000 through 53631 Post TB 407-05-66 and S/N 53632 and Subsequent) 13462-44 Main Rotor Hub Assembly — Alignment Workaid .............................................. 13862-45 Hub Sling and Support Tool................................................................................ 13962-46 Up and Down Stop Assemblies — Removal and Installation ............................. 142

TABLES

Table Page Number Title Number

62-1 Frahm Production Effectivity .............................................................................. 8362-2 Frahm Assembly Configurations......................................................................... 84

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 5

MAIN ROTOR SYSTEM

62-1. MAIN ROTOR SYSTEM —DESCRIPTION

The main rotor system is the primary lift, thrust, andcontrol device for the helicopter. The main rotorsystem is made up of the cover (1, Figure 62-1), theFrahm assembly (2), the main rotor hub assembly (3),and the four composite main rotor blades (8).

NOTE

For flight operations with the Frahmdamper and cover removed, refer to TB407-03-51.

The cover (1) is constructed of fibe rglass and isaerodynamically shaped for drag and noise reduction.The cover is installed on to p of the F rahm assembly(2) to p rotect the Frahm assembly mechanism fromthe environment. You must remove the cover beforeyou can remove the Frahm assembly.

The Frahm assembly (2) is a vi bration absorbingmechanism that is made up of springs and weightsthat reduce the main rotor 4/rev vibrations that aretransferred into the ai rframe. You must remove theFrahm assembly before you can remove the m ainrotor hub assembly (3).

The main rotor blades (8) are the airfoils that supplythe force for li ft and directional flight. Each main rotorblade is connected to the main rotor blade grip (4) bytwo fixed diameter blade bolts (7). A blade fold kit is anoption. The blade fold kit replaces two fixed diameterblade bolts with two ex pandable blade bolts (9).Depending on the blade folding configuration, the fixeddiameter blade bolts that are in the leading edge of thegreen blade and in the trailing edge of the orangeblade, or the trailing edge positions of the red and blueblades, are replaced with the expandable blade bolts.The two optional installation positions for theexpandable blade bolts will allow for two blades to befolded in the same direction, or one blade forward andone blade aft. The expandable blade bolts are usedbecause they are easy to remove when you fold themain rotor blades.

62-2. MAIN ROTOR SYSTEM —OPERATIONAL CHECK

For the main rotor track and balance procedures,operational checks, and troubleshooting procedures,refer to Chapter 18.

62-3. MAIN ROTOR SYSTEM — GENERALCONDITION AND SECURITY —INSPECTION

1. Inspect main rotor hub assembly (3, Figure 62-1)for general condition and security as follows:

a. Examine sealant (C-308) applied at thefollowing locations for condition. If sealant (C-308) isdamaged to an extent where water or moisture canpenetrate the joint, replace sealant (C-308):

• At the base of the mast nut (1, Figure 62-2) ifFrahm is removed

• Around the main rotor hub assembly throughbolt heads (23) if Frahm is removed

• At the j oint between the upper plate (6) andthe yoke (7)

• At the joint between the yoke (7) and the lowerplate (25)

• At the joint between the lower plate (25) andthe lower cone seat (26)

• At the joint between the lower cone seat (26)and the lower cone (15)

Refer to BHT-ALL-SPM for specifications.

MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-101 Corrosion Preventive Compound

C-308 Sealant

BHT-407-MM-6

62-00-00Page 6 Rev. 26 23 DEC 2009 ECCN EAR99

Figure 62-1. Main Rotor System407MM_62_0001_c01

1

2

5

34

12

7

8

6

10

9

11

1. Cover 2. Frahm assembly 3. Main rotor hub assembly 4. Main rotor blade grip 5. Red blade index 6. Main rotor blade up stop 7. Fixed diameter blade bolt 8. Main rotor blade 9. Expandable blade bolt (optional)10. Pitch horn11. Mast12. Yoke

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 7

Figure 62-2. Main Rotor Hub Assembly — Inspection (Sheet 1 of 5)407MM_62_0041_c01

7

SEE DETAIL A

RED INDEX PAINT

MASTER SPLINE

(RED BLADE)

65

8

4

3

1 2

30

24

23

21

22

20

161918

1217

SEE DETAIL D AND D1 2

9

13

14

15

12 10

11

4

5

BHT-407-MM-6

62-00-00Page 8 Rev. 23 7 NOV 2006

Figure 62-2. Main Rotor Hub Assembly — Inspection (Sheet 2 of 5)407MM_62_0042

SEE DETAIL C AND C1 2

DETAIL AS/N 53000 THROUGH 53066 POST TB 407-99-16 AND

S/N 53067 AND SUBSEQUENT SHOWN

25

SECTION B-B

25

26

27

28

28

296

15

30

31

1

23

6

7

26

1

B

B

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 9


2

1DETAIL CS/N 53000 THROUGH 53066 PRE TB 407-99-16

NO SEALANT

26

15

13

28

27

DETAIL CS/N 53000 THROUGH 53066 POST TB 407-99-16 AND

S/N 53067 AND SUBSEQUENT

NO SEALANT

26

15

13

28

29

28

27

3

2

1

BHT-407-MM-6

62-00-00Page 10 Rev. 23 7 NOV 2006


BUSHING FLANGE

16

11

12

10

19

18

17

12

1DETAIL DS/N 53000 THROUGH 53414 PRE TB 407-00-22

2DETAIL D S/N 53000 THROUGH 53414 POST TB 407-00-22 AND

S/N 53415 AND SUBSEQUENT

16

1112

10

19

18

17

12

BHT-407-MM-6

62-00-002 OCT 2007 Rev. 24 Page 11

Figure 62-2. Main Rotor Hub Assembly — Inspection (Sheet 5 of 5)407MM_62_0045_C02

NOTES

Safety in pairs.

Do not apply sealant to nut.

Lock and retainer applicable S/N 53000 through 53631 Post TB 407-05-66 and S/N 53632 and

subsequent.

On S/N 53000 through 53631 Post TB 407-05-66 and S/N 53632 and subsequent, the center

cone set has been replaced with an integral one piece cone on the mast.

CORROSION PREVENTIVE COMPOUND (C-101)

LOCKWIRE (C-405) OR SAFETY CABLE (C-152) AND FERRULE (C-153)

SEALANT (C-308)

1

2

3

4

5

1. Mast nut 2. Upper cone 3. Bolt 4. Washer 5. Lock or lock and retainer 6. Upper plate 7. Yoke 8. Elastomeric lead-lag damper 9. Elastomeric pivot (feathering) bearing10. Bolt11. Floating bushing12. Washer13. Mast14. Center cone set15. Lower cone16. Pitch link

17. Pitch horn18. Nut19. Cotter pin20. Elastomeric shear bearing21. Main rotor blade grips22. Buffer pads23. Through bolts24. Main rotor hub assembly25. Lower plate26. Lower cone seat27. Bolt28. Washer29. Nut30. Up stop31. Down stop

1

Apply a coating of corrosion preventive compound (C-101) to all bolt heads, washers, nuts and

exposed threads after installation.

BHT-407-MM-6


• At the joint between the lower cone (15) andthe mast (13); ensure the lower cone splitremains open

b. Examine the upper plate (6) and lower plate(25) for damage.

NOTE

Splinters in the yoke occur when fibers inthe surface plies have broken loose orseparated from the lower plies. You canusually find splinters at the machined ormolded edges of the laminates. Edgedelamination in the yoke occurs when theplies separate from each other.

c. Examine the yoke (7) for void and edgedelamination.

d. Examine the y oke (7) radius for contact withthe elastomeric pivot bearing (9) bolt heads.

e. Examine the main rotor blade grips (21) fordamage.

f. Examine all bolts and nuts for safety andmissing corrosion preventive compound (C-101).

NOTE

The latest configuration pitch horn has atungsten carbide coated surface in lieu ofthe bonded stainless steel buffer pad.

g. Examine the pitch horns (17) for damage. Ifapplicable, examine the s tainless steel buffer pads(22) for debonding or voids.

h. Examine the attachment of the pitch links (16)to the pitch horns (17). Ensure the nuts (18) are tightand safetied with cotter pins (19). Examine hardwarefor missing corrosion preventive compound (C-101).

NOTE

Misalignment of the radial injection lines onthe elastomeric shear bearings (20)outboard surface is not cause for rejection.Refer to the BHT-407-CR&O, Chapter 62Inspection section for more details.

i. Examine the elastomeric shear bearings (20)and elastomeric pivot bearings (9) for the followingdamage:

• Missing elastomeric material

• Elastomeric material ejected out between theshims

• Corrosion on metal parts of the bearing

• Cracks in metal parts of the bearing

j. Examine the elastomeric lead-lag damperbearings (8) for the following damage:

• Corrosion on the metal part of the elastomericlead-lag damper (8)

• Tears, cracks, or debonded areas in th eelastomer

• Evidence of contact of rubber bumper withinside surfaces of yoke

k. Examine the up and down stops (30 and 31)for cracks, wear, or deformation of plug, and performthe following:

(1) Ensure the plug is in the safety and thecotter pins lock the plug.

NOTE

The latest configuration stud has no holedrilled in the base of the cup.

(2) Examine the stud for damage. Payparticular attention in the radius at the base of the cupfor cracks. Look also for cracks that may develop fromhole to hole.

(3) Ensure the stud is covered with corrosionpreventive compound (C-101).

2. Inspect main rotor blades (Figure 62-3) forgeneral condition and security, as follows:

a. Examine for cleanliness.

b. Examine the leading edge erosion strip (9) forwear, deformation, holes, cracks, tears, scratches, andedge voids.

c. Examine the blade upper and lower skins (11and 12) for scratches, nicks, gouges, dents, ordelamination.

d. Examine the extreme trailing edge strip (13)for nicks, notches, and voids at the bonding line.

e. Examine the trim tab assembly (29) for nicks,scratches, voids, or corrosion.

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 13

Figure 62-3. Main Rotor Blade Assembly — Inspection407MM-62-0046

4

1. Spacer assembly

2. Liner

3. Bushing

4. Fretting pad

5. Butt closure

6. ID tag

7. Nameplate

8. Forward closure

9. Erosion strip

10. Spar assembly

11. Upper skin

12. Lower skin

13. Trailing edge strip

14. Decal

15. Aft root closure

16. Plate

17. Screw

18. Shim

19. Screw

21. Weight

22. Retainer

23. Insert threaded

24. Screw

20. Cover -

product balance

25. Tiedown plate

26. Cover -

product balance

27. Erosion shield

28. Screw

29. Trim tab assembly

30. Core

SEE DETAIL A

2

3

5 7

4

16

149

15 30

17

19

20

21

22

28

1311

21

18

26

24

1

25

18

29

13

12

27

23

8

9

10

6

7

DETAIL A

BHT-407-MM-6


f. Examine the product balance weight pocketcovers (20 and 26) for loose or missing screws (17,19, and 28). Examine the aerodynamic filler applied onand around the covers for condition.

g. Examine the tie down plate (25) for damageand looseness.

h. Examine the blade root closures (8 and 15) fordebonding or cracks.

i. Examine the paint for general condition.

j. Examine the blade for any evidence ofdamage caused by an incident or accident.

3. Examine the fixed diameter blade bolts (2,Figure 62-4) for mechanical damage, corrosiondamage, and missing corrosion preventive compound(C-101) (Figure 62-3B). Ensure the nut (8) is safetiedwith the cotter pin (9).

4. If the optional expandable blade bolts (12) areused, examine them for mechanical damage andcorrosion damage (Figure 62-3C). Ensure the safetylock hair pin (15) is correctly attached to theexpandable blade bolt and bolt handle (13).

5. Examine the Frahm damper cover (1,Figure 62-5) for loose screws (8), cracks, anddelamination.

6. Examine the Frahm damper assembly (2) asfollows:

a. Examine the Frahm housing (3) and Frahmupper plate (4) for damage and cracks. Pay particularattention to the Frahm attaching lugs (5).

b. Examine the nut and the washer (6 and 7) forcondition, looseness, and missing corrosionpreventive compound (C-101).

62-3A. EXPANDABLE BLADE BOLTS —600-HOUR OR 12-MONTHINSPECTION

CAUTION

DO NOT CLOSE THE HANDLE OF THEEXPANDABLE BLADE BOLT WHEN NOTINSTALLED OR DAMAGE TO THE BOLTSEGMENTS MAY OCCUR.

1. Make sure the bolt handle (2, Figure 62-3A) isopen and the nut (4) points up.

2. Remove the nut (4) from the core pin (5).

SPECIAL TOOLS REQUIRED

NUMBER NOMENCLATURE

— Blade Bolt Segments Removal/Installation Workaid

NOTE:

Refer to Figure 62-3A.


MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-021 Solid Film Lubricant

C-305 Aliphatic Naphtha

C-385 Isopropyl Alcohol

C-423 Abrasive Paper

C-516 Clean Cloth

C-561 Grease

NOTE:

Use 240, 320, and 400 grit.

1

1

1

1

BHT-407-MM-6

62-00-00ECCN EAR99

Figure 62-3A. Expandable Blade Bolts — 600-Hour or 12-Month Inspection (Sheet 1 of 2)

3

5

4

3

2

1

5

407_MM_62_0093a

BLADE BOLT SEGMENTSREMOVAL/INSTALLATION

WORKAID


WORKAID

BLADE BOLT SEGMENTSREMOVAL/INSTALLATION WORKAID APPLICATION

16 FEB 2012 Rev. 34 Page 14A

BHT-407-MM-6

ECCN EAR9962-00-00

Figure 62-3A. Expandable Blade Bolts — 600-Hour or 12-Month Inspection (Sheet 2 of 2)

A

B

VIEW A

2.0 IN.(50.8 mm)

0.625 IN.(15.87 mm)

DIA.

0.250 IN.(6.35 mm)

DIA.

0.375-24 UNJF-3B THREADPER MIL-S-88791 INCH (25.4 mm) MINFULL THREAD DEPTH

VIEW B

10 IN.(254.0 mm)


WORKAID

407_MM_62_0093b

Expandable blade boltBolt handleSegmentsNutCore pin

1.2.3.4.5.

GREASE (C-561)

Page 14B Rev. 34 16 FEB 2012

BHT-407-MM-6

62-00-00Export Classification C, ECCN EAR99

Figure 62-3B. Blade Bolt — Wear, Damage, and Repair Limits

NO OBJECT BEYOND THIS POINT 407CRO_62_0079_c02

1/3 of thread.D8.

C7.

MeasureMechanical/corrosionedge chamfer damage

B6.

Two.Number of repairsB, C

B

C, F

B

C

5.

METHODINSPECTION

LIMIT

Measure

Measure

Measure

0.002 inch (0.051 mm).

0.010 inch (0.254 mm).

CHARACTERISTICNO.

Mechanical/corrosiondamage

Maximum area perfull depth repair


1.

2.

3.

4.


LTRREF

BLADE BOLT (406-010-120-ALL)

Thread damage:

Length:Depth:

Number:0.250 inch (6.35 mm).One.

Measure

Measure

Mechanical/corrosionedge chamfer damage

CORK C

B

D

B

VIEW A

A

0.500 square inch (322.5859 mm²).

0.250 square inch (161.2959 mm²).

MATERIAL: STEEL ALLOY

E

E Visual None permitted.Mechanical/corrosiondamage

9.

0.030 inch (0.762 mm)for full chamfer surface.

0.010 inch (0.254 mm)for full chamfer surface.

F

(CORK NOT SHOWN FOR CLARITY)

10 DEC 2012 Rev. 35 Page 14C

BHT-407-MM-6

ECCN EAR9962-00-00

Figure 62-3C. Expandable Blade Bolt — Wear, Damage, and Repair Limits

Page 14D Rev. 34 16 FEB 2012

BHT-407-MM-6

62-00-00ECCN EAR99

3. Install the workaid on the threaded end of thecore pin (5). Hand-tighten the workaid.

4. While you hold the bolt handle (2) and thesegments (3) in position, carefully turn the expandableblade bolt (1) to allow the segments to slide on theworkaid.

5. While you keep the segments (3) on the workaid,clean them and the core pin (5) with a clean cloth(C-516) dampened with aliphatic naphtha (C-305) orisopropyl alcohol (C-385). Make sure to remove all dirtand debris.

6. Fully dry the segments (3) and the core pin (5)with filtered compressed air and a clean cloth (C-516).

7. Visually examine the bolt handle (2), segments(3), and core pin (5) for cracks, fretting, mechanicaldamage, corrosion damage, and missing or burnishedsolid film (Figure 62-3C).

8. As required, repair damage as follows:

a. Blend the damage smooth with 240 gritabrasive paper (C-423) followed by 320 and 400 gritabrasive paper (C-423). Do not exceed the damagelimits shown in Figure 62-3C.

b. Apply solid film lubricant (C-021) to areaswhere lubricant is missing or burnished. If lubricant onthe core pin (5, Figure 62-3A) is missing on more than50% of the surface, the core pin is not repairable.

9. Apply a thin layer of grease (C-561) on allsurfaces of the core pin (5) and the segments (3), asshown in Figure 62-3A.

10. While you hold the bolt handle (2) and thesegments (3) in position, carefully turn the expandableblade bolt (1) to allow the segments to slide on thecore pin (5).

11. Make sure all the segments (3) are correctlyseated against each other.

12. Remove the workaid from the core pin (5).

13. Install the nut (4) on the core pin (5). Tighten thenut.

14. Do a tension check of the expandable blade bolt(1) in accordance with the instructions in paragraph62-48).

62-4. MAIN ROTOR SYSTEM —UNSCHEDULED INSPECTIONS

Paragraph 62-5 through paragraph 62-10 provideinformation to conduct unscheduled inspections of themain rotor system. The following unscheduledinspections are provided for the main rotor:

• Hard landing

• Sudden stoppage

• Overtorque (110 to 120%)

• Overtorque (above 120%)

• Overspeed (in excess of 118% NR)

• Lightning strike

62-5. MAIN ROTOR — HARD LANDINGINSPECTION

1. Inspect main rotor blades as follows:

a. Examine the blades (Figure 62-3) for skinwrinkles, cracks, or deformation.

CAUTION

DAMAGE TO BLADE CAN BE CAUSEDBY IMPROPER USE OF TAP HAMMER.

b. Use a small tap hammer T75449-2 andexamine the blades for voids and delamination.

c. If a blade shows any of the above signs put atag on the blade and write “this blade was removedfrom service because of a hard landing”. Send the


NUMBER NOMENCLATURE

T75449-2 Tap Hammer

16 FEB 2012 Rev. 34 Page 14E

BHT-407-MM-6

ECCN EAR9962-00-00

blade to a BHT approved blade repair facility forevaluation. Blades having no damage should be testflown (tracked, balanced, and vibration monitored) todetermine their serviceability. If a blade does notdemonstrate serviceability after test flight, put a tag onit and write “This blade was removed because of ahard landing”. Send the blade to a BHT approvedrepair facility for evaluation.

d. Examine each blade’s lower surface outboardof the trim tab for damage caused by contact with thefinlets.

e. Examine each blade’s tip for damage causedby contact with the tail rotor driveshaft cover ordriveshaft.

Page 14F Rev. 34 16 FEB 2012

BHT-407-MM-6


Figure 62-4. Main Rotor Blade Bolts — Inspection407MM_62_0047_c01

ADETAIL

1. Main rotor grip2. Fixed diameter blade bolt3. Main rotor blade4. Sling (T101626)5. Tiedown plate6. Trim tab7. Washer8. Nut

14. Adjustment nut13. Bolt handle12. Expandable blade bolt (optional)

9. Cotter pin10. Color coded marks

OPTIONAL EXPANDABLE BOLT

STA 108.25APPROXIMATE CENTEROF GRAVITY (CG)OF THE BLADE

144.00

The trailing edge position of the orange blade and the leading edge position of the green blade.The expandable blade bolts (12) may only be installed in one of the following positions:

11. Drain hole

15. Safety lock hair pin

The trailing edge positions of the red blade and the blue blade.or

CORROSION PREVENTIVE COMPOUND (C-101)45 TO 65 FT-LBS(61.01 TO 88.13 Nm)

3

NOTES1

2

3

SEE DETAIL A13

12

1514

21

3

10

2

1

9

8

7

6

11 5

STA

Apply a coating of corrosion preventive compound (C-101) to all bolt heads, washers, nuts and exposed threads after installation.

For operators that require blade folding, use the expandable blade bolt (12) in lieu of fixed diameter blade bolt (2), washer (7), nut (8) and cotter pin (9).

BHT-407-MM-6


Figure 62-5. Frahm Damper Assembly — Inspection407MM_62_0048_c02

1

2

6

79

53

6

7

8


50 TO 70 IN-LBS(5.6 TO 7.9 Nm)

75 TO 95 IN-LBS(8.5 TO 10.7 Nm)

2

For detailed breakdown of Frahm damper, refer to Figure 62-18.

Apply a coating of corrosion preventive compound (C-101) to all bolt heads, washers, nuts, and exposed

threads after installation.

2

NOTES

1.

4

2

2

1. Damper cover2. Frahm damper assembly3. Frahm housing4. Frahm upper plate5. Frahm attaching lugs6. Nut7. Washer8. Screw9. Main rotor hub assembly

1

1

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 17

2. If installed, inspect Frahm damper cover andFrahm damper assembly (Figure 62-5) as follows:

a. Examine Frahm damper cover for cracks,deformation, or delamination. Pay particular attentionin the attachment hole areas.

b. Remove Frahm damper upper plate andinspect for cracks and any other type of damage.

c. Inspect Frahm damper housing for cracks orany other type of damage. Pay particular attention inthe attachment lug areas.

d. Examine weight assembly (Figure 62-18) andhousing for evidence of contact.

e. Examine springs for cracks.

f. If damage is found, contact Product SupportEngineering.

3. Inspect main rotor hub assembly (Figure 62-2) asfollows:

a. Examine the upper and lower plate up an ddown stop attachment points for deformation orcracks.

b. Examine up an d down stop plugs and studsfor deformation or cracks.

CAUTION

DAMAGE TO YOKE CAN BE CAUSED BYIMPROPER USE OF TAP HAMMER.

c. Use a s mall tap hammer T75449-2 andexamine the yoke for delamination.

d. Examine yoke flexures inside surfaces forevidence of contact with lead and lag dampers of pivotbearing attachment bolts.

e. Examine yoke for cracks.

f. Examine lower cone seat for cracks.

g. Examine pitch horn for deformation anddebonding of buffer pads.

h. Remove main rotor blades (paragraph 62-12)and examine main rotor blade grips for deformationand grip spacing.

i. Examine all elastomeric bearings for damage.

j. If the main rotor hub assembly shows any ofthe above signs or other signs of damage that arepossibly related to the hard landing, put a tag on hubassembly and write “this main rotor hub assembly wasremoved from service because of a har d landing”.Send the main rotor hub assembly to an approvedfacility for overhaul. If you do not find any damage, themain rotor hub assembly is serviceable.

62-6. MAIN ROTOR — SUDDEN STOPPAGEINSPECTION

1. Inspect main rotor b lades (Figure 62-3) asfollows:

a. Examine the b lades for evidence of damage.Look for dents, cracks, wrinkles, and deformation.

CAUTION


b. Use a s mall tap hammer T75449-2 andexamine the blades for voids and delamination.

c. If a blade shows any of the above signs, put atag on the blade and write “this blade was removedfrom service because of a s udden stoppage”. Sendthe blade to a BHT approved blade repair facility forevaluation. Blades having no damage should be testflown (tracked, balanced, and vibration monitored) todetermine their serviceability. If a blade does notdemonstrate serviceability after test flight, put a tag onblade and write “this blade was removed because of asudden stoppage”. Send the blade to a BHT approvedblade repair facility for evaluation.


NUMBER NOMENCLATURE

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62-00-00Page 18 Rev. 23 7 NOV 2006

d. Look for evidence of pr oduct balance weightmovement. Look for loose screws or a lo ose cover,cracks, deformation, or a void in the product balanceweight pocket areas. If product balance weights havemoved, discard the blade. If in doubt, contact ProductSupport Engineering.

e. If a blade is damaged beyond repair anddiscarded, put a t ag on eac h remaining blade andwrite, “this blade was removed from service becauseof sudden stoppage”. Send the remaining blades to aBHT approved blade repair facility for evaluation.

f. If the blades are intact or show minorrepairable damage, they should be test flown (tracked,balanced, and vibration monitored) to determine theirserviceability. If the blade does not de monstrateserviceability after test flight, put a t ag on blade andwrite “this blade was removed from service because ofa sudden stoppage”. Send the blade to a BHTapproved blade repair facility for evaluation.

g. If the mast was severed as a r esult of asudden stoppage, discard all four main rotor blades.

2. If installed, inspect Frahm damper cover andFrahm damper assembly (Figure 62-5) as follows:

a. Examine Frahm damper cover for cracks,deformation, or delamination. Pay particular attentionin the attachment hole areas.

b. Remove Frahm damper upper plate andinspect for cracks and any other type of damage.

c. Inspect Frahm damper housing for cracks orany other type of damage. Pay particular attention inthe attachment lug areas.

d. Examine weight assembly (Figure 62-18) andhousing for evidence of contact.

e. Examine springs for cracks.

f. If damage is found, contact Product SupportEngineering.

3. Inspect main rotor hub assembly (Figure 62-2) asfollows:


b. Examine up a nd down stop plugs and studsfor deformation or cracks.

CAUTION



d. Examine yoke flexures inside surfaces forevidence of contact with lead and lag dampers of pivotbearing attachment bolts.

e. Examine yoke for cracks.

f. Examine lower cone seat for cracks.

g. Examine pitch horn for deformation.

h. Remove main rotor blades (paragraph 62-12)and examine main rotor blade grips for deformationand grip spacing.

i. Examine all elastomeric bearings for damage.

j. If the main rotor hub assembly shows any ofthe above signs or other signs of damage that arepossibly related to the sudden stoppage, put a tag onhub assembly and write “this main rotor hub assemblywas removed from service because of a suddenstoppage”. Send the main rotor hub assembly to anapproved facility for overhaul. If you do not f ind anydamage, the main rotor hub assembly is serviceable.

k. If a main rotor blade is damaged beyondrepair and discarded or requires to be sent to a BHTapproved blade repair facility, remove the main rotorhub assembly. Put a tag on hub assembly and write“this main rotor hub assembly was removed fromservice because of a sudden stoppage”. Send themain rotor hub assembly to a BHT approved facility foroverhaul.

l. If the main rotor mast was severed as a resultof sudden stoppage, discard the main rotor hubassembly.

m. If the main rotor hub assembly is notdamaged, it is serviceable.

BHT-407-MM-6

62-00-002 OCT 2007 Rev. 24 Page 19

62-7. MAIN ROTOR — OVERTORQUEINSPECTION — AFTER OVERTORQUE 110TO 120%

1. Inspect main rotor blades (Figure 62-3), asfollows:

a. Examine the blades for evidence of damage.Look for cracks, wrinkles, deformation, anddebonding.

CAUTION



c. If a blade shows any of the above signs, put atag on the blade and write “this blade was removedfrom service because of an overtorque”. Send theblade to a BHT approved blade repair facility forevaluation. Blades having no damages should be testflown (tracked, balanced, and vibration monitored) todetermine their serviceability. If a blade does notdemonstrate serviceability after test flight, put a tag onblade and w rite “this blade was removed because ofan overtorque”. Send the blade to a BHT approvedblade repair facility for evaluation.

2. Inspect main rotor hub assembly (Figure 62-2),as follows:


b. Examine blade bolts for deformation andout-of-round (BHT-407-CR&O).

CAUTION



d. Examine yoke for cracks.

NOTE

Misalignment of the radial injection lines onthe shear bearings outboard surface is notcause for rejection. Refer to InformationLetter 407-07-93 for more details.

e. Examine shear bearings and pivot bearingsfor damage. Look for separated or crumbledelastomeric.

f. Examine elastomeric lead-lag dampers forseparated elastomeric.

g. If the main rotor hub assembly shows any ofthe above signs or other signs of damage that arepossibly related to ov ertorque, put a tag on hu bassembly and write “this main rotor hub assembly wasremoved from service because of an overtorque”.Send the main rotor hub assembly to an approvedfacility for overhaul. If you do not find any damage, themain rotor hub assembly is serviceable.

62-8. MAIN ROTOR — OVERTORQUEINSPECTION — OVERTORQUE ABOVE120%


a. Examine the b lades for evidence of damage.Look for cracks, wrinkles, deformation, anddebonding.


NUMBER NOMENCLATURE

T75449-2 Tap Hammer


NUMBER NOMENCLATURE

T75449-2 Tap Hammer

BHT-407-MM-6

62-00-00Page 20 Rev. 24 2 OCT 2007

CAUTION



c. If a blade shows any of the above signs, put atag on the blade and write “this blade was removedfrom service because of an overtorque”. Send theblade to a BHT approved blade repair facility forevaluation. Blades having no damages should be testflown (tracked, balanced, and vibration monitored) todetermine their serviceability. If a blade does notdemonstrate serviceability after test flight, put a tag onit and write “this blade was removed because of a novertorque above 120%”. Send the bla de to a BHTapproved blade repair facility for evaluation.

2. Remove the main rotor hub assembly (paragraph62-59), put a tag on hub assembly, and write “thismain rotor hub assembly was removed from servicebecause of an overtorque above 120%”. Send themain rotor hub assembly to an approved facility foroverhaul.

62-9. MAIN ROTOR — OVERSPEEDINSPECTION — AFTER OVERSPEED INEXCESS OF 118% NR


a. Examine the blades for skin wrinkles, cracks,or deformation.

CAUTION



c. If a blade shows any of the above signs, put atag on the blade and write “this blade was removedfrom service because of overspeed”. Send the bladeto a BHT approved blade repair facility for evaluation.

d. Examine blade bolt bushings for looseness(Figure 62-3). If the bushings are loose, discard theblade.

e. Blades showing no sign of damage should betest flown (tracked, balanced, and vibration monitored)to determine their serviceability. If a bl ade does notdemonstrate serviceability after test flight, put a tag onit and write “this blade was removed from servicebecause of overspeed”. Send the blade to a BHTapproved blade repair facility.

2. Inspect main rotor hub assembly, as follows:

a. Remove main rotor blades (paragraph 62-12)and examine main rotor blade grips (Figure 62-2) fordeformation and grip spacing (BHT-407-CR&O).

b. Examine blade bolts for yielding(BHT-407-CR&O). Yielded blade bolts must bediscarded.

CAUTION


c. Use a s mall tap hammer T75449-2 andexamine the yoke for delamination. If the yoke isdelaminated it must be discarded.

NOTE

Misalignment of the radial injection lines onthe shear bearings outboard surface is notcause for rejection. Refer to InformationLetter 407-07-93 for more details.

d. Examine shear bearings and pivot bearingsfor damage. Look for separated or crumbledelastomeric.


NUMBER NOMENCLATURE

T75449-2 Tap Hammer

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 21

e. Examine elastomeric lead-lag dampers forseparated elastomeric.

f. If the main rotor hub assembly shows any ofthe above signs or other signs of damage that arepossibly related to the overspeed, put a tag on hu bassembly and write “this main rotor hub assembly wasremoved from service because of an ov erspeed”.Send the main rotor hub assembly to an approvedfacility for overhaul. If you do not find any damage, themain rotor hub assembly is serviceable.

62-10. MAIN ROTOR — LIGHTNING STRIKEINSPECTION

1. Remove main rotor blades (paragraph 62-12).

2. Inspect main rotor bl ades (Figure 62-3) asfollows:

a. Examine main rotor blades for signs of burnsand arcing. Pay particular attention at the productbalance pocket covers (20 and 26), blade boltbushings (3), and liner (2).

CAUTION



c. If a blade shows any of the above signs, put atag on blade and write “this blade was removed fromservice because of a lightning strike”. Send the bladeto a BHT approved blade repair facility for evaluation.

d. If you do not see any burn marks or signs ofarcing, the blade is serviceable.

3. Inspect main rotor hub assembly as follows:

a. Examine the main rotor hub assembly(Figure 62-2) for burn marks and evidence of ar cing.Parts having burn marks or having evidence of arcingmust be discarded.

CAUTION


b. Use a s mall tap hammer T75449-2 andexamine the yoke for voids or delamination. If the yokeshows any sign of voids or delamination, it must bediscarded.

c. If the main rotor hub assembly shows any ofthe above signs or shows damage related to alightning strike, put a tag on it and mark “this mainrotor hub assembly was removed from servicebecause of a lightning strike”. Send the main rotor hubassembly to a BHT approved facility for analysis.

d. If you do not find any damage, the main rotorhub assembly is serviceable.

62-11. MAIN ROTOR SYSTEM — MAINROTOR BLADE DESCRIPTION

The main rotor blades (Figure 62-6) are constructed offour principal members. A fiberglass spar, fiberglassskins, fiberglass trailing edge strip, and a No mexhoneycomb core.

A corrosion resistant steel strip, that has an el ectronickel plating applied from station 138.00 to th e tip,covers the spar to provide protection against erosionand abrasion.

The main rotor blades are dynamically balanced andare interchangeable. There is an adj ustable titaniumtrim tab (5) installed on the trailing edge of each mainrotor blade at station 144.00. The trim tab is used toadjust the main rotor blade during tracking(Chapter 18).

The blade finish consists of a copper conductivecoating that protects the blade against lightning strikesand static charges. Polyamide epoxy primer and apolyurethane enamel coating complete the finish. Theblade total weight is approximately 58 pounds(28.3 kg).


NUMBER NOMENCLATURE

T75449-2 Tap Hammer

BHT-407-MM-6

62-00-00Page 22 Rev. 23 7 NOV 2006

Figure 62-6. Main Rotor Blade — Description407MM_62_0003

1. Blade bolt bushings

3. Bonded assembly

4. Leading edge erosion strip

5. Trim tab

6. Fretting pad

7. Leading edge erosion shield

8. Upper skin

9. Trailing edge

10. Lower skin

11. Core

12. Spar

48

1211

10

9

A

A

1

6

3

4

4

5 SEE DETAIL A

MAIN ROTOR BLADE

(407-015-001-ALL)

13

13. Root closure

16. Plates

2

2

16

15

2. Blade bolt bushing liner

15. Tiedown plate

14. Product balance weight pockets

14

DETAIL A

SECTION A-A

7

STA

210.00

STA

144.00

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 23

Each main rotor blade (3, Figure 62-7) is color codedaccording to position. The red blade is in the positionnext to the master spline on the mast. An index hole inthe main rotor hub assembly also identifies theposition of the red blade. The main rotor blades (3) areinstalled in the direction of rotation, starting at red,orange, blue, and then green. The main rotor bladegrip (1) and the rotating control components all havethe applicable color coded markings (Chapter 11).

62-12. MAIN ROTOR BLADE — REMOVAL

NOTE

Only the r emoval procedure for one mainrotor blade is given. The removal procedurefor the other three main rotor blades is thesame.

Lift the main rotor blade by hand only whena hoist is not available and only if you havetwo maintenance platforms.

1. Put the maintenance platform near thetransmission of the helicopter.

2. Put a blade rack near the work area.

3. Examine the main rotor blade (3, Figure 62-7)and main rotor blade grip (1) for color code marks. Ifthe color code marks are not visible, apply new colorcode marks before you remove the main rotor blade(3) (Chapter 11).

CAUTION

THE HOIST MUST BE RATED FOR AMINIMUM CAPACITY OF 1000 POUNDS(454 KG). IF YOU USE A HOIST THAT ISNOT RATED FOR THIS CAPACITY,DAMAGE TO THE HELICOPTER CANOCCUR.

ENSURE THAT THE HOIST IS OVER THECENTER OF GRAVITY OF THE MAINROTOR BLADE. THE CENTER OFGRAVITY FOR THE BELL MODEL 407MAIN ROTOR BLADE IS SHOWN ONFIGURE 62-2.

4. Attach the sling T101626 (4, Figure 62-7) to thehoist. Put the hoist directly over the center of gravity ofthe main rotor blade (3). Attach the sling (4) strapsaround the main rotor blade (3).

5. Attach a rope to the tiedown plate (5) at the endof the main rotor blade (3). Use the rope to control themain rotor blade (3) during the removal.

NOTE

The use of expand able blade bolts (12)instead of fixed diameter blade bolts (2) isoptional. The expandable blade bolts maybe installed on the trailing edge of theorange blade and the leading edge of th egreen blade, or on the tr ailing edgepositions of the red and blue blades.

CAUTION

THE MAIN ROTOR BLADES AND THEMAIN ROTOR HUB ASSEMBLYCOMPONENTS ARE COLOR CODEDFOR POSITION. ALL THE COMPONENTSOF ONE COLOR THAT ARE REMOVEDMUST BE INSTALLED IN THE SAMECOLOR LOCATION.

NOTE

Lift the main rotor blade (3) until the bladeis horizontal or slightly above horizontal torelease pressure on t he fixed diameterblade bolts (2) or the optional expandableblade bolt (12).

6. If the helicopter has the blade fold kit, remove thesafety lock hair pin (15) from the lo wer end of theexpandable blade bolt (12). Pull the bolt handle (13)out and up to r educe the diameter of the expandableblade bolt. Remove the expandable blade bolt.


NUMBER NOMENCLATURE

T101626 Sling

BHT-407-MM-6


Figure 62-7. Main Rotor Blade Bolts — Removal and Installation

NO OBJECT BEYOND THIS POINT 407MM_62_0002_c01

ADETAIL

1. Main rotor blade grip2. Fixed diameter blade bolt3. Main rotor blade4. Sling (T101626)5. Tiedown plate

6. Trim tab7. Washer8. Nut

14. Adjustment nut13. Bolt handle12. Expandable blade bolt (optional)

9. Cotter pin10. Color coded marks

OPTIONAL EXPANDABLE BOLT

STA 108.25APPROXIMATECENTER OF GRAVITY (CG)OF THE BLADE

144.00

The trailing edge position of the orange blade and the leading edge position of the green blade.The expandable blade bolts (12) may only be installed in one of the following positions:

11. Drain hole

15. Safety lock hair pin

The trailing edge positions of the red blade and the blue blade.or

CORROSION PREVENTIVE COMPOUND (C-104) OR GREASE (C-561)

45 TO 65 FT-LBS(61.01 TO 88.13 Nm)

3

NOTES

13

12

1514

21

3

10

2

1

SEE DETAIL A

9

8

7

6

11 5

STA


4

4

Apply a coating of corrosion preventive compound (C-101) to all bolt heads, washers, nuts and exposedthreads after installation.

Apply a coating of corrosion preventive compound (C-104) or grease (C-561) to all bolt shanks prior toinstallation. Do not apply corrosion preventive compound (C-104) or grease (C-561) to bolt threads.

For operators that require blade folding, use the expandable blade bolt (12) in lieu of fixed diameter bladebolt (2), washer (7), nut (8) and cotter pin (9).

1

2

1

1

1

2

1

2

3

4

BHT-407-MM-6

62-00-0011 JUL 2011 Rev. 31 Page 25ECCN EAR99

7. Remove the cotter pin (9), nut (8), washer (7),and the fixed diameter blade bolt(s) (2) from the mainrotor blade grip (1).

8. Remove the main rotor blade (3) from the mainrotor blade grip (1). Use the rope attached to thetiedown plate (5) to control the main rotor blade (3) asyou lower it to the blade rack.

9. Remove the rope from the tiedown plate (5), thesling (4), and the hoist from the main rotor blade (3).

62-13. MAIN ROTOR BLADE — CLEANING

1. Wipe the main rotor blades (3, Figure 62-7) with acloth dampened with aliphatic naphtha (C-305) ordrycleaning solvent (C-304).

2. Clean main rotor blades (3) with a mild solution ofcleaning compound (C-318) and water. Rinse mainrotor blades (3) with clean water and dry with a cleancloth.

CAUTION

DO NOT USE SILICONE TYPE WAXES.S IL ICONE WAXES CAN CAUSEPROBLEMS WITH FUTURE REPAIRS.

3. Apply a layer of wax (C-412) to the main rotorblades (3).

62-14. MAIN ROTOR BLADE — NORMAL/CONDITIONAL INSPECTIONS

WARNING

EXCEPT AS NOTED IN PARAGRAPH62-20, IF YOU FIND CRACKS IN THEBONDED ASSEMBLY AREA OF THEMAIN ROTOR BLADE, THE BLADE ISUNSERVICEABLE. YOU MUST REMOVETHE UNSERVICEABLE BLADE ANDINSTALL A SERVICEABLE BLADE.

CAUTION

THE INSPECTION CRITERIA DEFININGACCEPTABLE DEFECTS IN THISMANUAL ARE INTENDED TO BE USEDAS A GENERAL GUIDE. IT IS VIRTUALLYIMPOSSIBLE TO DESCRIBE ALLDEFECTS THAT COULD OCCUR ON THEROTOR BLADE. EXCEPT IN CASESWHERE BLADES FALL INTO OBVIOUSSCRAP CATEGORY, PRODUCTSUPPORT ENGINEERING SHOULD BECONSULTED PRIOR TO SCRAPPINGBLADE. IN SOME CASES, L IMITSSPECIFIED CAN BE EXCEEDED INCERTAIN AREAS AND POSSIBLEREPAIRS CAN BE DEVISED BY MUTUALAGREEMENT OF BELL HELICOPTERAND USER.

NOTE

A void is defined as an unbonded area thatis supposed to be bonded. Manysubdefinitions of voids are frequently used,such as lack of adhesive, gas pocket,misfit, etc. This manual makes nodistinction between these definitions. All ofthese definitions are grouped into onegeneral term: void.

Voids may be detected by mechanicaltapping. Tap the surface of the main rotorblades with a small tap hammer, T75449-2,to find the voids. Approximately 200taps-per-minute will produce a constant


MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-304 Drycleaning Solvent


C-318 Cleaning Compound

C-412 Wax

BHT-407-MM-6

62-00-00Page 26 Rev. 30 8 APR 2011 ECCN EAR99

sound level that will change the tone overvoided areas.

1. To carry out a normal inspection of a main rotorblade, complete the steps in paragraph 62-15 throughparagraph 62-25.

2. If records or physical appearance of main rotorblade indicate that the blade has been subject to anaccident, incident, or usage outside the extent ofnormal usage, complete normal inspections of mainrotor blade as per paragraph 62-15 through paragraph62-25 and conditional inspections as per paragraph62-26 through paragraph 62-29.

62-15. MAIN ROTOR BLADE — RETENTION BOLTHOLES BUSHING LINER — INSPECTION

1. Inspect the bushing liners (2, Figure 62-8) forpitting, corrosion, and mechanical damage.

a. If pitting, corrosion, or mechanical damage arefound, polish out with 400 grit abrasive paper (C-423).

b. Using a micrometer, measure the insidediameter of the repaired liners. An inside diameter ofmore than 1.002 inches (25.45 mm) requiresreplacement of the liner.

c. If the liner needs replacing, send the mainrotor blade to a BHT approved blade repair facility.

62-16. MAIN ROTOR BLADE — FRETTING PADS— INSPECTION

1. Inspect the fretting pads (4, Figure 62-8) forcracks, voids, and security.

a. Edge voids less than 0.125 inch (3.175 mm)may be repaired by sealing with adhesive (C-363).

b. Edge void deeper than 0.125 inches (3.175mm) requires replacement of fretting pad.

2. If the fretting pad needs replacement, send themain rotor blade to a BHT approved blade repairfacility.

62-17. MAIN ROTOR BLADE — ROOT ENDCLOSURE — INSPECTION

1. Inspect the root end closures (5, 8, and 15,Figure 62-8) for nicks, cracks, dents, scratches, andvoids.

a. If cracks are found in the joint of the closuresat blade station 23.0, 28.0, 33.32, and 41.21(Figure 62-9), refer to paragraph 62-32 for repair.

b. If the root end closures have nicks, scratches,dents, and voids, refer to paragraph 62-32 for repair.

2. If the root end closure needs replacement, sendthe main rotor blade to a BHT approved blade repairfacility for repair.


NUMBER NOMENCLATURE

T75449-2 Tap Hammer


MATERIALS REQUIRED

NUMBER NOMENCLATURE



MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-363 Adhesive

BHT-407-MM-6

62-00-008 APR 2011 Rev. 30 Page 27ECCN EAR99

Figure 62-8. Main Rotor Blade Assembly407MM_62_0004_c01

4

1. Spacer assembly 2. Liner 3. Bushing 4. Fretting pad 5. Butt closure 6. ID tag 7. Nameplate 8. Forward closure 9. Erosion strip10. Spar assembly11. Tooling key12. Skin13. Trailing edge strip14. Decal15. Aft root closure16. Plate17. Screw18. Shim19. Screw

21. Weight assembly

22. Retainer assembly23. Threaded insert 24. Screw25. Tie-down plate

27. Erosion shield28. Screw29. Trim tab assembly30. Core

SEE DETAIL A

2

3

5

6

7

4

16

149

15

30

17

19

20

21

22

28

1312

21

18

26

24

1

25

18

2913

27

23

8

9

10

11 1

30 TO 40 IN-LBS(3.4 TO 4.5 Nm)

20. Cover

26. Cover assembly

Tooling keys are located between blade station65 to 75 and 135 to 145.

1

NOTE

DETAIL A

BHT-407-MM-6

62-00-00Page 28 Rev. 23 7 NOV 2006

Figure 62-9. Main Rotor Blade Closure — Repair407MM_62_0005

1. Butt closure

3. AFT root closure4. Main rotor blade

2. FWD root closure

BLADE

4

2

1

3STA24.25

BLADESTA28.0

BLADESTA41.21

BLADESTA23.0

BLADESTA33.32

BHT-407-MM-6


62-18. MAIN ROTOR BLADE — TRIM TABS —INSPECTION

1. Inspect trim tab assembly (29, Figure 62-8) forvoids and debonding.

a. Maximum allowable void between tab or tabskins is 1 square inch (6.45 cm²) per surface. Edgevoids must be sealed with adhesive (C-363).

b. Voids exceeding above limits will requirereplacement of trim tab (29) (paragraph 62-33).

2. Any trim tab (29) that is bent to such an extent itcannot be straightened, will require replacement oftrim tab (paragraph 62-33).

3. If trim tab is cracked, replace as per paragraph62-33.

62-19. MAIN ROTOR BLADE — TOOLING KEYAREA (UPPER SURFACE) — INSPECTION

The main rotor blade stainless steel erosion strip (9,Figure 62-8) has two cut-outs on the upper surface.

These two cut-outs serve as tooling keys (11) duringmanufacture of the blade. In the area of each of thetooling keys are cavities. These cavities areapproximately 0.50 inch (12.70 mm) wide, 10 inches(254 mm) long, 0.100 inch (2.54 mm) deep, andtapered at both ends. The cavities/tooling keys startapproximately 2 inches (50.8 mm) aft of the extremeleading edge and are located between blade station65 to 75 and 135 to 145. The cavities are filled with anaerodynamic filler to obtain a smooth surface.

Inspect the filler applied in the tooling key areas (11)for cracks and voids. If cracks and voids are found,repair as per paragraph 62-34.

62-20. MAIN ROTOR BLADE — EROSION STRIP— INSPECTION

1. Inspect erosion strip (9, Figure 62-8) for voids.

NOTE

Voids within 1 inch (25.4 mm) of each otherwill be considered as one void.

a. Voids exceeding 30.0 square inches(193.55 cm²) in area and 3 inches (76.2 mm)chordwise width require replacement of blade.

b. Edge voids not exceeding 0.250 inch(6.35 mm) deep and not within 0.500 inch (12.7 mm)of an acceptable void may be repaired (paragraph62-35).

c. Edge voids exceeding 0.250 inch (6.35 mm) indepth or closer than 0.50 inch (12.7 mm) to anacceptable internal void will require replacement of theblade.

d. Any main rotor blade that has exceeded therepair criteria may be sent to a Bell Helicopter Textron(BHT) approved blade repair facility for evaluation andpossible repair.

2. Inspect erosion strip (9) for nicks, dents, andscratches.

a. Non-sharp dents that do not exceed0.020 inch (0.508 mm) deep are acceptable withoutrepair.

b. Nicks, scratches, and sharp dents that do notexceed 0.012 inch (0.304 mm) are repairable(paragraph 62-35).

c. Nicks, scratches, and sharp dents exceeding0.012 inch (0.304 mm) deep require disposition fromProduct Support Engineering.


MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-363 Adhesive


NUMBER NOMENCLATURE

T75449-2 Tap Hammer

BHT-407-MM-6

62-00-00Page 30 Rev. 31 11 JUL 2011 ECCN EAR99

d. Non-sharp dents exceeding 0.020 inch(0.508 mm) deep require disposition from ProductSupport Engineering.

3. Inspect erosion strip (9) for cracks. Chordwiseoriented cracks in the erosion strip outboard of bladestation 135 are acceptable provided all of the followingconditions are met:

a. No chordwise crack may be within 0.5 inches(12.7 mm) of another chordwise crack.

b. Upon initial detection of a chordwise crackand every 50 hours thereafter until erosion stripreplacement, visually inpsect for evidence of voidsassociated with the crack. Either a spanwise paintcrack at the aft edge of the erosion strip or a locallyraised portion of the erosion strip would constitutevisual evidence of a void. No voids allowed.

c. Upon initial detection of a chordwise crackand every 100 hours thereafter until erosion stripreplacement, inspect for voids under the erosion stripadjacent to the crack using a bonding tap hammer(T75449-2). No voids allowed.

62-21. MAIN ROTOR BLADE — EROSION SHIELD— INSPECTION

1. Inspect the adhesive in the joint between theerosion shield (27, Figure 62-8) and the erosion strip(9) for erosion. If the adhesive is eroded, a cavity willbe created exposing the erosion shield leading edge,which could lead to debonding of the erosion shield. Ifthe adhesive in the joint between the erosion shieldand the erosion strip is eroded, repair per paragraph62-36.

NOTE


2. Inspect erosion shield (27) for voids.

a. Voids less than 3 square inches (19.35 cm²) inarea with chordwise width of less than 1 inch(25.4 mm) and more than 0.500 inch (12.7 mm) fromthe edge are acceptable without repair. The total areaof acceptable voids shall not exceed 6 square inches(38.71 cm²).

b. Voids exceeding 3 square inches (19.35 cm²)in area or having a chordwise width of more than

1 inch (25.4 mm) or closer than 0.500 inch (12.7 mm)to the edge require replacement of the blade.

c. Edge voids less than 0.500 inch (12.7 mm)deep are repairable (paragraph 62-36).

d. Edge voids exceeding 0.500 inch (12.7 mm)deep will require replacement of the blade.

3. Inspect erosion shield (27) for nicks andscratches.

a. Any nick or scratch that does not penetratethrough the erosion shield (27) is acceptable withoutrepair.

b. Any nick or scratch that penetrates throughthe erosion shield (27) will require the replacement ofthe blade.

4. Main rotor blades that have exceeded the repaircriteria may be sent to a BHT approved blade repairfacility for evaluation and possible repair.

62-22. MAIN ROTOR BLADE — UPPER ANDLOWER SKINS — INSPECTION

1. Inspect blade skins (12, Figure 62-8) for voids.

NOTE


a. Voids between the skin (12) and core (30) lessthan 5 square inches (32.26 cm²) in area each, with achordwise width less than 1 inch (25.4 mm), with atotal area less than 25.0 square inches (161.29 cm²)area are acceptable without repair.

b. Single voids exceeding 5 square inches(32.26 cm²) require the replacement of the blade.

c. Voids between skin (12) and spar assembly(10) less than 1/4 the width of the faying surface, lessthan 20.0 inches (508 mm) in length, more than0.500 inch (12.7 mm) from the edge of skin (14), andless than 15.0 square inches (96.77 cm²) in total areaeach side of the blade are acceptable without repair.

d. Voids between skin (12) and spar assembly(10) exceeding 1/4 the width of the faying surface, ormore than 20.0 inches (508 mm) in length, or less than0.500 inch (12.7 mm) from the edge of skin, or more

BHT-407-MM-6


than 15.0 square inches (96.77 cm2) total area oneither side of the blade require the replacement of theblade assembly.

e. Edge voids between skin (12) and sparassembly (10) will be repaired by standard injectionmethod (paragraph 62-37).

f. Voids between skin (12) and trailing edge strip(13) less than 1/4 the width of the faying surface, lessthan 16.0 inches (406 mm) in length, more than 0.500inch (12.7 mm) from the edge of the skin, and lessthan 8 square inches (51.61 cm²) in total area areacceptable without repair.

g. Voids between skin (12) and trailing edge strip(13) exceeding 1/4 the width of the faying surface, ormore than 16.0 inches (406 mm) in length, or less than0.500 inch (12.7 mm) from the edge of the skin, ormore than 8 square inches (51.61 cm²) in total arearequire replacement of the blade assembly.

h. Edge voids between skin (12) and trailingedge (13) less than 0.250 inch (6.35 mm) requirerepair (paragraph 62-37).

i. Edge voids between skin (12) and trailingedge (13) exceeding 0.250 inch (6.35 mm) depthrequire the replacement of the blade.

2. Inspect skin (12) for nicks, dents, gouges,scratches, and holes.

a. Nicks, dents, scratches, and gouges that donot break the fibers or cause delamination areacceptable without repair.

b. Nicks, dents, and scratches that penetrate theskin (12) are repairable (paragraph 62-37).

c. Holes in skin (12) not exceeding 3 inches(76.2 mm) in diameter are repairable (paragraph62-38).

d. Holes in the skin (12) exceeding 3 inches(76.2 mm) in diameter or outside the allowable patcharea will require replacement of the blade assembly.

3. Main rotor blades that have exceeded the repaircriteria may be sent to a BHT approved blade repairfacility for possible repair.

62-23. MAIN ROTOR BLADE — TRAILING EDGE— INSPECTION

NOTE

Refer to General Information Letter (IL)GEN-04-98 for the applicable shippinginformation and to obtain a Return MaterialAuthorization (RMA) number.

1. Inspect the trailing edge (13, Figure 62-8) fornicks or notches. If the depth of the nicks or notches isless than 0.125 inch (3.17 mm), repair as required(paragraph 62-39). Otherwise, send the bladeassembly to Bell Helicopter Textron (BHT) forevaluation and possible repair.

2. Inspect the trailing edge (13) for cracks. If cracksare found, send the blade assembly to BHT forevaluation and possible repair.

62-24. MAIN ROTOR BLADE — TIE-DOWN —INSPECTION

1. Inspect the tie-down plate (25, Figure 62-8) forcracks, deformation, and voids. Replace the tie-downif damage is found (paragraph 62-40).

62-25. MAIN ROTOR BLADE — UPPER PRODUCTBALANCE WEIGHT COVER —INSPECTION

1. Inspect the cover (20, Figure 62-8) for cracks anddeformation. Replace the cover if damage is found.Refer to paragraph 62-41 for removal and installation.

62-26. MAIN ROTOR BLADE — UPPER PRODUCTBALANCE WEIGHT RETAINER —INSPECTION

NOTE

Inspection criteria only required for aconditional inspection.

1. Inspect the retainer assembly (22, Figure 62-8)for cracks, deformation, and damaged threads.Replace the retainer assembly if damage is found.Refer to paragraph 62-42 for removal and installation.

BHT-407-MM-6

62-00-00Page 32 Rev. 31 11 JUL 2011 ECCN EAR99

62-27. MAIN ROTOR BLADE — LOWERPRODUCT BALANCE WEIGHT COVER —INSPECTION

NOTE


1. Inspect the cover assembly (26, Figure 62-8) forcracks, deformation, and damaged threads. Replacethe cover assembly if damage is found. Refer toparagraph 62-43 for removal and installation.

62-28. MAIN ROTOR BLADE — UPPER ANDLOWER PRODUCT BALANCE WEIGHTS —INSPECTION

NOTE


1. Inspect the weight assembly (21, Figure 62-8) forcracks and corrosion. Replace the weight assembly ifdamage is found. Refer to paragraph 62-44 forremoval and installation.

62-29. MAIN ROTOR BLADE — UPPER PRODUCTBALANCE COVER THREADED INSERT —INSPECTION

NOTE


1. Inspect threaded insert (23, Figure 62-8) forlooseness or damaged threads. Replace insert iflooseness or damage is found. Refer to paragraph62-45 for removal and installation.

62-30. MAIN ROTOR BLADE — REPAIR

NOTE

Parts that do not meet inspectionrequirements shall be repaired or replaced.Only the authorized repair instructionsgiven in this section shall be done. Whenno repair is given for the part, send bladeassembly to a Bell Helicopter Textron(BHT) approved blade repair facility orcontact Product Support Engineering.

62-31. MAIN ROTOR BLADE — RETENTION BOLTHOLES BUSHING LINER — REPAIR

1. Polish out any raised material on the liner (2,Figure 62-8) with India stone (C-464) flush with thesurrounding surface.

2. Remove all corrosion from the liner (2) with fineabrasive paper (C-423). After corrosion is removed,the inner diameter must be no more than 1.002 inches(25.45 mm). Small areas that can be repaired by localpolishing must not exceed 20% of the inner diametersurface area.

62-32. MAIN ROTOR BLADE — ROOT ENDCLOSURE — REPAIR

1. Repair nicks, dents, and scratches on closures(1, 2, and 3, Figure 62-9) by lightly sanding with 180grit abrasive paper (C-423) flush with the surroundingsurface.


MATERIALS REQUIRED

NUMBER NOMENCLATURE


C-464 India Stone


MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-308 Sealant

C-326 Denatured Alcohol


C-486 Cheesecloth

C-516 Clean Cloth

C-557 Erosion Tape

C-558 Adhesive Promoter

BHT-407-MM-6


2. Repair surface cracks at the joint of the closures(1, 2, and 3) by lightly sanding the surface crack with180 grit abrasive paper (C-423) flush with thesurrounding surface. Seal with sealant (C-308) andrefinish the area per paragraph 62-46.

3. Repair surface cracks at the joint of the forwardroot closure (2) at blade station 33.32 (Figure 62-9)using Method 1 or Method 2.

CAUTION

CRACKING OF THE FILLER APPLIED ATTHE JOINT BETWEEN THE EROSIONSTRIP AND THE FORWARD ROOTCLOSURE (2) AT BLADE STATION 33.32(FIGURE 62-9) IS CONSIDERED MINOR.HOWEVER, THE CRACK SHOULD BEREPAIRED AS SOON AS POSSIBLE TOAVOID POSSIBLE DEBONDING OF THEEROSION STRIP FROM THE SPAR IFEXPOSED TO RAIN OR WATER.

NOTE

Use care when installing erosion tape(C-557) to prevent air bubbles under tape.

a. Method 1:

The crack may be sealed with a bead ofsealant (C-308).

b. Method 2:

(1) Lightly abrade the area to receive theerosion tape (427-015-001-131), (3.00 inches(76.2 mm) wide X 5.50 inches (139.7 mm) long) using220 grit abrasive paper (C-423).

(2) Clean the sanded area with denaturedalcohol (C-326) and a clean cloth (C-516) orcheesecloth (C-486). Allow to dry.

(3) Brush apply a thin coat of 3M 86Aadhesive promoter (C-558) on the blade area toreceive the erosion tape and allow to dry for10 minutes.

(4) Center and apply the black erosion tape(C-557) to cover the crack.

62-33. MAIN ROTOR BLADE — TRIM TABS —REPAIR AND REPLACEMENT

1. Repair edge voids between blade skin (3,Figure 62-10) and trim tab assembly (1) as follows:

a. Mix adhesive (C-363) as per manufacturer’sinstructions.

b. Using a plastic spatula, fill void with adhesive(C-363).

c. Cure adhesive 24 hours at room temperatureusing clamp pressure as required.

2. Use abrasive paper (C-423) to sand out anysurface nicks or scratches in the trim tab assembly (1)and refinish as per paragraph 62-46.

NOTE

Repair or replacement of trim tab assemblywill require dynamic balancing of rotorsystem. Refer to BHT-407-MM-2,Chapter 18 for procedure.

3. Repair bent trim tab assembly (1) with noevidence of bond separation. Straighten tab withheavy mallet and heavy backup block or suitable tool.


MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-317 Adhesive


C-363 Adhesive


C-426 Masking Tape

C-486 Cheesecloth

406-015-037-129 Trim Tab Assembly

BHT-407-MM-6

62-00-00Page 34 Rev. 23 7 NOV 2006

Figure 62-10. Main Rotor Blade Trim Tab Assembly — Replacement407MM_62_0006


3. Skin

2. Main rotor blade

SEE DETAIL A

DETAIL A

3

2

1

3

1

CUT

0.125 IN. (3.175 mm)

BHT-407-MM-6


CAUTION

MAKE SURE THAT ONLY QUALIFIEDPERSONNEL DO THE FOLLOWINGPROCEDURE OR DAMAGE TO THEBLADE CAN OCCUR. GET AID FROM ANAPPROVED BLADE REPAIR FACILITY IFNECESSARY.

4. Replace trim tab assembly (1) as follows:

CAUTION

BE CAREFUL NOT TO TEAR ORSEPARATE THE PLIES OF FIBERGLASSSKIN DURING REMOVAL OF THE TRIMTAB ASSEMBLY (1).

NOTE

Replace trim tab assembly (1) if it iscracked, debonded, dented, or if it has abend that cannot be straightened.

a. Remove trim tab assembly (1, Detail A) bycutting a section off about 0.125 inch (3.175 mm)beyond the main rotor blade (2).

b. Using gun type electric heater, apply heat totrim tab assembly (1) while peeling trim tab off. Do notexceed 200°F (93°C).

c. Pull trim tab assembly (1) spanwise starting atthe corner, one side at a time. Use extreme care toprevent tearing or separating plies of fiberglass skin.

d. Apply masking tape (C-426) 0.50 inch(12.7 mm) to 1 inch (25.4 mm) outside the perimeter ofthe trim tab.

CAUTION

DO NOT SATURATE MAIN ROTORBLADE (2) WITH ALCOHOL. BONDDAMAGE MAY OCCUR.

e. Remove paint in the border area by sandingwith 120 to 180 grit abrasive paper (C-423) in aspanwise direction.

f. Remove primer with abrasive paper (C-423) ina spanwise direction.

g. Remove old adhesive from main rotor blade(2) with 120 to 180 grit abrasive paper (C-423) in aspanwise direction. It is not necessary to remove alladhesive unless contamination exists. Clean offresidue by wiping with clean cloth.

h. Remove masking tape (C-426) from the mainrotor blade (2).

i. Remove the peel-ply from the trim tabassembly (1). Use 120 to 180 grit abrasive paper(C-423) to make trim tab mating surface rough. Cleanthe mating surfaces with a clean dry cloth.

j. Use cheesecloth (C-486) moist withdenatured alcohol (C-326) to clean the blade and trimtab assembly surfaces. Allow surface to dry.

k. Mix adhesive (C-317) as per manufacturer’sinstructions.

l. Apply adhesive (C-317) to the mating surfacesof the blade (2) and the trim tab (1). Ensure the matingsurfaces are wet with adhesive (C-317).

m. Install the trim tab assembly (1) as far forwardon the main rotor blade (2) as it can go. Move the trimtab (1) back and forth to remove all trapped air frombetween the mating surfaces. Remove unwantedadhesive. Make the adhesive (C-317) into a smoothbead around the edge of the trim tab.

n. Using wooden blocks and clamps, apply apressure of 5 PSI (34.48 KPA) to the trim tabassembly (1).

o. Let the adhesive (C-317) cure for 24 hours atroom temperature, or 2 hours at 150 to 160°F (65.5 to71.1°C).

p. If necessary, blend in excess adhesive tocontour of the blade by sanding with 120 to 180 gritabrasive paper (C-423).

q. Refinish area per paragraph 62-46.

BHT-407-MM-6


62-34. MAIN ROTOR BLADE — TOOLING KEYAREA (UPPER SURFACE) — REPAIR

1. Repair cracks and voids in adhesive betweenleading edge erosion strip (1, Figure 62-11) and skin(7) in the fill and fair material of the tooling key (2) asfollows:

a. Apply masking tape (C-426) 0.50 inch(12.7 mm) outside the damaged perimeter of thetooling key (2).

b. Remove paint and primer with 120 to 180 gritabrasive paper (C-423) in a spanwise direction.

c. Remove loose adhesive from tooling key (2)with 120 to 180 grit abrasive paper (C-423) in aspanwise direction. Only remove the necessarycracked or loose adhesive. It is not necessary toremove all adhesive.

CAUTION

DO NOT SATURATE MAIN ROTORBLADE WITH ALCOHOL. BOND DAMAGEMAY OCCUR.

d. Clean off sanding residue by wiping withcheesecloth (C-486) dampened with denaturedalcohol (C-326).

e. Remove masking tape from around theoutside perimeter of tooling key (2).

f. Mix adhesive (C-317) as per manufacturer’sinstructions.

g. Apply adhesive (C-317) to the damagedtooling key (2) area as a fill and fair material.

h. Let the adhesive cure for 24 hours at roomtemperature, or 2 hours at 150 to 160°F (65.5 to71.1°C).

i. Using 180 grit abrasive paper (C-423), sandexcessive adhesive smooth to contour of main rotorblade.

j. Refinish area per paragraph 62-46.

62-35. MAIN ROTOR BLADE — EROSION STRIP— REPAIR

1. Repair edge voids between erosion strip (1,Figure 62-11) and spar assembly (6) as follows:

a. Prepare adhesive (C-363) as permanufacturer’s instructions.

b. Use polyethylene syringe (C-502) or plasticspatula and force adhesive (C-363) into void.

c. Let the adhesive cure for 24 hours at roomtemperature, or 2 hours at 150 to 160°F (65.5 to71.1°C).

2. Repair nicks and scratches in erosion strip (1) asfollows:

a. Use 120 to 180 grit abrasive paper (C-423) orsteel steel wool (C-411) to polish out nicks andscratches.

b. Polish to a finish of 63 rms or better, removingonly enough material to eliminate nicks and scratches.


MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-317 Adhesive



C-426 Masking Tape

C-486 Cheesecloth


MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-363 Adhesive

C-411 Steel Wool


C-502 Polyethylene Syringe

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 37

Figure 62-11. Main Rotor Blade Cross-Sectional View407MM_62_0007

1. Erosion strip

3. Tiedown

4. Trailing edge strip


6. Spar assembly

7. Skin

8. Core

NOTE

2. Tooling key

Tooling keys are located between blade

station 65 to 75 and 135 to 145.

SECTION A-A

A

A

ROTATED 90° CCW

21

54

3

876

2

4

7

BLADE

STA

24.25

BLADE

STA

30.00

1

1

BLADE

STA

41.21

BLADE

STA

144.00

BLADE

STA

199.50

BLADE

STA

204.00

BLADE

STA

210.00

BLADE

STA

203.00

1

BHT-407-MM-6


3. Repair the nickel plating that is on the erosionstrip from blade station 144 to 210 as follows:

a. Use 120 to 180 grit abrasive paper (C-423) orsteel wool (C-411) to polish out erosion of the nickelplating in a spanwise direction.

b. Polish to a finish of 63 rms or better, removingonly enough material to eliminate erosion.

62-36. MAIN ROTOR BLADE — EROSION SHIELD— REPAIR

1. Repair eroded adhesive in the joint between theerosion shield (27, Figure 62-8) and the erosion strip(9) as follows:

a. Use 180 grit abrasive paper (C-423) and sandsmooth the remaining adhesive.

b. Thoroughly clean the area to be repaired withdenatured alcohol (C-326).

c. Prepare fairing compound (C-323) permanufacturer’s instructions.

d. Use a plastic spatula and fill the cavity in thejoint between the erosion shield (27) and the erosionstrip (9) with fairing compound (C-323).

e. Once cured, sand smooth the filler with 220grit abrasive paper (C-423) and refinish area perparagraph 62-46.

2. Repair edge voids between erosion shield (27)and blade skin assembly (12) as follows:

a. Prepare adhesive (C-363) as permanufacturer’s instructions.

b. Use polyethylene syringe (C-502) or plasticspatula and force adhesive (C-363) into void.

c. Let the adhesive cure for 24 hours at roomtemperature, or 2 hours at 150 to 160°F (65.5 to71.1°C).

3. Repair nicks and scratches in erosion shield (27)as follows:

a. Use 120 to 180 grit abrasive paper (C-423) orsteel wool (C-411) to polish out nicks and scratches.

b. Polish to a finish of 63 rms or better, removingonly enough material to eliminate nicks and scratches.

c. Refinish area per paragraph 62-46.

62-37. MAIN ROTOR BLADE — UPPER ANDLOWER SKINS — REPAIR


MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-323 Fairing Compound

C-326 Deantured Alcohol

C-363 Adhesive

C-411 Steel Wool




MATERIALS REQUIRED

NUMBER NOMENCLATURE


C-317 Adhesive


C-363 Adhesive

C-404 Glass Cloth


C-426 Masking Tape

C-486 Cheesecloth

299-015-008-127 Skin Patch Material

BHT-407-MM-6


CAUTION

ANY REPAIR TO BLADE WILL REQUIREDYNAMIC BALANCING OF ROTORSYSTEM AS PER CHAPTER 18.

GREASE PENCILS WILL NOT BE USEDTO MARK THE BLADE. ONLY LEADPENCIL LINES WILL BE MADE, ASSHOWN. PENCIL MARKS OTHER THANTHOSE SPECIFIED IN INSTRUCTIONSCAN WEAKEN REPAIR.

NOTE

Damage is limited to 3 inches (76.2 mm) inany direction and the patch is limited to5 inches (127 mm) in diameter.

1. Repair damage that does not penetrate the outerlayer of woven glass cloth as follows:

CAUTION

EXCESSIVE SANDING WILL WEAKENBLADE SKIN . SAND ONLY UNTILPRIMER IS REMOVED.

a. Use 180 grit abrasive paper (C-423) andremove paint and primer from blade assembly (3,Figure 62-12) in an area approximately 3 inches(76.2 mm) around the perimeter of the damage (2).

b. Clean sanded area with cheesecloth (C-486)dampened with aliphatic naphtha (C-305).

c. Cut a piece of glass cloth (C-404) largeenough to cover the damaged area plus 1 inch(25.4 mm) all around.

d. Mix adhesive (C-363) as per manufacturer’sinstructions.

e. Apply wet layer of glass cloth (C-404) andadhesive (C-363) to damaged area.

f. Let the adhesive (C-363) cure for 24 hours atroom temperature, or for 2 hours at 150 to 160°F (65.5to 71.1°C).

g. Use 180 grit abrasive paper (C-423) and sandarea smooth.

h. Refinish area per paragraph 62-46.

2. Repair damage passing through both skins withcore damage less than 1 square inch (6.45 cm²) in therepairable area as shown on Figure 62-12 as follows:

NOTE

The patch shall cover the damage by 1 inch(25.4 mm) minimum all around and shall becircular or oblong in shape.

a. Position blade assembly (3) for access todamaged area (2). Support blade assembly to preventmovement or droop.

b. Make a template (4) to a diameter of 2 inches(50.8 mm) larger than the damaged area (2) andposition it on blade assembly (3). Position inner circleto enclose damage, as shown in Figure 62-12. Holdtemplate to keep from slipping, and draw a pencil linearound the outer circle as shown.

CAUTION

EXCESSIVE SANDING WILL WEAKENBLADE SKIN . SAND ONLY UNTILPRIMER IS REMOVED.

c. Starting with 180 grit abrasive paper (C-423)and finishing with 200 grit abrasive paper (C-423),sand paint and primer from blade assembly (3) withinguided circle. Sand until yellow primer and anydamage material raised above normal contour ofblade is removed. Do not sand fibers.

d. Wipe off all sanding dust.

e. Use template (4) and redraw guide circle.

f. Use masking tape (C-426) (5) to mask aroundthe outside of guide circle.

BHT-407-MM-6

62-00-00Page 40 Rev. 23 7 NOV 2006

Figure 62-12. Main Rotor Blade Skin — Repair (Sheet 1 of 2)407MM_62_0008

GUIDE CIRCLE

PENCIL LINE

34

5

GUIDE CIRCLE

PENCIL LINE

MINIMUM AREA FOR

PAINT REMOVAL

2

3

1

EROSION

STRIP

1.00 IN. (25.4 mm)

MINIMUM

1.50 IN. (38.1 mm)

MINIMUM

3.00 IN. (76.2 mm) MINIMUM

5.00 IN. (127.0 mm) MAXIMUM

No patches allowed

Minimum distance between patches: 1.50 IN. (38.1 mm)

Skin patch size:

BS

197.00

BS

55.00

BS

24.25

BS

210.00

BS

182.00

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 41

Figure 62-12. Main Rotor Blade Skin — Repair (Sheet 2 of 2)407MM_62_0010

2. Damage

7. Blade skin6. Patch5. Masking tape4. Template3. Blade assembly

1. Paint removal area

6

2 IN. (50.8 mm)

GUIDE CIRCLEPENCIL LINE

6

7

BHT-407-MM-6


CAUTION

SURFACE TO BE BONDED MUST BECLEAN, DRY, AND FREE OFFINGERPRINTS AND ALL FOREIGNMATERIAL.

g. Dampen clean cheesecloth (C-486) withdenatured alcohol (C-326) and clean inside maskedarea. Wipe with clean, dry cheesecloth (C-486) beforealcohol (C-326) evaporates.

NOTE

For correct skin patch material, use skinpatch 299-015-008-127.

The part number and arrow for the directionof installation are identified on the outersurface of the patch material.

h. Cut the skin patch (6) to the diameter of thetemplate (4) as per step b.

i. Remove the peel ply if applicable from theskin patch (6) and make the inner surface of the skinpatch rough with 180 grit abrasive cloth or paper(C-423).

j. Use clean cheesecloth (C-486) dampenedwith alcohol (C-326) to the sanded area of the skinpatch (6) and blade skin. Dry area with clean, drycheesecloth (C-486).

NOTE

Pot life is 15 minutes at 75°F (23.8°C). It isshorter at higher temperatures.

k. Mix adhesive (C-317) as per manufacturer’sinstructions.

l. Use a clean spatula, tongue depressor, or1 inch (25.4 mm) paint brush and apply a light coat ofadhesive (C-317) to the blade skin (7) within the guidecircle and to the underside of the skin patch (6).

m. With the stenciled arrow pointing outboard,center the skin patch (6) within the guide circle. Slideback and forth slightly underhand pressure to even out

adhesive (C-317). Use light hand pressure to squeezefrom the center to the edge to work out any airbubbles.

n. Use clean cheesecloth (C-486) dampenedwith denatured alcohol (C-326) and remove excessiveadhesive (C-317).

o. Prevent patch movement by placing maskingtape (C-426) over the edge of the skin patch (6).

p. Let the adhesive (C-317) cure for 24 hours atroom temperature, or for two hours at 150 to 160°F(65.5 to 71.1°C). Apply heat locally at not more thanthe maximum temperature.

q. Use 180 grit abrasive cloth or paper (C-423) tosand the adhesive (C-317) around the patch to smoothcontour.

r. Refinish the area as per paragraph 62-46.

62-38. MAIN ROTOR BLADE — UPPER ANDLOWER SKINS AND CORE — REPAIR


MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-317 Adhesive

C-326 Alcohol

C-423 Abrasive Cloth or Paper

C-426 Masking Tape

C-486 Cheesecloth

299-015-008-127 Skin Patch

299-015-008-111 Core Patch 0.25 inch (6.35 mm) thick



BHT-407-MM-6


CAUTION

NO PATCHING IS ALLOWED OVERSPAR OR TRAILING EDGE STRIP.

ANY REPAIR TO BLADE WILL REQUIREDYNAMIC BALANCING OF ROTORSYSTEM AS PER CHAPTER 18.

GREASE PENCILS WILL NOT BE USEDTO MARK THE BLADE. ONLY LEADPENCIL LINES WILL BE MADE, ASSHOWN. PENCIL MARKS OTHER THANTHOSE SPECIFIED IN INSTRUCTIONSCAN WEAKEN REPAIR.

NOTE

Core patches are not allowed closer than0.75 inch (19.05 mm) to the leading edgespar or 0.500 inch (12.7 mm) to the trailingedge spar. Distance between patches mustbe at least 2.5 inches (63.5 mm) chordwiseand 7.25 inches (184.15 mm) spanwisefrom the patch of any kind.

The core skin patch shall cover the damageby 1 inch (25.4 mm) all around and shall becircular in shape.

Damage is limited to 3 inches (76.2 mm) inany direction and the core patch is limitedto 5 inches (127 mm) in diameter.

Damage that does not pass completelythrough the blade assembly may berepaired with a single core patch.

Damage that passes completely throughthe blade assembly will be repaired byinstalling core patches from the top andbottom sides of the blade assembly. Installthe larger diameter and depth core patchfirst, as shown in Figure 62-13.

1. Position blade assembly (1, Figure 62-13) foraccess to damaged area (3) support blade assemblyto prevent movement or droop.

2. Make a template (2) to enclose the diameter ofthe damaged area (3) and position it on bladeassembly (1). Position inner circle to enclose damage,as shown in Figure 62-13. Hold template to keep fromslipping, and draw a pencil line around the inner circleas shown. This circle will become circle “A”.

CAUTION

SAND ONLY UNTIL PRIMER ISREMOVED.

3. Starting with 180 grit abrasive paper (C-423) andfinishing with 200 grit abrasive paper (C-423), sandpaint and primer from blade assembly (1) within anarea of approximately 3 inches (76.2 mm) outside ofguide circle. Sand until yellow primer and anydamaged material raised above normal contour ofblade is removed. Do not sand fibers.

4. Wipe off all sanding dust.

5. Use template (2) and redraw guide circle.

CAUTION

DURING ROUTING OPERATIONS, LONGDIMENSIONS OF ROUTER BASE SHALLBE KEPT IN SPANWISE DIRECTION.

END MILLS WILL BURN OUT IF USED TOCUT BLADE ASSEMBLY SKIN.

6. Using router, install rasp-type bit in router and setdepth to 0.02 inch (0.508 mm). Route a completecircle (4) through skin inside of and following circle “A”.

7. Peel damaged skin (5) from core (6).

BHT-407-MM-6

62-00-00Page 44 Rev. 23 7 NOV 2006

Figure 62-13. Main Rotor Blade Core — Repair (Sheet 1 of 2)

CIRCLE A

ROUTING GUIDE

PENCIL LINE

12MINIMUM AREA

FOR PAINT

REMOVAL3

1.00 IN.

(25.4 mm)

No patches allowed

CIRCLE B

MASKING GUIDE

PENCIL LINE

WAFERS

3.00 X 0.47 IN.

(76.2 X 11.94 mm)

CORE PATCH

3.00 X 0.75 IN.

(76.2 X 19.05 mm)

CORE PATCH

2.50 IN. (63.5 mm)

MINIMUM

0.50 IN. (12.7 mm)

MINIMUM

7.25 IN. (184.15 mm)

MINIMUM

4.00 IN.

(101.6 mm)

6.20 IN.

(157.48 mm)

2.50 IN. (63.5 mm) CHORDWISE

7.25 IN. (184.15 mm) SPANWISE

Minimum distance between skin and core patches:

4.00 IN.

(101.6 mm)

0.75 IN.

(19.05 mm)

BS

197.00

BS

210.00

BS

182.00

BS

96.00

BS

55.00

BS

24.25

BS: Blade Station

Damage limit: 3.00 IN. (76.2 mm) any direction

Core patch limit: 3.00 IN. (76.2 mm) diameter

407MM_62_0011

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 45

Figure 62-13. Main Rotor Blade Core — Repair (Sheet 2 of 2)407MM_62_0009

11

CIRCLE BMASKING GUIDE

PENCIL LINE

MINIMUM AREA FOR

PAINT REMOVAL

CIRCLE BMASKING GUIDE

PENCIL LINE

CIRCLE AROUTING GUIDE

PENCIL LINE

2. Template

11. Masking tape

10. Core wall

9. Blade skin

8. Core plug

7. Patch

6. Core

5. Damaged skin

4. Routed circle

3. Damaged area

1. Blade assembly

2

10

9

CORE, ROUTED

TO CIRCLE A

7

8

6

54

CIRCLE AROUTING GUIDE

PENCIL LINE

BHT-407-MM-6


NOTE

The thickness of the core patch must besufficient to repair all damage or extendmore than halfway through the blade, sothat the remaining damage can be repairedfrom the opposite side.

Core patches have a thin layer of fiberglassbonded to one side. This will be bonded tothe end cells at the bottom of the cutoutarea. Core patches can be stacked forthickness.

8. Obtain a core patch no larger than necessary forrepairing damage.

9. Measure core thickness at trailing edge of routedcircle.

10. Select core patch of the appropriate thickness forrepair.

11. Install end mill in router. Set end mill to depth ofplug thickness of core patch, as shown inFigure 62-13.

12. First route a complete circle following inside ofcircle “A”. Route out remainder of core moving routerin a chordwise direction.

13. Remove all cuttings and sanding dust from repairarea.

14. Make a template (2) 2 inches (50.4 mm) largerthan the hole. Use template (2) and draw circle “B”.

15. Cut a circular patch from the core material. Thepatch must fit the hole loosely with a 0.0625 inch(1.5875 mm) gap all around. Use 180 grit abrasivepaper (C-423) to make surfaces of the core wall (10)rough.

NOTE

The part number and arrow for direction ofinstallation are identified on the outersurface of the patch material.

16. Cut skin patch material (299-015-008-127) to adiameter 2 inches (50.8 mm) larger than the hole.Remove the peel-ply if applicable and make the innersurface rough with 180 grit abrasive paper (C-423).

17. Put on cotton gloves until repair is complete.

CAUTION

CARE SHOULD BE TAKEN TO PREVENTDENATURED ALCOHOL (C-326) FROMENTERING CORE AREA OF THE BLADE.SPILLAGE SHOULD BE AVOIDED.

18. Use clean cheesecloth (C-486) dampened withdenatured alcohol (C-326) and clean blade skin (9)inside masked area. Also, clean the underside of thepatch (7). Wipe with clean, dry cheesecloth (C-486)before denatured alcohol (C-326) evaporates.

19. Mix adhesive (C-317) as per manufacturer’sinstructions.

CAUTION

ADHESIVE SHOULD NOT BE PACKEDINTO CELLS OF BLADE CORE OR PLUGPATCH. EXCESS ADHESIVE CAN CAUSEBLADE TO BE OUT OF BALANCE.

NOTE

Pot life of adhesive is 15 minutes at 75°F(23.8°C). It is shorter at highertemperatures.

20. Use a clean spatula, tongue depressor, or 1 inch(25.4 mm) paint brush and apply adhesive (C-317) tothe fiberglass side of the core patch and around thecircumference of the patch and hole. Install the corepatch into hole.

21. Use a spatula or brush and apply adhesive(C-317) to the skin patch and mating surfaces of theblade skin. Ensure the mating surfaces are wet withadhesive.

22. Install the skin patch centered on the holes.Ensure the arrow on the outer surface of the patch ispointed outboard. Hold patch in position with strips ofmasking tape (C-426).

23. Let the adhesive (C-317) cure for 24 hours atroom temperature, or for 2 hours at 150 to 160°F (65.5

BHT-407-MM-6


to 71.1°C). Apply heat locally and not more than themaximum temperature. The heat cure procedure isrecommended for the maximum bond strength.

24. Use 180 grit abrasive paper (C-423) and sand theadhesive (C-317) around the patch to smooth contour.

25. Refinish area per paragraph 62-46.

62-39. MAIN ROTOR BLADE — TRAILING EDGE— REPAIR

1. Repair edge voids between the blade skin (2,Figure 62-14) and the blade trailing edge strip (1) asfollows:

a. Mix adhesive (C-363) as per manufacturer’sinstructions.

b. Use a polyethylene syringe (C-502) or plasticspatula to force adhesive (C-363) into the void.

c. Let the adhesive (C-363) cure for 24 hours atroom temperature, or for 2 hours at 150 to 160°F (65.5to 71.1°C). Apply heat locally and not more than themaximum temperature. The heat cure procedure isrecommended for the maximum bond strength.

2. Repair nicks and notches in the extreme bladetrailing edge strip (2) less than 0.125 inch (3.17 mm)chordwise as follows:

a. Carefully sand the area locally to removeloose material and broken fibers. Use 180 abrasivepaper (C-423).

b. Mix adhesive (C-317) as per manufacturer’sinstructions.

c. Fill in the notched area and blended fiberswith adhesive using a spatula.

d. Let adhesive (C-317) cure for 24 hours atroom temperature.

e. Sand excess adhesive flush to contour on theupper, lower, and trailing edge surfaces using 180 gritabrasive paper (C-423) up to 2 inches (50.8 mm) onboth sides of the damaged area, as shown inFigure 62-14.

f. Clean sanded area with cheesecloth (C-486)saturated with aliphatic naphtha (C-305).

g. Refinish repaired area (paragraph 62-46).

62-40. MAIN ROTOR BLADE — TIE-DOWN —REPAIR


MATERIALS REQUIRED

NUMBER NOMENCLATURE


C-317 Adhesive

C-363 Adhesive

C-404 Glass Cloth


C-486 Cheesecloth



MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-317 Adhesive


C-326 Alcohol


NAS7503-3 Screw

400-015-014-101 Tie-down

BHT-407-MM-6

62-00-00Page 48 Rev. 23 7 NOV 2006

Figure 62-14. Main Rotor Blade Trailing Edge — Repair407MM_62_0013

2. Blade skin1. Blade trailing edge strip

2

2.00 IN.(50.8 mm)

2.00 IN.(50.8 mm)

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 49

1. Sand area on top of the blade in area of screws(8, Figure 62-15) with 180 grit abrasive cloth or paper(C-423) to gain access to screws.

2. Using gun-type electric heater, heat area aroundscrews (8) at a temperature not to exceed 160°F(71°C) for 2 minutes.

3. Remove screws (8).

4. Heat tiedown (9) as per procedure in step 2.

5. Clamp plier wrench securely on tiedown (9).

6. Using hammer, remove tiedown (9) by hittingclamp end of plier wrench in a direction from theleading edge towards the trailing edge.

7. Using small file, clean hole vacated by tiedown(9) in tip end of main rotor blade.

8. Blow out all loose residue from hole in tip end ofmain rotor blade.

9. Using a squeeze bottle containing denaturedalcohol (C-326), squirt into hole in tip end of main rotorblade that is to receive serviceable tiedown (9).

10. Blow out all residues with denatured alcohol(C-326).

11. Position serviceable tiedown (9) in tip end of mainrotor blade.

12. Using slender, sharp pointed center punch,estimate center of each screw (8) hole for tiedown (9).Using hammer, hit positioned center punch firmly,marking both holes centers on tiedown (9).

13. Using No. 7 drill, drill two holes in tiedown (9)utilizing two punch marks as centers.

14. Using 10-32 UNF tap, tap the two drilled holes.

15. Prepare adhesive (C-317) as per manufacturer’sinstructions.

16. Using spatula, apply adhesive (C-317) to matingsurface of tiedown (9) and main rotor blade.

17. Install tiedown (9) in main rotor blade.

18. Install screws (8) .

19. Allow adhesive (C-317) to cure 24 hours at roomtemperature.

20. Fill and fair area where screws (8) are installedwith fairing compound (C-323). Sand smooth tocontour with 180 grit abrasive cloth or paper (C-423).

21. Refinish repaired area as per paragraph 62-46.

62-41. MAIN ROTOR BLADE — UPPER PRODUCTBALANCE COVER — REMOVAL/INSTALLATION

1. Remove cover (3, Figure 62-15) as follows:

a. Remove screws (1 and 2), attaching cover (3),weights (4), shims (5), and retainer (6) to main rotorblade and remove cover (3).

b. Remove any loose filler material in recess inthe blade. Sand recess area lightly with 180 gritabrasive cloth or paper (C-423).


MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-308 Sealant


C-339 Ethyl Alcohol


C-460 Adhesive Tape

C-486 Cheesecloth

NAS7503L2 Screw (1)

406-015-106-101 Cover (3)

T

BHT-407-MM-6


Figure 62-15. Main Rotor Blade Tip Components

NO OBJECT BEYOND THIS POINT 407MM_62_0014_c02

2

3

5

6

7

414

9

15

12

1

13

8

10

11

30 TO 40 IN-LBS(3.4 TO 4.5 Nm)

Fill the screw holes and the countersink with adhesive (C-317).

Apply adhesive (C-317) to the faying surfaces of the fiberglass cover (16) and the blade.

NOTES1

2

ScrewScrewCoverWeightShimRetainerThreaded insertScrewTiedownCoverShimWeightErosion shieldScrewTrim tab assemblyFiberglass cover

1.2.3.4.5.6.7.8.9.

10.11.12.13.14.15.16.

ADHESIVE (C-317)2

16

1

BLADE

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 51

NOTE

If cover is to be reused, make note of thelocation and quantity of shims. This willhelp maintain cover flushness.

c. Remove any old sealant from cover (3) bysanding lightly with abrasive cloth or paper (C-423).

d. Clean sanding residue from cover (3) andblade recess with clean cheesecloth (C-486)dampened with ethyl alcohol (C-339). Wipe dry withcheesecloth (C-486).

e. Adjust laminated shims (5) as necessary (peelto subtract, add to increase) to ensure final installationof cover (3) surface is flush with contour of bladesurface within 0.002 inch (0.0508 mm).

f. Place shims (5) (12 maximum), weights (4),and retainer (6) in position.

g. Place clean cover (3) in position on main rotorblade.

h. Temporary install screws (1 and 2) to securecover (3) .

i. Ensure surface of cover (3) is flush withcontour of blade surface within 0.002 inch (0.0508mm).

j. If tolerance is acceptable, proceed to step lbelow.

k. If tolerance is not acceptable, repeat step d tostep h.

l. Coat cover (3) with adhesive tape (C-460) toprevent sticking with adhesive.

m. Prepare fairing compound (C-323) as permanufacturer’s instructions.

n. Using spatula, fill gap between faying surfaceof main rotor blade and cover (3) with fairingcompound (C-323).

o. Cure fairing compound (C-323) 24 h ours atroom temperature.

p. Remove adhesive tape (C-460) from cover(3).

q. Fair fairing compound (C-323) to matchcontours using 180 grit abrasive cloth or paper(C-423).

r. Remove screws (1 and 2) and cover (3).

s. Apply sealant (C-308) to cover (3) and installcover in position in main rotor blade.

t. Apply sealant (C-308) under heads of screws(1 and 2) and install screws to secure cover (3) .

u. Refinish repaired area as per paragraph62-46.

62-42. MAIN ROTOR BLADE REPAIR — UPPERPRODUCT BALANCE WEIGHT RETAINER— REMOVAL/INSTALLATION

1. Replace retainer (6, Figure 62-15) as follows:

a. Remove screws (1 and 2) attaching cover (3),weight (4), shim (5), and retainer (6) to main rotorblade and remove cover (3).

CAUTION

REPLACE RETAINER (6) WITH THESAME PART NUMBER ASSEMBLY. IFRETAINER IS NOT REPLACED WITHTHE SAME PART NUMBER ROTORTRACK, BALANCE WILL NOT BEACHIEVED.

b. Replace retainer (6) and reinstall as perparagraph 62-41.

T


MATERIALS REQUIRED

NUMBER NOMENCLATURE

406-015-038-109 Retainer (Aluminum) (6)

406-015-038-111 Retainer (Cres Steel) (6)

406-015-040-013 Retainer (Tungsten) (6)

T

BHT-407-MM-6

62-00-00Page 52 Rev. 23 7 NOV 2006

62-43. MAIN ROTOR BLADE REPAIR — LOWERPRODUCT BALANCE WEIGHT COVER —REMOVAL/INSTALLATION

1. Remove trailing edge balance cover (10,Figure 62-15) as follows:

a. Remove screws (14) while supporting cover(10), shims (11), and weight (12).

b. Remove cover (10), shims (11), and weight(12).

c. Remove fill and fair adhesive on m ain rotorblade by sanding with 180 grit abrasive cloth or paper(C-423).

d. Clean sanding residue from main rotor bladewith clean cheesecloth (C-486) dampened with ethylalcohol (C-339). Wipe dry with cheesecloth (C-486).

CAUTION

REPLACE COVER (10) WITH THE SAMEPART NUMBER ASSEMBLY. IF COVER IS

NOT REPLACED WITH THE SAME PARTNUMBER ROTOR TRACK, BALANCEWILL NOT BE ACHIEVED.

2. Install trailing edge balance cover (10) as follows:

a. Adjust laminated shims (11) as necessary(peel to s ubtract, add to i ncrease) to ens ure finalinstallation of cover (10) surface is flush with contourof blade surface within 0.002 inch (0.0508 mm).

b. Place shims (11) (9 maximum) and weights(12) in position.

c. Place clean cover (10) in position on m ainrotor blade.

d. Temporary install screws (14) to secure cover(10) .

e. Ensure surface of cover (10) is flush withcontour of blade surface within 0.002 inch (0.0508mm).

f. Remove screws (14) and remove cover (10),shims (11), and weights (12).

g. Apply sealant (C-308) to cover (10) and installcover, shim (11), and weights (12) in position in mainrotor blade.

h. Apply sealant (C-308) under heads of screws(14) and install screws to secure cover (10) .

i. Prepare fairing compound (C-323) permanufacturer’s instructions.

j. Using spatula, fill gap between surface ofmain rotor blade and cover (10) with fairing compound(C-323).

k. Cure fairing compound (C-323) 24 h ours atroom temperature.

l. Match fairing compound (C-323) to contoursusing 180 grit abrasive cloth or paper (C-423).

m. Refinish repaired area as per paragraph62-46.


MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-308 Sealant


C-339 Ethyl Alcohol


C-486 Cheesecloth

NAS517-3-1 Screw (14)

120-034-26-16 Shim (11)

406-015-043-101 Cover (Aluminum) (10)

406-015-043-103 Cover (Cres) (10)

T

T

BHT-407-MM-6

62-00-00ECCN EAR99

62-43A.MAIN ROTOR BLADE REPAIR —PRODUCT BALANCE FIBERGLASSCOVER — REMOVAL/INSTALLATION

NOTE

The fiberglass cover (16, Figure 62-15) isused when the other covers are too heavyto balance the blade.

1. Remove the fiberglass cover (16) as follows:

a. Carefully remove the fiberglass cover (16) witha spatula.

b. Remove excess fairing compound from themain rotor blade with 180 grit abrasive paper (C-423).

c. Clean the area with a clean cheesecloth(C-486) dampened with ethyl alcohol (C-339). Dry witha cheesecloth (C-486).

CAUTION

REPLACE THE FIBERGLASS COVERWITH A COVER THAT HAS THE SAMEPART NUMBER. IF NOT, THE CORRECT

BALANCE OF THE BLADE WILL NOT BEDONE.

2. Install the fiberglass cover (16) as follows:

a. Inside the weight pocket, put masking tape(C-426) on the screw holes to prevent a flow ofadhesive in the pocket.

b. Fill the screw holes and the countersinks withadhesive (C-317), as shown in Figure 62-15.

CAUTION

DO NOT EXCEED THE MAXIMUMPERMITTED TEMPERATURE WHEN YOUHEAT THE BLADE OR DAMAGE TO THEBLADE MAY OCCUR.

c. Let the adhesive (C-317) cure for 24 hours atroom temperature, or 2 hours at 150 to 160°F (65.5 to71.1°C).

d. Remove masking tape from the weight pocket.

e. Apply adhesive (C-317) to the faying surfacesof the fiberglass cover (16) and the blade.

f. Install the fiberglass cover (16) on the blade.Make sure the cover is flush with the contour of theblade.

g. Prepare fairing compound (C-323) per themanufacturer’s instructions.

h. Use fairing compound (C-323) to make thecontour of the fiberglass cover (16) smooth.

i. Let the fairing compound (C-323) cure for 24hours at room temperature.

j. Use 180 grit abrasive paper (C-423) to makethe fairing compound and the mating surfaces of theblade smooth.

k. Refinish the repaired area as per paragraph62-46.


MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-317 Adhesive


C-339 Ethyl Alcohol


C-426 Masking Tape

C-486 Cheesecloth

16 FEB 2012 Rev. 34 Page 52A/52B

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 53

62-44. MAIN ROTOR BLADE REPAIR — UPPERAND LOWER PRODUCT BALANCEWEIGHTS — REMOVAL/INSTALLATION

CAUTION

REPLACE WEIGHTS (4 AND 12 ,FIGURE 62-15) WITH THE SAME PARTNUMBER ASSEMBLY. IF WEIGHT IS NOTREPLACED WITH THE SAME PARTNUMBER, ROTOR TRACK BALANCEWILL NOT BE ACHIEVED.

1. Remove and install product balance weight (4,Figure 62-15) as per paragraph 62-41.

2. Remove and install product balance weight (12)as per paragraph 62-43.

62-45. MAIN ROTOR BLADE — UPPER PRODUCTBALANCE COVER THREADED INSERT —REPAIR

1. Replace threaded insert (7, Figure 62-15) asfollows:

a. Remove eight screws (1) and cover (3) withweights (4), screws (2), shims (5), and retainer (6)attached.

b. Remove defective thread insert (7).

CAUTION

DO NOT SATURATE MAIN ROTORBLADE WITH DENATURED ALCOHOL(C-326). BOND DAMAGE MAY OCCUR.

c. Clean area where threaded insert (7) wasremoved with 180 grit abrasive cloth or paper (C-423).

d. Clean with clean cheesecloth (C-486)dampened with denatured alcohol (C-326). Allow to airdry.

e. Prepare adhesive (C-363) as permanufacturer’s instructions.

f. Using spatula, apply adhesive (C-363) tooutside of threaded insert (7) and screw threadedinsert into hole.

g. Wipe excess adhesive (C-363) from threadedinsert (7) using clean cheesecloth (C-486), makingsure inside threads of t hreaded insert are free ofadhesive (C-363).

h. Cure adhesive (C-363) for 24 hours at roomtemperature.


MATERIALS REQUIRED

NUMBER NOMENCLATURE

406-015-022-101 Weight (Cres Steel)(4 and 12)

406-015-022-103 Weight (Tungsten)(4 and 12)

406-015-022-105 Weight (Aluminum)(4 and 12)


MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-326 Alcohol

C-363 Adhesive


C-486 Cheesecloth

MS124735 Insert


MATERIALS REQUIRED (Cont)

NUMBER NOMENCLATURE

BHT-407-MM-6

62-00-00Page 54 Rev. 23 7 NOV 2006

i. Install eight screws (1) and cover (3) withweights (4), screws (2), shims (5), and retainer (6) asper paragraph 62-41.

62-46. MAIN ROTOR BLADE — PAINTREFINISHING

CAUTION

EXTREME CARE MUST BE USEDDURING SANDING TO PREVENTDAMAGE TO BLADE GLASS SKINFIBERS.

NOTE

The only paint refinishing authorized istouch-up of repaired area. This restriction isnecessary to mai ntain lightning protectionand rotor track and balance.

The paint coating system for the compositeblade consists of a u rethane compatible

primer, copper-filled polyurethaneconductive coating and aliphaticpolyurethane paint. The copper-filledpolyurethane conductive coating isintended as a lightning protective coatingand a static bleed off coating on thecomposite blade.

1. Touch up and refinish main rotor blade as follows:

a. Thoroughly sand area to be refinished with320 grit abrasive cloth or paper (C-423).

b. Remove sanding residue with cheesecloth(C-486) dampened with toluene (C-306). Wash bladewith detergent soap as per MIL-C-18687 or equivalent.Achieve water break free surface, which will beevident by continuous unbroken film of water onsurface after thoroughly rinsing soap from surface.

NOTE

Do not touch the main rotor blade with barehands after it has been cleaned.

c. Use cleaning compound (C-318) to cleanmetal areas.

d. Apply alcoholic phosphoric cleaner (C-344)with a brush or swab to clean stainless steel surfaces.Let the solution stay on the surface for one to threeminutes. Flush the area fully and dry with clean cloth.

e. Use masking tape (C-426) to mask off area tobe refinished.

f. Mix epoxy polyamide primer (C-204) or(C-246) as per manufacturer’s instructions.

CAUTION

PRIMER SHALL BE OVERCOATEDWITHIN 8 HOU RS FOLLOWINGAPPLICATION. IF P RIMER IS NOTOVERCOATED WITHIN 8 HOURS, THEPRIMER MUST BE SCUFF SANDEDWITH ABRASIVE PAD (C-407) AND AMIST COAT OF EPOXY POLYAMIDEPRIMER (C-204) /EPOXY PRIMERCOATING (C-246) MUST BE ADDED.


MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-204 Epoxy Polyamide Primer

C-245 Polyurethane Coating

C-246 Epoxy Primer Coating

C-306 Toluene


C-344 Alcoholic Phosphoric Cleaner

C-407 Abrasive Pad


C-426 Masking Tape

C-486 Cheesecloth

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 55

g. Apply a coat of epoxy polyamide primer(C-204)/epoxy primer coating (C-246) with a minimumthickness of 1 mil (25.4 μm).

h. Allow epoxy polyamide primer (C-204)/epoxyprimer coating (C-246) to dry at room temperature aminimum of 1 hour to a maximum of 8 hours.

i. If overcoating, epoxy polyamide primer(C-204)/epoxy primer coating (C-246) cannot beaccomplished in time allowed. Blade surface shall bethoroughly sanded with abrasive pad (C-407) andreprimed.

j. Ensure blade has been primed as per step gthrough step i.

NOTE

As an alternate, it is permissible to touch uptop coat area with acrylic lacquer asoutlined in step n.

k. Mix polyurethane coating (C-245) as permanufacturer’s instructions.

l. Immediately prior to applying polyurethanecoating (C-245), wipe area to be painted with tack rag.

m. Final topcoat:

(1) Upper surfaces. Apply two or threecoats (as applicable) in order to attain topcoatthickness of 1.2 to 1.5 mils (30.48 to 38.10 μm) ofpolyurethane coating (C-245) MIL-C-85285,FED-STD-595 color number 27925, semigloss white.Allow to dry minimum of 30 minutes, then applyanother coat.

(2) Upper surface high visibility. Apply twocoats on top of the upper surface paint in order toattain topcoat thickness of 1.2 to 1.5 mils (30.48 to38.10 μm) of polyurethane coating (C-245)MIL-C-85285, FED-STD-595 color number 12197,gloss orange. Allow to dry a minimum of 30 minutes,then apply another coat.

(3) Lower surface and root end closures.Apply two coats on the bottom of the lower surface.Paint in order to attain topcoat thickness of 1.2 to 1.5

mils (30.48 to 38.10 μm) of polyurethane coating(C-245) MIL-C-85285, FED-STD-595 color number37038, flat black. Allow to dry a minimum of 30minutes, then apply another coat.

(4) Blade tip color. Apply two coats to thetop and bottom tip surfaces. Paint in order to attaintopcoat thickness of 1 mil (25.4 μm) of polyurethanecoating (C-245) MIL-C-85285, FED-STD-595 colornumber 13538, yellow. Allow to dry a minimum of 30minutes, then apply another coat.

(5) Allow drying at room temperature for 30minutes for tack free and 8 hours for hard dry. Heatingto 90 to 120°F (32 to 48°C) for 2 hours may acceleratedrying.

n. Alternate topcoat:

(1) Upper surfaces. Apply two or threecoats (as applicable) in order to attain topcoatthickness of 1.2 to 1.5 mils (30.48 to 38.10 μm) ofacrylic lacquer MIL-L-81352, color number 27925,semigloss white. Allow to dry a minimum of 30minutes, then apply another coat.

(2) Upper surface high visibility. Apply twocoats on top of the upper surface paint in order toattain topcoat thickness of 1.2 to 1.5 mils (30.48 to38.10 μm) of acrylic lacquer MIL-L-81352, colornumber 12197, gloss orange. Allow to dry a minimumof 30 minutes, then apply another coat.

(3) Lower surface and root end closures.Apply two coats on the bottom of the lower surface.Paint in order to attain topcoat thickness of 1.2 to 1.5mils (30.48 to 38.10 μm) of acrylic lacquerMIL-L-81352, color number 37038, flat black. Allow todry a minimum of 30 minutes, then apply another coat.

(4) Blade tip color. Apply two coats to thetop and bottom tip surfaces. Paint in order to attaintopcoat thickness of 1 mil (25.4 μm) of acrylic lacquerMIL-L-81352, color number 13538, yellow. Allow to drya minimum of 30 minutes, then apply another coat.

(5) Allow drying at room temperature for 30minutes for tack free and eight hours for hard dry.Heating to 90 to 120°F (32 to 48°C) for two hours mayaccelerate drying.

BHT-407-MM-6


62-47. MAIN ROTOR BLADE — POLYURETHANEPROTECTIVE TAPE

Use of polyurethane tape is optional with individualoperator. Its use is recommended for protectionagainst abrasion of leading edge of blade in areas ofhigh sand and dust conditions. The tape affordsmedium protection against rain. It may be removedand replaced with new tape as often as necessary.

Refer to Figure 62-16 for tape size and location.

62-47A.Polyurethane Protective Tape — Cleaningand Surface Preparation

1. Dampen a clean cloth (C-516) with isopropylalcohol (C-385) and wipe the blade surface.

2. Wipe dry with a low-lint cleaning cloth (C-516)before the isopropyl alcohol (C-385) evaporates fromthe surface.

3. Mask application area with 1-inch masking tape(C-434).

4. Sand the surface in a spanwise direction onlywith 220 or 240 grit abrasive paper (C-423).

5. Thoroughly wipe with a clean cloth (C-516) andisopropyl alcohol (C-385) until there is no trace ofresidue and wipe dry with a clean cloth (C-516).

6. Apply a thin, uniform coat of adhesive promoter(C-558) to the blade surface, using the minimum

amount that will fully coat the surface. Allow to drythoroughly (5 minutes minimum).

62-47B.Polyurethane Protective Tape — WetApplication Method

1. Mix the wetting solution as follows: thoroughlymix four drops of liquid detergent (not soap) in a pint(1/2 liter) solution of 25% isopropyl alcohol (C-385)and 75% water.

2. Mark the correct position of the tape on the bladesurface (Figure 62-16).

3. Remove the liner and flood the adhesive side withwetting solution.

4. Thoroughly spray the blade surface with wettingsolution.

5. Position the erosion tape (C-557) on the bladesurface and spray wetting solution on the film surface(prevents squeegee from sticking).

6. Squeegee from the leading edge to the trailingedge of the blade using firm, overlapping strokes tosmooth out film. Dry the entire area with cloth. Workout blisters with the plastic squeegee.

7. To apply the next section of erosion tape (C-557),repeat step 3 through step 6.

8. Allow applied erosion tape (C-557) to dwellovernight (12 hours).

9. If blisters are present after the application,puncture tape at one end of the blister with a pin orneedle and press out with the squeegee or thumbtoward puncture.


MATERIALS REQUIRED

NUMBER NOMENCLATURE



C-434 Tape

C-516 Clean Cloth

C-558 Adhesive Promoter


MATERIALS REQUIRED

NUMBER NOMENCLATURE


C-557 Erosion Tape

BHT-407-MM-6

62-00-00ECCN EAR99

62-47C.Polyurethane Protective Tape — DryApplication Method

1. Remove half of the liner from the adhesive side ofthe erosion tape (C-557).

2. Align the erosion tape (C-557) and press oneedge to the blade surface with finger.

3. Squeegee from the leading edge to the trailingedge of the blade using firm overlapping strokes tosmooth out the tape.

4. Remove the remaining half of the liner and repeatstep 3.

62-47D.Polyurethane Protective Tape — Inspection

1. After each mission, when practical, inspect thetape on the leading edge of the main rotor blades. Ifany of the following conditions exist, replace the tape.

• Wear-through of tape

• Void or blistering of tape

62-47E.Polyurethane Protective Tape — EdgeSealing (Optional)

1. Prepare erosion tape (C-557) for edge sealing byapplying a strip of tape (C-434) across the top of the

erosion tape (C-557) 1/32 inch back from the edge.Apply a second strip of tape (C-434) 1/8 inch forwardof the edge of the erosion tape (C-557). This willprovide a neat, defined area for the application of theepoxy edge sealant.

2. Apply a bead of edge sealer (C-149) betweenboth strips of tape (C-434). With a fitted rubber glove,use a finger to spread and smooth the sealant beadbetween the strips of tape.

3. Allow the adhesive to partially cure,approximately 30 minutes. Remove the tape (C-434)to allow the edges of the adhesive to flow smoothly onthe surface and the erosion tape (C-557) to make atapered edge. The 30-minute cure time can beadjusted up or down depending if the ambienttemperature is higher or lower than 72°F (22°C).

62-47F. Polyurethane Protective Tape — Removal

1. Pull on tape by keeping the angle of removalperpendicular (90°) to the surface and pull at amoderate speed.

• If the angle is more or less, there is greaterchance of adhesive transferring from the tapeto the surface.

• The same problem is possible if the tape isremoved too slowly. If removed too quickly, thetape may tear or sliver.

• At 60-120°F (15-49°C), the adhesive is firmenough for clean removal without tearing orslivering.

• Removal at hotter temperature increases thepotential for adhesive transfer.

• At colder temperature, the tape is more brittlewith increased chance for slivering.

• For minor adhesive transfer, rub the adhesivewith your finger into a ball and wipe it off. Or,dab up the adhesive with another piece oftape.

• For major adhesive transfer that is tacky, usecommon cleaning agents such as 3M citrusbase cleaner, mineral spirits, or industrialsolvents. Refer to the BHT-ALL-SPM for


MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-557 Erosion Tape


MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-149 Edge Sealer

C-434 Tape

C-557 Erosion Tape

8 APR 2011 Rev. 30 Page 56A

BHT-407-MM-6

ECCN EAR9962-00-00

cleaning of the stainless steal leading edgeabrasion strip.

• For hard adhesive on hard surfaces, scrapewith a plastic/Plexiglas scraper or sand withfine grit paper. Use caution to prevent surfacedamage.

62-48. MAIN ROTOR BLADE —INSTALLATION


NUMBER NOMENCLATURE

T101626 Sling


MATERIALS REQUIRED

NUMBER NOMENCLATURE



C-561 Grease

Page 56B Rev. 34 16 FEB 2012

BHT-407-MM-6


Figure 62-16. Polyurethane Protective Tape — Installation407MM_62_0015_c02

Apply erosion tape (2) as per paragraph 62-47.

NOTES

1. Erosion strip2. Erosion tape

Chord width should be equal on both sides.

Install three segments of 20 inches (508 mm) in length by 4 inches (102 mm) wide.

2

1

2.0 IN.(51 mm)

1

1 2

2

3

20 IN.(508 mm) 20 IN.

(508 mm)

3

20 IN.(508 mm)

BHT-407-MM-6


CAUTION

THE MAIN ROTOR BLADES AND THE

MAIN ROTOR HUB ASSEMBLY

COMPONENTS ARE COLOR CODED

FOR POSITION. ALL THE COMPONENTS

OF ONE COLOR THAT ARE REMOVED

MUST BE INSTALLED IN THE SAME

COLOR LOCATION.

NOTE

The installation procedure for one main

rotor blade (3, Figure 62-7) is given. The

installation procedure for the other three

main rotor blades is the same.

Lift the blade by hand only when a hoist is

not available and only if you have two

maintenance platforms.

1. Put the sling (T101626) (4, Figure 62-7) on the

hoist. Put the hoist directly over the center of gravity of

the main rotor blade (3). Attach the sling straps around

the main rotor blade.

2. Attach a rope to the tiedown plate (5) at the end

of the main rotor blade (3). Use the rope to control the

main rotor blade during the installation.

3. Lift the main rotor blade (3) and move it in

position on the main rotor blade grip (1). Ensure that

the color code of the main rotor blade grip and main

rotor blade are the same.

4. Apply corrosion preventive compound (C-104) to

the mating surfaces of the fixed diameter blade bolts

(2) and to the mating surfaces of the expandable blade

bolts (12), if used. Apply corrosion preventive

compound (C-104) or grease (C-561) to the main rotor

blade grip (1) blade bolt bushing inside diameter and

surfaces in contact with the main rotor blade (3). Do

not apply corrosion preventive compound (C-104) or

grease (C-561) to the threads of the fixed diameter

blade bolt.

NOTE

The use of expandable blade bolts (12)instead of fixed diameter blade bolts (2) isoptional. The expandable blade bolts mayonly be installed on the trailing edge of theorange blade and the leading edge of thegreen blade, OR the trailing edge positionsof the red and blue blades. If the fixeddiameter blade bolts are used, do step 5through step 10. If an optional blade fold kitis installed, do step 11 through step 19.

Lift the main rotor blade (3) until the bladeis horizontal or slightly above horizontal toassist with installation of the fixed diameterblade bolts.

5. Align the bolt holes of the main rotor blade grip(1) and of the main rotor blade (3). Install fixeddiameter blade bolts (2) in the bolt holes.

6. Install washers (7) and nuts (8) on the fixeddiameter blade bolts (2).

7. Tighten nuts (8) and safety with cotterpins (9).

8. Remove the sling (4) from the main rotor blade(3) and remove the rope from the tiedown plate (5).

9. Apply corrosion preventive compound (C-101) toall nuts, bolts (including all visible threads), andwashers that have been installed in the main rotorblade grips (1).

10. If a new main rotor blade (3) has been installed,track the main rotor blade (Chapter 18) and do aoperational flight check.

NOTE

Step 11 through step 19 are to be followedif a blade fold kit is installed.

11. Align the bolt holes of the main rotor blade grip(1) and of the main rotor blade (3).

T

BHT-407-MM-6


NOTE

Lift the main rotor blade (3) until the bladeis horizontal or slightly above horizontal toassist with installation of the expandableblade bolts (12).

12. Put the expandable blade bolts (12) in theappropriate positions only, as follows:

• The trailing edge position of the orange bladeand the leading edge position of the greenblade

or

• The trailing edge position of the red blade andthe blue blade

13. Do a tension check of the expandable blade bolt(12) as follows:

a. Raise the bolt handle (13).

b. Using a fish scale at the end of the bolt handle(13), pull down the handle and measure the closingforce.

c. Make sure the force is 50 to 75 pounds (23 to34 kg). Otherwise, turn the adjustment nut (14) untilyou get the correct tension.

d. Record the value of the tension for theexpandable blade bolt (12).

e. Install the safety lock hair pin (15) to securethe bolt handle (13) to the expandable blade bolt (12).

14. Install the fixed diameter blade bolt (2) in theremaining position of the main rotor blade (3).

15. Install the washer (7) and the nut (8) on the fixeddiameter blade bolt (2).

16. Tighten the nut (8) and safety with the cotterpin (9).

17. Remove the sling (4) from the main rotor blade(3) and remove rope from the tiedown plate (5).

18. Apply corrosion preventive compound (C-101) toall nuts, bolts (including all visible threads), and

washers that have been installed in the main rotorblade grip (1).

19. If a new main rotor blade (3) has been installed,track the main rotor blades (Chapter 18) and do anoperational flight check.

62-49. MAIN ROTOR SYSTEM — FRAHMASSEMBLY

NOTE


The Frahm assembly (2, Figure 62-17) is installed ontop of the main rotor hub assembly (5). The Frahmreduces the natural 4/rev vibration from the main rotortransmitted to the airframe. The Frahm is constructedof a housing assembly (13, Figure 62-18), a plate (2)and a weight assembly (10) mounted on eight springs(9). The Frahm is statically tuned at the factory andrequires dynamic tuning once installed on thehelicopter. The Frahm assembly tuning isaccomplished by adding or removing weights (7) fromthe weight assembly (Chapter 18 or TB 407-99-14). Afiberglass cover (1) attached on top of the Frahmassembly reduces drag and protects the Frahm fromthe environment.

62-50. FRAHM ASSEMBLY — CONDITION ANDSECURITY — INSPECTION

1. Inspect the fiberglass cover (1, Figure 62-18) forsecurity, cracks, and delamination.

2. Inspect the visible portion of the plate (2) forgeneral condition and security. Pay particular attentionfor cracks in the fiberglass cover (1) attachment lugareas.

3. Inspect the housing assembly (13) for generalcondition and security. Pay particular attention in theattachment lug areas for cracks.

62-51. FRAHM ASSEMBLY — REMOVAL

NOTE

For flight operations with the Frahmdamper and cover removed, refer toTB 407-03-51.

T

BHT-407-MM-6


Figure 62-17. Frahm Assembly — Removal and Installation407MM_62_0016_c02

3

4

6

CORROSION PREVENTIVE COMPOUND (C-101)50 TO 70 IN-LBS(5.6 TO 7.9 Nm)

75 TO 95 IN-LBS(8.5 TO 10.7 Nm)

1

Apply a coating of corrosion preventive compound (C-101) to all bolt heads,washers, nuts and exposed threads after installation.

1

NOTES

2

1. Cover2. Frahm assembly3. Nut4. Washer5. Main rotor hub assembly6. Screw

1

2

1

1

1

2

5

If necessary, omit the washers (4) to correctly engage the nuts (3).2

2

1

BHT-407-MM-6


Figure 62-18. Frahm Assembly and Workaids (Sheet 1 of 2)407MM_62_0017_c01

14. Retaining plate15. Bolt

2. Plate

16. Washer

13. Housing assembly12. Plug11. Stud10. Weight assembly9. Spring8. Pad assembly7. Weights6. Washer5. Nut4. Washer3. Bolt

1. Fiberglass cover

18

19

21

17

13

14

16

15

3

6

5

2

11

20

(6.78 TO 9.04 Nm)60 TO 80 IN-LBS

12

10

17. Stop assembly

20. Bushing19. Washer18. Bolt

9

87

1

21. Spring seat

4

22. Nutplate

22

ASEE DETAIL

Seat groove of spring seats (21)(straight portion) as shown forappropriate positioning/lockingof springs (9).

23. Rubber pad 23

1

ADETAIL

10

21

1

NOTE

TYPICAL FOUR LOCATIONS ONWEIGHT ASSEMBLY (10)

BHT-407-MM-6


Figure 62-18. Frahm Assembly and Workaids (Sheet 2 of 2)407MM_62_0051_c01

ITEM 1

ITEM 2

ITEM 3

ITEM 4

THREADED ROD USED TO REMOVE AND INSTALL SPRING (9, FIGURE 62-18).

1. 0.250 inch (6.35 mm) diameter 20 UNJC threads 9.000 inch (228.60 mm) long threaded rod2. Washer AN970-5

4. Nuts (two) locked together (diameter 20 UNJC threads) 3. Nut (0.250 inch (6.35 mm) diameter 20 UNJC threads

PRESSING PLUG USED TO REMOVE AND INSTALL PAD ASSEMBLY (8, FIGURE 62-18) ANDTO INSTALL STOP ASSEMBLY (17) IN HOUSING ASSEMBLY (13).

(115.07 TO 115.57 mm)4.530 TO 4.550 IN.

MATERIAL: ALUMINUM

(6.10 TO 6.60 mm) 0.240 TO 0.260 IN.

PRESSING PLUG USED TO REMOVE AND INSTALL PLUG (12, FIGURE 62-18) INRETAINING PLATE (14) AND TO INSTALL SEAT (21) IN WEIGHT ASSEMBLY (10).

MATERIAL: ALUMINUM

PRESSING SLEEVE USED TO INSTALL BEARING ASSEMBLY (7, FIGURE 62-20) ON HOUSING (8).

MATERIAL: ALUMINUM

1 2 3 4

1.00 IN.(25.40 mm)

O.D.3.160 IN.

(80.26 mm)

I.D.3.005 IN.

(76.33 mm)

0.97 TO 1.03 IN.(24.7 TO 26.1 mm)

0.97 TO 1.03 IN.(24.7 TO 26.1 mm)

BHT-407-MM-6


1. Put a stable maintenance platform beside thehelicopter near the transmission.

NOTE

Ensure the fiberglass cover has an indexmark for reinstallation at same location.

2. Using a TORQ-SET screwdriver bit 170-1/4B,remove the screws (6, Figure 62-17) that attach thecover (1) to the Frahm assembly (2). Remove thecover.

3. Remove the nuts (3) and the washers (4).

4. Lift the Frahm assembly (2) off the main rotor hubassembly (5).

62-52. FRAHM ASSEMBLY — CLEANING

1. Wipe the cover (1, Figure 62-17) with a clothdampened with aliphatic naphtha (C-305) ordrycleaning solvent (C-304).

2. Clean the cover (1) with a mild solution ofcleaning compound (C-318) and water. Rinse thecover with clean water and dry with a clean cloth.

CAUTION

DO NOT USE SILICONE TYPE WAXES.S IL ICONE WAXES CAN CAUSEPROBLEMS WITH FUTURE REPAIRS.

3. Apply a layer of wax (C-412) to the cover (1).

4. Wipe the Frahm assembly (2) with a clothdampened with aliphatic naphtha (C-305) ordrycleaning solvent (C-304).

62-53. FRAHM ASSEMBLY — DISASSEMBLY

WARNING

SPRINGS (13, FIGURE 62-19) AREUNDER PRESSURE AND CANCAUSE INJURY IF D ISASSEMBLYPROCEDURES ARE NOT FOLLOWED.


NUMBER NOMENCLATURE

170-1/4B Bit (TORQ-SET)


MATERIALS REQUIRED

NUMBER NOMENCLATURE




C-412 Wax


NUMBER NOMENCLATURE

Item 1 (Qty 4) Workaid (Figure 62-18, Sheet 2)

Item 2 Workaid (Figure 62-18, Sheet 2)


NOTES:

Used to remove and install the spring (13,Figure 62-19).

Used to remove and install the padassembly (8, Figure 62-18).

Used to remove and install the plug (12,Figure 62-19).

1

2

3

1

2

3

BHT-407-MM-6

62-00-00Page 64 Rev. 23 7 NOV 2006

Figure 62-19. Frahm Assembly Springs — Removal and Installation407MM_62_0019

14. Spring seat

2. Plate

13. Spring12. Plug11. Retaining plate10. Washer9. Nut8. Nuts (two)7. Threaded rod workaid (Item 1 Fig. 62-18, Sheet 2)6. Washer5. Bolt4. Bolt3. Washer

1. Housing assembly

2

(6.78 TO 9.04 Nm)60 TO 80 IN-LBS

1312

1

15

43

11

5

6

107

98

89

710

43

43

14

D

BC

A

15. Weight assembly

Eight threads in weight assembly (15) for installation of threaded rod workaids (7).

Plate (2) removed for clarity. Diametrically opposed spring pairs (A) and (B) or (C) and (D)must be removed/installed at the same time.

NOTES

2

2 2 21

22

2

1

2

CORROSION PREVENTIVE COMPOUND (C-104) 3

3

CORROSION PREVENTIVE COMPOUND (C-101)2

1

4

4 Apply a coating of corrosion preventive compound (C-101) to all bolt heads, washers, nuts and exposed threads after installation.

Apply a coating of corrosion preventive compound (C-104) to all bolt shanks prior to installation. Do not apply corrosion preventive compound to bolt threads.

BHT-407-MM-6


CAUTION

THE PLATE (2, FIGURE 62-19) MUST BEINSTALLED FOR SPRING (13) REMOVALAND INSTALLATION. IF THE PLATE ISNOT INSTALLED, DAMAGE TO THEHOUSING ASSEMBLY (1) CAN OCCUR.

NOTE

If the same parts are to be reinstalled, indexto ensure reinstallation at the samelocation.

The springs (13, Figure 62-19) must bereplaced in pairs. All springs and springseats (14) on the Frahm assembly must beof the same respective part number. Referto Table 62-2 for Frahm assemblyconfiguration.

Springs (13) must be simultaneouslyremoved in pairs on diametrically opposedsides.

1. Remove safety wire from the bolts (4,Figure 62-19).

2. Install four threaded rods (7) (Ref: Workaid Item1, Figure 62-18, Sheet 2) in the two diametricallyopposed pairs of threads in the weight assembly (15,Figure 62-19). Screw the threaded rods until thethreads are flush with the inside surface of the weightassembly.

3. Hold the threaded rod (7) outboard nuts (8) andtighten the inboard nut (9) fingertight until the washer(10) contacts the retaining plate (11).

4. Remove the retaining plate (11) attaching bolts(4) and washers (3).

5. Hold the threaded rod (7) outboard nuts (8) andevenly loosen the 4 inboard nuts (9) to equally relievethe tension on the two opposed pairs of springs (13).

6. When the spring tension is completely released,remove the four threaded rods (7), retaining plates(11) with plugs (12), and springs (13).

7. Using a suitable arbor press and pressing plug(Workaid Item 3, Figure 62-18, Sheet 2), remove theplug (12, Figure 62-19) from the retaining plate (11).

8. Repeat step 2 through step 7 for the fourremaining diametrically opposed springs (13).

9. Remove safety wire; remove the bolts (5) and thewashers (6).

10. Remove the plate (2) from the housingassembly (1).

11. Remove the weight assembly (10, Figure 62-18)from the housing assembly (13).

12. Remove the spring seat (21) from the weightassembly (10) as follows:

CAUTION

DO NOT EXCEED 200°F (93.3°C).

a. Apply heat to the weight assembly (10).

b. Use a plastic hammer and tap on thecircumference of the spring seat to break it loose in theweight assembly (10).

c. Apply protection to the jaws of the water pumppliers or use electrical connector pliers and remove thespring seat (21).

13. Remove the nuts (5), washers (6), and weights(7). Record the amount of weights removed to ensuresame weights are reinstalled.

14. Using a suitable arbor press and pressing plug(Workaid Item 2, Figure 62-18, Sheet 2), remove thepad assembly (8, Figure 62-18) from the weightassembly (10).

15. Remove safety wire from the bolts (18). Removethe bolts and the washers (19).

BHT-407-MM-6

62-00-00Page 66 Rev. 23 7 NOV 2006

Figure 62-20. Frahm Stop Assembly407MM_62_0020

2. Nut

9. Shim8. Adapter7. Bearing and liner assembly6. Bolt5. Washer4. Retaining plate3. Washer

1. Safety pin

4

3

8

(3.4 TO 4.5 Nm)30 TO 40 IN-LBS

6

5

2

9

1

MEASURE GAP AT FOUR LOCATIONSUSING FEELER GAUGE

7

10

10. Stop assembly

CORROSION PREVENTIVE COMPOUND (C-104) 1

2


1

2

1


Apply a coating of corrosion preventive compound (C-104) to all bolt shanks prior to installation. Do not apply corrosion preventive compound to bolt threads.

NOTES

BHT-407-MM-6


CAUTION


16. Apply heat to the housing assembly (13) toremove the stop assembly (17).

17. Using a hammer and a wooden punch, gently tapthe stop assembly (17) out of the housingassembly (13).

18. Disassemble the stop assembly (10,Figure 62-20) as follows:

a. Remove the safety pin (1), nut (2), washer (3),retaining plate (4), washer (5), and bolt (6).

b. Remove the shim (9).

NOTE

If the bearing and liner assembly (7) isremoved from the adapter (8), it should bereplaced with a new bearing and linerassembly (7).

c. Apply heat to the adapter (8) and, using asuitable jaw puller, remove the bearing and linerassembly (7) from the adapter (8).

62-54. FRAHM ASSEMBLY — INSPECTION

1. Inspect the fiberglass cover (1, Figure 62-18) forcracks and delamination.

2. Inspect the plate (2) for general condition. Payparticular attention in the fiberglass cover (1)attachment lugs area for cracks. Inspect the rubberpads for wear, tear, and debonding. Refer toFigure 62-21 for damage and repair limits.

3. Inspect the pad assembly (8, Figure 62-18) forgeneral condition. Inspect the rubber bumper for wear,tear, and debonding. Refer to Figure 62-22 fordamage and repair limits.

4. Inspect the springs (9, Figure 62-18) formechanical damage, corrosion, and cracks. Refer toFigure 62-23 for damage and repair limits.

5. Inspect the plug (12, Figure 62-18) for wear andcracks. Refer to Figure 62-24 for damage and repairlimits.

6. Inspect the weight assembly (10, Figure 62-18)for general condition. Refer to Figure 62-25 fordamage and repair limits.

7. Inspect the studs (11, Figure 62-18) forlooseness. Inspect the threads for condition.

8. Inspect the spring seats (21) for cracks, wear,and looseness. Refer to Figure 62-26 for damage andrepair limits.

9. Inspect the housing assembly (13, Figure 62-18)for general condition. Pay particular attention in theattachment lug areas for cracks. Inspect the bushings(20) for looseness and damage. Inspect the rubberpads for wear, tears, and debonding. Refer toFigure 62-27 for damage and repair limits.

10. Inspect the retaining plates (14, Figure 62-18) forgeneral condition, cracks, and deformation. Payparticular attention in the areas surrounding themounting holes. Refer to Figure 62-28 for damage andrepair limits.

11. Inspect the stop assembly (17, Figure 62-18) asfollows:

a. Inspect the bearing and liner assembly (7,Figure 62-20) for general condition and roughness ofthe bearing. If the bearing is rough or the liner is loose,replace the bearing and liner assembly.

b. Inspect the retaining plate (4) for generalcondition. Refer to Figure 62-29 for damage and repairlimits.

c. Inspect the adapter (8, Figure 62-20) forgeneral condition. Pay particular attention in theattachment lugs area for cracks. Refer to Figure 62-30for damage and repair limits.

BHT-407-MM-6

62-00-00Page 68 Rev. 23 7 NOV 2006

Figure 62-21. Upper Plate — Wear, Damage, and Repair Limits (Sheet 1 of 2)407MM_62_0052

HAVE EQUIVALENT ZONESUPPER AND LOWER SURFACES

TYPE OF DAMAGE MAXIMUM DAMAGE AND REPAIR DEPTH

0.030 inch(0.762 mm)

0.015 inch(0.381 mm)

0.030 inch(0.762 mm)

Not critical

Not critical

0.030 inch(0.762 mm) X45°

0.015 inch(0.381 mm) X45°

0.030 inch(0.762 mm) X45°

Not critical

0.010 inch(0.254 mm)

0.005 inch(0.127 mm)

0.010 inch(0.254 mm)

0.100 square inch(64.5 mm²)

One per lug

0.030 inch(0.762 mm) X45°

0.015 inch(0.381 mm) X45°

0.030 inch(0.762 mm) X45°

Not critical

DAMAGE LOCATION SYMBOLSUPPER PLATE (407-010-158)MATERIAL: ALUMINUM ALLOY

Mechanical before and after repair

Corrosion before repair

Corrosion after repair

Maximum area per full depth repair

Number of repairs

Mechanical edge chamfer damage before and after repair

Corrosion edge chamfer damage before repair

Corrosion edge chamfer damage after repair

Number of edge chamfer damage

5

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 69

Figure 62-21. Upper Plate — Wear, Damage, and Repair Limits (Sheet 2 of 2)407MM_62_0053

No cracks permitted.

No looseness of nut plate permitted.

No looseness of dowel pin permitted.

No debonding or damage through rubber pad permitted.

One full depth repair permitted at any local area.

NOTES

1.

2.

3.

4.

5

BHT-407-MM-6


Figure 62-22. Pad Assembly — Wear, Damage, and Repair Limits407MM_62_0054_c01

0.010 inch(0.254 mm)

0.010 inch(0.254 mm)

One per surface per 1/4 circumference

0.040 inch(1.02 mm) X45°

0.040 inch(1.02 mm) X45°

Not critical

No debonding permittedNo damage or wear through rubber permitted

Mechanical before andafter repair

Corrosion before andafter repair


Number of repairs

Mechanical edgechamfer damagebefore and afterrepair

Corrosion edgechamfer damagebefore and afterrepair

Number of edgechamfer damage

Rubber bumper

RUBBER BUMPER

407-010-171 407-310-107


NOTE


DAMAGE LOCATION SYMBOLSPAD ASSEMBLY (407-010-171/407-310-107)MATERIAL: CRES STEEL

0.50 square inch(322.6 sq. mm²)

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 71

Figure 62-23. Spring — Wear, Damage, and Repair Limits407MM_62_0056


Corrosion beforeand after repair


Number of repairs

0.001 inch

(0.0254 mm)

0.001 inch

(0.0254 mm)

Not critical

Not critical


NOTE


DAMAGE LOCATION SYMBOLS

SPRING (407-310-104)

MATERIAL: CRES STEEL

BHT-407-MM-6


Figure 62-24. Plug — Wear, Damage, and Repair Limits407_MM_62_0057_c01


NOTE



PLUG (407-010-155)

MATERIAL: PLASTIC

C

ADIA.

BDIA.

C

-109-107



Number of repairs

Wear damagedimensional limits

Mechanical edge chamferdamage before andafter repair


0.015 inch(0.381 mm)

1/4 circumference

One per surface

-107

Diameter A: 1.365 inch(34.67 mm) minimum

Diameter B: 1.050 inch(26.67 mm) minimum

C: 0.155 inch(3.937 mm) minimum

Not critical

-109

Diameter A: 1.340 inch(34.04 mm) minimum

Diameter B: 1.050 inch(26.67 mm) minimum

C: 0.155 inch(3.937 mm) minimum

0.030 inch

(0.762 mm) X

45°

ADIA.

BDIA.

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 73

Figure 62-25. Weight Assembly — Wear, Damage, and Repair Limits (Sheet 1 of 2)407_MM_62_0058

0.010 inch

(0.254 mm)

0.010 inch

(0.254 mm)

1/4 circumference

One per surface

Not critical

0.010 inch

(0.254 mm)

1/4 circumference

0.030 inch

(0.762 mm)

0.030 inch

(0.762 mm)

Two per surface

Not critical




Number of repairs


Corrosion edgechamfer damagebefore and afterrepair


Spring seat andstop boresmechanical damagebefore and afterrepair

SPRING SEATS 407-010-173

AND STOP 407-310-107 NOT

SHOWN FOR CLARITY



WEIGHT ASSEMBLY (407-010-151)


DIA. A

DIA. C

DIA. B

0.030 inch

(0.762 mm) X

45°

0.060 inch

(1.524 mm) X

45°

0.030 inch

(0.762 mm) X

45°

0.060 inch

(1.524 mm) X

45°

0.50 square inch

(322.6 mm²)

BHT-407-MM-6

62-00-00Page 74 Rev. 23 7 NOV 2006

Figure 62-25. Weight Assembly — Wear, Damage, and Repair Limits (Sheet 2 of 2)407_MM_62_0059

0.010 inch

(0.254 mm)

1/4 circumference

One per bore

Diameter 'A' 0.7505

inch (19.062 mm)

maximum

Diameter 'B' 2.750

inch (69.850 mm)

maximum

Diameter 'C' 4.5415

inch (115.354 mm)

maximum

1/3 of thread

0.030 inch

(0.762 mm)

One per thread

Two threads maximum

1/3 of thread

0.030 inch

(0.762 mm)

One per thread

Two threads maximum

Spring seat and

stop bores

corrosion damage

before and after

repair

Number of bore damage

Mechanical thread damage

before and after repair

Depth

Length

Number

Corrosion thread damage

before and after repair

Depth

Length

Number

Wear limits


No looseness of stud allowed.

1.

2.

NOTES



BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 75

Figure 62-26. Seat — Wear, Damage, and Repair Limits407_MM_62_0060



SPRING SEAT (407-010-173)

MATERIAL: PLASTIC



Number of repairs



Wear/abrasiondepth

0.015 inch

(0.381 mm)

1/4 circumference

One per surface

0.030 inch

(0.762 mm) X

45°

Not critical

A: 0.185 inch

(4.699 mm) minimum

at Point A

B: 0.370 inch

(9.398 mm) maximum

Diameter C: 0.7505 inch

(19.062 mm) minimum


NOTE

AB

DIA. C

POINT APOINT A

BHT-407-MM-6

62-00-00Page 76 Rev. 23 7 NOV 2006

Figure 62-27. Housing — Wear, Damage, and Repair Limits (Sheet 1 of 2)407MM_62_0061

Mechanical before and

after repair

Corrosion before

repair

Corrosion after

repair

Maximum area per

full depth repair

Number of repairs

Mechanical edge

chamfer damage

before and after

repair

Corrosion edge

chamfer damage

before repair

Corrosion edge

chamfer damage

after repair

Number of edge

chamfer damage

0.010 inch

(0.254 mm)

0.005 inch

(0.127 mm)

0.010 inch

(0.254 mm)

One per bore

0.030 inch

(0.762 mm) X

45°

0.015 inch

(0.381 mm) X

45°

0.030 inch

(0.762 mm) X

45°

Not critical

0.030 inch

(0.762 mm)

0.015 inch

(0.381 mm)

0.030 inch

(0.762 mm)

1.0 square inch

Two places per surface

0.030 inch

(0.762 mm) X

45°

0.015 inch

(0.381 mm) X

45°

0.030 inch

(0.762 mm) X

45°

Not critical

0.010 inch

(0.254 mm)

0.005 inch

(0.127 mm)

0.010 inch

(0.254 mm)

0.10 square inch

(64.5 mm²)

One per surface

0.030 inch

(0.762 mm) X

45°

0.015 inch

(0.381 mm) X

45°

0.030 inch

(0.762 mm) X

45°

Not critical

SPRING INSERTION

BORE MAXIMUM

DIAMETER AFTER REPAIR

2.150 IN. (54.61 mm)

MAXIMUM HOUSING

BUSHING BORE DIAMETER

0.534 IN. (13.56 mm)

407-010-154-103 BUSHING NOT SHOWN FOR CLARITY.

MAXIMUM BUSHING INSIDE DIAMETER 0.404 IN. (10.26 mm).

REFER TO TB 407-05-70.



HOUSING (407-010-152-105/-109)

MATERIAL: ALUMINUM ALLOY

3

2

3

(645.2 mm²)

0.25 square inch

(161.29 mm²)

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 77

Figure 62-27. Housing — Wear, Damage, and Repair Limits (Sheet 2 of 2)407MM_62_0062



3

Mechanical bore

damage before

and after repair

Corrosion bore

damage before repair

Corrosion bore

damage after repair


Mechanical thread

damage before

and after repair

Depth

Length

Number

Corrosion thread

damage before repair

Depth

Length

Number

Corrosion thread

damage after repair

Depth

Length

Number

0.002 inch

(0.051 mm)

1/4 circumference

0.001 inch

(0.025 mm)

1/4 circumference

0.002 inch

(0.051 mm)

1/4 circumference

One per bore

1/3 of thread

0.030 inch (0.762 mm)

One per thread

Two threads maximum

1/3 of thread

0.015 inch (0.381 mm)

One per thread

Two threads maximum

1/3 of thread

0.030 inch (0.762 mm)

One per thread

Two threads maximum

1.

Also applies to lower surface of housing.

No debonding or damage through rubber pad permitted. Replace rubber pad if damaged or

No deformation or cracks permitted.

NOTES

debonded. Use for damage and repair limits of surface under rubber pad.

2

3

BHT-407-MM-6

62-00-00Page 78 Rev. 23 7 NOV 2006

Figure 62-28. Retaining Plate — Wear, Damage, and Repair Limits (Sheet 1 of 2)407MM_62_0064



RETAINING PLATE (407-010-156-107)





Number of repairs


Corrosion edgechamfer damagebefore and after repair


0.004 inch

(0.102 mm)

0.004 inch

(0.102 mm)

0.10 square inch

(64.5 mm²)

Four per flat surface

No closer than 0.30 inch

(7.62 mm) apart

0.030 inch

(0.762 mm) X

45° around bores

0.060 inch

(1.524 mm) X

45° outer edges

0.030 inch

(0.762 mm) X

45° around bores

0.060 inch

(1.524 mm) X

45° outer edges

Not critical

407-010-155 PLUG NOT SHOWN

FOR CLARITY. SEE NOTE 3.

MAXIMUM BORE DIAMETER

0.278 IN. (7.06 mm)MAXIMUM BORE DIAMETER

1.050 IN. (26.67 mm)

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 79

Figure 62-28. Retaining Plate — Wear, Damage, and Repair Limits (Sheet 2 of 2)407MM_62_0065



Mechanical bore

damage before

and after repair

Corrosion bore

damage before

and after repair

Number of bore

damage

0.001 inch

(0.0254 mm)

1/4 circumference

0.001 inch

(0.0254 mm)

1/4 circumference

One per bore

2.

1.

For plug damage limits refer to Figure 62-24.

No deformation permitted.


NOTES

3.

BHT-407-MM-6

62-00-00Page 80 Rev. 23 7 NOV 2006

Figure 62-29. Stop Assembly Retaining Plate — Wear, Damage, and Repair Limits407MM_62_0066



PLATE (407-010-167)


0.010 inch(0.254 mm)

0.005 inch(0.127 mm)

0.010 inch(0.254 mm)

1.0 square inch

One per surface

0.030 inch(0.762 mm) X45°

0.015 inch(0.381 mm) X45°

0.030 inch(0.762 mm) X45°

Not critical

0.002 inch(0.051 mm) for1/4 circumference

0.030 inch(0.762 mm)

0.015 inch(0.381 mm)

0.030 inch(0.762 mm)

Not critical

Not critical

0.030 inch(0.762 mm) X45°

0.015 inch(0.381 mm) X45°

0.030 inch(0.762 mm) X45°

Not critical


Corrosion beforerepair

Corrosionafter repair


Number of repairs


Corrosion edgechamfer damagebefore repair

Corrosion edgechamfer damageafter repair


Bore damage


NOTE

(645.2 mm²)

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 81

Figure 62-30. Stop Assembly Adapter — Wear, Damage, and Repair Limits (Sheet 1 of 2)407MM_62-0067



STOP ASSEMBLY ADAPTER (407-010-170)


0.010 inch(0.254 mm)

0.005 inch(0.127 mm)

0.010 inch(0.254 mm)

0.50 square inch

One per quadrantper surfaceOne per lug

0.030 inch(0.762 mm) X45°

0.015 inch(0.381 mm) X45°

0.030 inch(0.762 mm) X45°

Not critical

0.002 inch(0.051 mm)

0.001 inch(0.0254 mm)

0.002 inch(0.051 mm)

0.10 square inch

One per quadrant


Corrosion beforerepair

Corrosionafter repair


Number of repairs


Corrosion edgechamfer damagebefore repair

Corrosion edgechamfer damageafter repair


(322.6 mm²) (64.5 mm²)


0.283 IN. (7.2 mm)


0.208 IN. (5.3 mm)

BHT-407-MM-6

62-00-00Page 82 Rev. 23 7 NOV 2006

Figure 62-30. Stop Assembly Adapter — Wear, Damage, and Repair Limits (Sheet 2 of 2)407MM_62-0068



Mechanical bore

damage before

and after repair

Corrosion bore

damage before

repair

Corrosion bore

damage after

repair

Number of bore

damage

0.002 inch

(0.051 mm)

1/4 circumference

0.001 inch

(0.025 mm)

1/4 circumference

0.002 inch

(0.051 mm)

1/4 circumference

One per bore


NOTE

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 83

62-55. FRAHM ASSEMBLY — REPAIR

CAUTION

THE THERMAL F IT OF PARTSPROCEDURE USING LIQUID NITROGENOR A MIXTURE OF DRY ICE ANDDENATURED ALCOHOL IS TO BE USEDONLY FOR THE PARTS SPECIFIED INTHIS PARAGRAPH.

NOTE

The following repairs are the only fieldrepairs authorized on the Frahm assembly.If other repairs are required, send theFrahm assembly to Bell HelicopterCustomer Property Return.

Only use epoxy polyamide primer (C-204)for wet installations.

Information on Frahm configurations andupgrades may be found in Table 62-1 andTable 62-2.


MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-100 Chemical Film Material



C-301 Adhesive


C-306 Toluene

C-309 MEK

C-347 Xylene

C-352 Retaining Compound

C-407 Abrasive Pad


Table 62-1. Frahm Production Effectivity

FRAHM ASSEMBLY NOTES PRODUCTION EFFECTIVITY

407-010-150-103 53000 through 53199

407-010-150-105 53200 through 53464

407-010-150-109 53465 through 53655(except 53639)

407-010-150-111 53639, 53656 through subsequent

NOTES:

The Frahm assembly 407-010-150-103 is not field repairable and cannot be upgraded to a later configuration.

The Frahm assembly 407-010-150-105 is field repairable, but it must be upgraded to the -109 or -111 configuration if a spring or a spring seat requires replacement. The upgrade can be performed using the information given in Table 62-2 and in TB 407-05-70.

1

2

3

4

1

2

BHT-407-MM-6


Table 62-1. Frahm Production Effectivity (Cont)

NOTES (CONT):

The Frahm assembly 407-010-150-109 is field repairable. The -109 Frahm assembly can be upgraded to the -111 configuration using the information given in TB 407-05-70.

The Frahm assembly 407-010-150-111 is field repairable. The -111 Frahm assembly is the latest production configuration that can be used on all Model 407 helicopters.

3

4

Table 62-2. Frahm Assembly Configurations

NOMENCLATURE QUANTITY PART NUMBER NOTES FRAHM ASSEMBLY

Frahm assembly 407-010-150 -105

-109 -111

Housing assembly (1) 407-010-152-105 X X

407-010-152-109 X

Top plate assembly

(1) 407-010-158-105 X X X

Weight (1) 407-010-151-107 X X X

Spring seat (8) 407-010-173-101

X

407-010-173-103

X

407-010-173-105 X X

Pad assembly (1) 407-310-107-101 X X X

Spring (8) 407-310-104-103 X

407-310-104-105

X X

Retaining plate (4) 407-010-156-107 X X X

Plug (8) 407-010-155-109 X X X

Stop assembly (1) 407-010-165-103 X X X

NOTES:

Replaced by Frahm assembly 407-010-150-109.

Can be upgraded to the -109 configuration. When the upgrade is accomplished, the Frahm assembly is to be reidentified as 407-010-150-105-109FM with a vibrating stylus.

Replaced by Frahm assembly 407-010-150-111. Can be upgraded to the latest configuration (refer toTB 407-05-70).

1 2 3 3 9

1010

4 5

5 6

7

5

7 8

1

2

3

BHT-407-MM-6


1. Repair damage on the plate (2, Figure 62-18) asfollows:

a. Blend smooth mechanical and corrosiondamage using 220 grit abrasive cloth or paper(C-423). Do not exceed damage limits in Figure 62-21.

b. Chemically treat bare metal surface withchemical film material (C-100).

c. Prime using epoxy polyamide primer (C-204)and paint touch up with polyurethane coating (C-245),FED-STD-595 color code 36440 (light gull grey) or16440 (gloss grey).

d. Replace loose or damaged nutplate (22,Figure 62-18).

2. Repair the weight assembly (10) as follows:


b. Brush cadmium plate repaired area(BHT-ALL-SPM). If brush cadmium plate equipment isnot available, prime bare metal surface using epoxypolyamide primer (C-204).

CAUTION

DO NOT EXCEED 200°F (93.3°C) IF THEPAD ASSEMBLY (8, FIGURE 62-18) ISINSTALLED IN THE WEIGHT ASSEMBLY(10). IF THE PAD ASSEMBLY IS NOTINSTALLED, HEAT UP TO 400°F MAY BEAPPLIED.

c. To replace a loose or damaged stud (11,Figure 62-18), apply heat to the weight assembly (10)and remove the damaged stud.

d. Install the stud (11) with retaining compound(C-352). The exposed portion of the stud must bebetween 1.95 and 2.01 inches (49.53 and 51.05 mm)after installation (without pad assembly (8) installed).

3. Polish out mechanical or corrosion damage onthe spring (9) as follows:

a. Polish out surface corrosion with abrasive pad(C-407). Do not exceed damage limits in Figure 62-23.

b. Apply epoxy polyamide primer (C-204) to baremetal surface.

4. Repair mechanical and corrosion damage on thehousing assembly (13, Figure 62-18) as follows:


Table 62-2. Frahm Assembly Configurations (Cont)

NOTES (CONT):

Spring seat 407-010-173-101 was used on helicopters 53200 through 53259.

Not procurable. If seat 407-010-173-101/-103 or spring 407-310-104-103 requires replacement, all seats and springs must be replaced with seats 407-010-173-105 and springs 407-310-104-105.

Spring seat 407-010-173-103 was used on helicopters 53260 through 53464.

Spring seat 407-010-173-105 must be used with spring 407-310-104-105.

If a spring replacement is required, its adjacent spring must also be replaced (springs must be replaced in pairs). All springs and spring seats on the Frahm assembly must be of the same part number.

Replaces Frahm assembly 407-010-150-105 and -109. Can be used on all Model 407 helicopters.

The 407-010-152-109 housing assembly is identical to the -105 except the 407-010-154-103 bushing inside diameter is reamed to a new dimension (refer to TB 407-05-70).

4

5

6

7

8

9

1010

BHT-407-MM-6

62-00-00Page 86 Rev. 23 7 NOV 2006


c. Apply epoxy polyamide primer (C-204) torepaired area.

d. Paint touch-up with polyurethane coating(C-245), FED-STD-595 color code 36440 (light gullgrey) or 16440 (gloss grey).

5. Replace damaged bushing (20, Figure 62-18) inhousing assembly (13) as follows:

CAUTION


a. Apply heat to housing assembly (13) lug.

CAUTION

ENSURE LUG IS ADEQUATELYSUPPORTED DURING THE REMOVALOF THE BUSHING (20).

b. Using a suitable pressing plug, press bushing(20) out of housing assembly (13) lug.

c. Clean primer residue from lug bore.

CAUTION


THE BUSHING (20) IS TO BE THERMALFITTED IN THE HOUSING ASSEMBLY(13). COLD INSTALLATION OF THEBUSHING IN THE HOUSING ASSEMBLYMAY DAMAGE THE HOUSINGASSEMBLY.

NOTE

Proper heating of the housing assembly(13) and cooling of the bushing (20) shouldpermit hand installation of the bushing inthe housing assembly.

d. Apply heat to housing assembly (13) lug.

e. Cool the bushing (20) using liquid nitrogen ora mixture of dry ice and denatured alcohol.

f. Apply epoxy polyamide primer (C-204) tomating surfaces of lug bore and bushing (20).

g. While the primer is wet and the parts are atrequired thermal conditions, install bushing (20) in thehousing assembly (13) with hand pressure only. Ifrequired, the bushing (20) may be gently tapped with asoft mallet using caution to prevent cocking of thebushing (20) in the bore.

h. After the housing assembly (13) and thebushing (20) have returned to room temperature, lineream bushing (20) to 0.400 to 0.404 inch (10.16 to10.26 mm).

6. Replace damaged rubber pad (23) as follows:

a. Taking care not to damage housing assembly(13), remove rubber pad (23). Ensure that anyremaining adhesive is removed from surface ofhousing (14).

b. Inspect surface of housing assembly (13)where rubber pad (23) was bonded per Figure 62-27.

c. If primer was removed from surface ofhousing assembly (13) during removal of rubber pad(23) and associated adhesive, lightly abrade with 220grit abrasive cloth or paper (C-423). Do not exceeddamage limits in Figure 62-27.

d. Clean surface with aliphatic naphtha (C-305)and apply a light coat of epoxy polyamide primer(C-204).

e. Lightly abrade dry primed surface (not toremove primer) with 400 grit abrasive cloth or paper(C-423). Clean surface with clean cloth and aliphaticnaphtha (C-305).

f. Prepare the area of the new rubber pad (23,Figure 62-18) to be bonded, by abrading with 80 gritabrasive cloth or paper (C-423). Clean surface with acloth wetted with toluene (C-306) or xylene (C-347).Wipe surface dry with clean cloth.

g. Mix adhesive (C-301) and apply to preparedsurfaces of rubber pad (23) and housing assembly

BHT-407-MM-6


(13). Maximum strength is obtained with a bond linethickness of 10 mils.

h. Apply the rubber pad (23) to the housingassembly (13).

i. Apply firm contact pressure of 5 to 20 PSI(34.5 to 138 kPa) during cure. Cure at 70 to 80° F (21to 26.6° C) for 2 days. An accelerated cure may beachieved at 160° F (71.0° C) for 2 hours.

7. Repair mechanical and corrosion damage on theretaining plate (14) as follows:


b. Apply a light coat of epoxy polyamide primer(C-204) to the repaired area.

c. Paint touch-up with polyurethane coating(C-245), FED-STD-595 color code 36440 (light gullgrey) or 16440 (gloss grey).

8. Repair the stop assembly adapter (8,Figure 62-20) as follows:



c. Apply a light coat of epoxy polyamide primer(C-204) to repaired area.


9. Repair mechanical and corrosion damage on theretaining plate (4, Figure 62-20) as follows:



c. Apply a light coat of epoxy polyamide primer(C-204) to the repaired area.


62-56. FRAHM ASSEMBLY — ASSEMBLY


NUMBER NOMENCLATURE

Item 1 (Qty 4) Workaid (Figure 62-18, Sheet 2)




NOTES:

Used to remove and install the spring (13,Figure 62-19).

Used to remove and install the padassembly (8, Figure 62-18) and install the stop assembly (17) in the housingassembly (13).

Used to remove and install the plug (12,Figure 62-19) in the retaining plate (11) and to install the spring seat (21,Figure 62-18) in the weight assembly (10).

Used to install the bearing and liner assembly 7, Figure 62-20) on theadapter (8).

1

2

3

4

1

2

3

4

BHT-407-MM-6

62-00-00Page 88 Rev. 23 7 NOV 2006

WARNING

SPRINGS (13, FIGURE 62-19) AREUNDER PRESSURE AND CAN CAUSEINJURY IF ASSEMBLY PROCEDURESARE NOT FOLLOWED.

CAUTION

PLATE (2, FIGURE 62-19) MUST BEINSTALLED ON HOUSING ASSEMBLY (1)FOR SPRING (13 ) REMOVAL ANDINSTALLAT ION. IF PLATE IS NOTINSTALLED, DAMAGE TO HOUSINGASSEMBLY CAN OCCUR.

NOTE

If same parts previously removed are to bereinstalled, ensure to install indexed partsat the correct location.

Only use epoxy polyamide primer (C-204)for wet installations.

If a spring (13) requires replacement, itsadjacent spring must also be replaced(springs must be replaced in pairs). Allsprings and spring seats on the Frahmassembly must be of the same partnumber. After replacement of springs (13),

dynamic tuning of the Frahm is required.Refer to Chapter 18 or TB 407-99-14.

Springs (13) must be simultaneouslyinstalled in pairs on diametrically opposedsides.

Information on Frahm configurations andupgrades may be found in Table 62-1 andTable 62-2.

1. Assemble stop assembly (10, Figure 62-20) asfollows:

a. Apply epoxy polyamide primer (C-204) tobearing and liner assembly (7) and adapter (8) matingsurfaces.

b. Using a suitable arbor press and pressingsleeve (Workaid Item 4, Figure 62-18, Sheet 2) pressbearing and liner assembly (7, Figure 62-20) onadapter (8) while primer is still wet.

c. Temporarily install retaining plate (4) onadapter (8) and hold in place with hand pressure.

d. Using a feeler gauge, measure the gapbetween retaining plate (4) and adapter (8), as shownin Figure 62-20.

e. Measure the required shim thickness at fourlocations.

f. Add the four measurements and divide by fourto obtain the average required shim.

g. Subtract 0.001 to 0.003 inch (0.025 to0.076 mm) from the average required shim to obtain abearing pinch fit of 0.001 to 0.003 inch (0.025 to 0.076mm).

h. Peel shim (9) as required.

i. Apply epoxy polyamide primer (C-204) tomating surfaces of shim (9), adapter (8), and retainingplate (4).

j. Install shim (9) and retaining plate (4) onadapter (8) while primer is wet.

k. Apply Grade 2 corrosion preventivecompound (C-104) to bolt (6) shank and install bolt (6),washers (5 and 3) and nut (2) .


MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-101 Corrosion Preventive Compound, Grade 1



C-309 MEK

T

BHT-407-MM-6


l. Install the safety pin (1).

m. Apply corrosion preventive compound (C-101)to exposed portion of attaching hardware.

2. Apply epoxy polyamide primer (C-204) to themating surfaces of the housing assembly (13,Figure 62-18) and the stop assembly (17).

3. Using a suitable arbor press and pressing plug(Workaid Item 2, Figure 62-18, Sheet 2), press thestop assembly (17) in the housing assembly (13) whilethe primer is still wet.

4. Install the washers (19, Figure 62-18) and thebolts (18).

5. Install the spring seat (21) in the weight assembly(10) as follows:

a. Thoroughly clean the weight assembly (10)spring seat (21) bore with MEK (C-309).

NOTE

Ensure the spring seats are installed asshown on Figure 62-18, Detail A.

Proper cooling of the spring seat (21)should permit hand installation of the springseat (21) in the weight assembly (10).

b. Cool the spring seat (21) in a freezer at 0°F(-17.7°C).

c. Apply epoxy polyamide primer (C-204) to themating surfaces of the spring seat (21) and the weightassembly (10).

d. While the primer is wet and the spring seat(21) is cool, install the spring seat (21) in the weightassembly (10) with hand pressure. If required, asuitable arbor press and pressing plug (Workaid Item3, Figure 62-18, Sheet 2) or a soft mallet may be used.

6. Install the pad assembly (8) in the weightassembly (10) as follows:

CAUTION


a. Apply heat to the weight assembly (10).

b. Apply epoxy polyamide primer (C-204) to themating surfaces of the pad assembly (8) and theweight assembly (10).

c. Using a suitable press and pressing plug(Workaid Item 2, Figure 62-18, Sheet 2), press the padassembly (8, Figure 62-18) on the weight assembly(10) while primer is still wet.

NOTE

The weights (7) are to be installed in pairs.Each weight of a pair must be of the samepart number. The quantity of weights maychange during dynamic tuning.

7. Install the weights (7) in the weight assembly(10). Alternate the weight split lines by 90° from onerow to another. Ensure the same amount of weightspreviously removed is reinstalled.

8. Install the washers (6) and the nuts (5) .

9. Install the weight assembly (10) in the housingassembly (13).

10. To prevent damage to the housing assembly (13),temporarily install the plate (2) on the housingassembly.

11. Install the washers (4) and the bolts (3) .

12. Install the plugs (12) in the retaining plate (14) asfollows:

NOTE

Cooling of the plug (12) should permit handinstallation of the plug in the retainingplate (14).

a. Cool the plug (12) in a freezer at 0°F(-17.7°C).

b. Apply a coat of epoxy polyamide primer(C-204) to the mating surfaces of the retaining plate(14) and the plug (12).

c. While the primer is wet and the plug (12) iscool, install the plug in the retaining plate (14) withhand pressure. If required, a suitable arbor press and

T

T

BHT-407-MM-6


pressing plug (Workaid Item 3, Figure 62-18, Sheet 2)or a soft mallet may be used.

13. Install two pairs of diametrically opposed springs(9) in the housing assembly (13). Ensure the extendedportion of the spring is engaged in the spring seat (21)groove straight portion as shown in Detail A.

14. Install four threaded rods (Workaid Item 1,Figure 62-18, Sheet 2) through the retaining plate (11,Figure 62-19) and plugs (12) in the two diametricallyopposed pairs of threads in the weight assembly (15).Screw the threaded rods (7) until the threads are flushwith the inside surface of the weight assembly.

15. Tighten the inboard nut (9), and the washer (10),until it contacts the retaining plate (11).

16. Hold the threaded rod (7) outboard nuts (8) andequally tighten the four inboard nuts (9) to compressthe two diametrically opposed pairs of springs (13)until the retaining plate (11) contacts the housingassembly (1).

17. Apply corrosion preventive compound (C-104) onthe shanks of the eight bolts (4). Install the bolts andthe washers (3) on the two opposed retaining plates(11) .

18. Safety the bolts (4) in pairs.

19. Remove the four workaid threaded rods (7).

20. Repeat step 13 through step 19 for the two otherdiametrically opposed pairs of springs (13).

21. Remove the bolts (5) and the washers (6).

22. Remove the plate (2) from the housingassembly (1).

23. Inspect the springs (13) to ensure they arecorrectly installed and engaged in their springseat (14).

24. Install the plate (2) on the housing assembly (1).

25. Apply corrosion preventive compound (C-104) onthe shanks of bolts (5). Install the bolts and thewashers (6). Tighten the bolts and safety in pairs.

26. Apply corrosion preventive compound (C-101) onall exposed bolt heads.

62-57. FRAHM ASSEMBLY — INSTALLATION

NOTE

For flight operations with the Frahmassembly removed, refer to TB 407-03-51.

1. Put two maintenance platforms on either side ofthe helicopter, near the transmission.

2. Install the Frahm assembly (2, Figure 62-17) onthe main rotor hub assembly (5). The Frahm assemblylower surface cavity must match with the mast nut lockdevice.

3. Apply a layer of corrosion preventive compound(C-104) to the washers (4). Do not permit thecorrosion preventive compound to contaminatethreads.

NOTE

If necessary, omit the washers (4) tocorrectly engage the nuts (3).

4. Install the washers (4) and the nuts (3) on theFrahm assembly.

5. Apply a layer of corrosion preventive compound(C-101) to the nuts (3), washers (4), and exposedthreads.

6. Align the index mark and install the cover (1) onthe Frahm assembly (2); attach with screws (6) .

62-58. MAIN ROTOR SYSTEM — MAINROTOR HUB ASSEMBLY

The main rotor hub assembly (Figure 62-33) attachesthe main rotor blades to the helicopter. The main rotor

T

T


MATERIALS REQUIRED

NUMBER NOMENCLATURE



T

T

BHT-407-MM-6


hub assembly transmits the drive torque from the mast(13) to the blades and permits the blade pitch changemotion and reacts to the blade forces. The majorcomponents of the main rotor hub assembly consist ofthe following:

• Mast nut (1)

• Upper cone (2)

• Drive ring set (39)

• Upper hub plate (6)

• Lower hub plate (37)

• Center cone set or integral mast centercone (14)

• Elastomeric lead-lag damper (8)

• Elastomeric shear bearing (20)

• Elastomeric pivot (feathering) bearing (9)

• Main rotor blade grips (21)

• Yoke (7)

• Lower cone (15)

• Pitch horns (17)

The main rotor hub assembly is attached to the mast(13) with a mast nut (1), an upper cone (2), a centercone set (14), and a lower cone (15). The main rotorhub assembly is aligned on the mast by a masterspline. The master spline determines where the redblade will be. For the color codes of the blades, referto Chapter 11.

An elastomeric pivot (feathering) bearing (9) attachesthe outboard end of the main rotor blade grips (21) tothe outboard end of the yoke (7). An elastomeric shearbearing (20) attaches the inboard end of the main rotorblade grips (21) to the elastomeric lead-lag damper (8)that is attached to the upper and lower hub plates (6and 37). The dampers, bearings, and yoke permit theblade coning, droop, lead-lag, and blade pitch changemotions.

The pitch horns (17) are attached to the main rotorblade grips (21) and supply an attachment point for the

pitch links (16). The pitch horns (17) turn the blade onthe elastomeric shear bearing (20). This changes theangle of attack (pitch) of the main rotor blades.

The main rotor blade’s upper droop stops (22) areattached to the upper hub plate (6) and the lowerdroop stops (22) are attached to the lower hub plate(37). The main rotor blade up and down stops keepthe yoke (7) flex (cone and droop) in operational limits.

62-59. MAIN ROTOR HUB ASSEMBLY —REMOVAL


NUMBER NOMENCLATURE

407-210-001-101 Hub Support

407-210-002-101 Support

7500-pound (3402-kg) Minimum Capacity

Clevis

NAS1212P17AA80or Equivalent

Strap Assembly (Qty 4)

PD1201 or Equivalent Torque Multiplier

SIM 402 1 1/4 Inch Socket (Snap-On)

NOTES:

1.75 inches (44.5 mm) wide, 72 inches(183 cm) long, and rated at 2500 pounds(1134 kg) each.

As an alternative, use the applicableworkaid shown in the BHT-407-CR&O,Chapter 62.


MATERIALS REQUIRED

NUMBER NOMENCLATURE


C-418 Masking Tape

2

1

1

2

BHT-407-MM-6


1. Put the maintenance platforms adjacent to thetransmission on the left and right sides of thehelicopter.

2. Examine the main rotor hub assembly (24,Figure 62-33), main rotor blades, and pitch links (16)for color coded marks (dots). If the color coded marksare missing, apply new marks (dots). Refer toChapter 11.

3. Remove the main rotor blades (3, Figure 62-7and paragraph 62-12).

4. Prepare the helicopter by aligning the mastvertically within 0.5° to remove the main rotor hubassembly. This can be achieved by one of threemethods: jacking, ground handling wheels, or hoist.

5. Place wooden pads (dimensions approximately 6inches (152.4 mm)) under the skids (at forwardcrosstube/skid tube mating area) and lower thehelicopter. If needed, change the dimensions of thewooden pads to achieve the proper mast angle.

6. If installed, remove the cover and the Frahmassembly (paragraph 62-51).

7. For S/N 53000 through 53631 Pre TB 407-05-66,remove the bolts (5, Figure 62-31), washers (6), andlock (7).

8. For S/N 53632 and subsequent, or S/N 53000through 53631 Post TB 407-05-66, remove the bolts(5, Figure 62-32), washers (6), lock (7), andretainer (8).

NOTE

A 3/4 inch (19 mm) drive torque wrench (9,Figure 62-31 or 10, Figure 62-32) with thecorrect type 1.25 inch (32 mm) socket canbe used to remove the mast nut (4) as analternative to the torque multiplier (2). Thetorque wrench and socket must be capableof a minimum of 1000 foot-pounds(1356 Nm) torque.

9. Install the support 407-210-002-101 (1,Figure 62-31 or Figure 62-32) and the torque multiplier(2) on the upper plate assembly (8).

10. Loosen the mast nut (4).

11. Remove the torque multiplier (2), support (1), andmast nut (4).

12. Remove the cotter pin (19, Figure 62-33), nut(18), washers (12), bolt (10), and floating bushing (11)from each of the pitch links (16) and the pitchhorns (17).

13. Move the pitch links (16) out of the way and holdthem clear of the main rotor hub assembly (24) withmasking tape (C-418).

14. Examine the lower cone (15) for the red indexmark that is aligned with the centerline of the redblade. If the red index mark is not there, apply a layerof red polyurethane coating (C-245) to the area of thecone shown in Figure 62-33.

NOTE

Put a cloth around the mast (13) over theswashplate drive assembly to preventdamage if the lower cone (15) falls.

15. For S/N 53000 through 53066 Pre TB 407-99-16,remove the bolts (6, Figure 62-41) and the washers (5)from the lower cone (4). Carefully lower the lower conedown the mast (3).

16. For S/N 53067 and subsequent or S/N 53000through 53066 Post TB 407-99-16, remove the nuts(5, Figure 62-42), washers (4), and bolts (3) from thelower cone (7). Carefully lower the lower cone downthe mast (6).

17. Carefully remove the upper cone (2,Figure 62-33).

18. Install the strap assemblies (2, Figure 62-45) onthe main rotor hub assembly (3) as follows:

a. Install one strap assembly (2) around eacharm of the hub upper plate (6).

b. Attach the ends of each strap assembly (2) tothe clevis (8).

c. Attach the clevis (8) to the hoist (1).

d. Operate the hoist (1) until the strapassemblies (2) are tight.

BHT-407-MM-6

62-00-002 OCT 2007 Rev. 24 Page 93

Figure 62-31. Mast Nut (S/N 53000 through 53631 Pre TB 407-05-66)— Removal and Installation

407MM_62_0023_C02

1. Support (407-210-002-101)2. Torque multiplier

3. Blade grip

4. Mast nut

5. Bolt

6. Washer

7. Lock

8. Upper plate assembly

9. Torque wrench/breaker bar

(881 TO 949 Nm)

650 TO 700 FT-LBS

(6.8 TO 9.0 Nm)

60 TO 80 IN-LBS

LOCKWIRE (C-405) OR SAFETY


NOTES

1

2

2

4

9

5

6

7

8

3 1

1

1


2

3

Apply a coating of corrosion preventive compound (C-104) to all bolt shanks prior to installation. Do

not apply corrosion preventive compound to bolt threads.

A 0.75 inch (19.05 mm) drive torque wrench or breaker bar can be used instead of the torque multiplier.

Both must be able to supply 1000 foot-pounds (1355.8 Nm) of torque.

3 Apply a coating of corrosion preventive compound (C-101) to all bolt heads, washers, nuts and

exposed threads after installation.

1

1

2

2

CABLE (C-152) AND FERRULE (C-153)

2

1 1

BHT-407-MM-6

62-00-00Page 94 Rev. 23 7 NOV 2006

Figure 62-32. Mast Nut (S/N 53000 through 53631 Post TB 407-05-66 andS/N 53632 and Subsequent) — Removal and Installation (Sheet 1 of 2)

407MM_62_0070

1. Support (407-210-002-101)

2. Torque multiplier

3. Blade grip

4. Mast nut

5. Bolt

6. Washer

7. Lock

9. Upper plate assembly

10. Torque wrench/breaker bar

(1017 TO 1085 Nm)

750 TO 800 FT-LBS

(6.8 TO 9.0 Nm)

60 TO 80 IN-LBS

LOCKWIRE (C-405)


8. Retainer

2

2

10

9

3

1

SEE DETAIL A

1

1

4

6

7

5

DETAIL A

SEE DETAIL B

2

1

1


3

4

11

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 95

Figure 62-32. Mast Nut (S/N 53000 through 53631 Post TB 407-05-66 andS/N 53632 and Subsequent) — Removal and Installation (Sheet 2 of 2)

407MM_62_0071

NOTES

1

2

3

DETAIL B

(VIEW LOOKING DOWN)

8

7

4

8

7

HOLE

LOCK TANGS 2

2

2

Apply a coating of corrosion preventive compound (C-104) to all bolt shanks prior to installation. Do not

apply corrosion preventive compound to bolt threads.

Apply a coating of corrosion preventive compound (C-101) to all bolt heads, washers, nuts and exposed

threads after installation.

4

Install the lock (7) so that the related hole in retainer (8) is positioned within the tangs of lock (7). Do not

allow any portion of the related hole in retainer (8) to be positioned outside of the lock tangs.

A 0.75 inch (19.05 mm) drive torque wrench or breaker bar can be used instead of the torque multiplier.

Both must be able to supply 1000 foot-pounds (1355.8 Nm) of torque.

BHT-407-MM-6

62-00-00Page 96 Rev. 23 7 NOV 2006

Figure 62-33. Main Rotor Hub Assembly (Sheet 1 of 6)407MM_62_0032_C01

15

14

13

1918

12

17

16 12

109

21

22

1

3

45

24

23

20

7

8

11

6

MASTER SPLINE

(RED BLADE)

DSEE DETAIL

ASEE DETAIL

28

27

29

SEE DETAIL B1 AND B2

2

7

4

3

4

3

3

3

3

RED INDEX PAINT

7

5

8

3

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 97


DETAIL A

25

19

12

1716

12

10

11

26

B1DETAIL

S/N 53000 THROUGH 53414 PRE TB 407-00-22

DETAIL B2

11

10

12

1617

12

18

19

BUSHING

FLANGE

11

CSEE DETAIL

18

3

6

44

44

5

S/N 53000 THROUGH 53414 POST TB 407-00-22

AND S/N 53415 AND SUBSEQUENT

BHT-407-MM-6

62-00-00Page 98 Rev. 23 7 NOV 2006


21

32

27

31

30

9

28

8

3520

40

34

33

DETAIL C

17

7

5

2

1

3

6

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 99

Figure 62-33. Main Rotor Hub Assembly (Sheet 4 of 6)407MM_62_0050

DDETAIL

23

1

6

7

36

37

2

38

BHT-407-MM-6

62-00-00Page 100 Rev. 23 7 NOV 2006


21.22.23.24.25.26.27.28.29.30.

Main rotor blade gripsDroop stops (upper and lower)BoltMain rotor hub assemblyNutWasherBoltAdapter assemblyBoltBolt

31. Bolt

Buffer pad35.NutBoltNut

34.33.32.

36.37.38.

Lower cone seatLower hub plateNut

39. Drive ring set

14.15.16.17.18.

Center cone setLower conePitch linkPitch hornNut

Elastomeric shear bearingCotter pin

MastWasherFloating bushingBoltElastomeric pivot (feathering) bearingElastomeric lead-lag damperYokeUpper hub plateLock or lock and retainerWasherBoltUpper coneMast nut

20.19.

13.12.11.10.

9.8.7.6.5.4.3.2.1.

40. Bolt

1

58 TO 62 FT-LBS(78 TO 84.1 Nm)

2

75 TO 95 IN-LBS(8.5 TO 10.7 Nm)3

90 TO 110 IN-LBS(10.2 TO 12.4 Nm)4

300 TO 336 IN-LBS(33.9 TO 38.0 Nm)

5

50 TO 70 IN-LBS(5.6 TO 7.9 Nm)

6

50 TO 80 IN-LBS(5.6 TO 9.0 Nm)

7

160 TO 190 IN-LBS(18.1 TO 21.5 Nm)



THIXOGREASE (C-561)3

SEALANT (C-308)

LOCKWIRE (C-405)

9

2

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 101

Figure 62-33. Main Rotor Hub Assembly (Sheet 6 of 6)407MM_62_0069

NOTES

The recommended installation torque range and maximum permitted torque are given.1.

When you torque the nut, make sure you can align it for the installation of the

You can damage the nut if you torque the nut more than the given values while you align

Add the tare torque to the given torque value.

cotter pin. To prevent the nut from becoming thread bound on the bolt shank,

a thick (NAS1149F0563P) or a thin (NAS1149F0532P). You must always put the thin washeryou can use a quantity of two washers under the nut. The washer under the nut can be

next to the nut.

it for the cotter pin. Replace the nut if you think it is damaged.

Use the washers, P/N NAS1149F0663P or AN960-616, on the unthreaded portion of the stud. Use the washers, P/N NAS1149F0563P or AN960-516, on the threaded portion of the stud. The washer quantity is as required.

Make sure that the floating bushing is installed with the flange against the pitch link (S/N 53000 through 53414, Pre TB 407-00-22).

On S/N 53000 through 53631 Post TB 407-05-66 and S/N 53632 and subsequent, the center cone set has been replaced with an integral one piece cone on the mast.

Lock and retainer are applicable on S/N 53000 through 53631 Post TB 407-05-66 and S/N 53632 and subsequent.

3

4

5

6

7

8


9

2 Apply a coating of corrosion preventive compound (C-104) to all bolt shanks prior to installation. Do not apply corrosion preventive compound to bolt threads.

BHT-407-MM-6


19. Carefully lift the main rotor hub assembly (3) offthe mast (7).

NOTE

As an alternative to the hub support407-210-001-101, use the applicableworkaid shown in the BHT-407-CR&O,Chapter 62.

20. Lower the main rotor hub assembly (3) and put iton the hub support (5).

NOTE

For S/N 53632 and subsequent or S/N53000 through 53631 Post TB 407-05-66,the center cone set has been replaced withan integral one-piece cone on the mast.Step 21 is not required.

21. If applicable, break the lockwire and remove thecenter cone set (14, Figure 62-33) from the mast (13).

22. Remove the lower cone (15) from the mast (13).

62-60. MAIN ROTOR HUB ASSEMBLY —ASSEMBLY/DISASSEMBLY

For the assembly and disassembly procedures of themain rotor hub assembly, refer to the BHT-407-CR&O.

62-61. MAIN ROTOR HUB ASSEMBLY —INSPECTION AND REPAIR

NOTE

Refer to the BHT-407-CR&O for wear,damage, repair limits, and replacementprocedures not contained in this chapter.

1. Clean the main rotor hub assembly (24,Figure 62-33) with a cloth dampened with drycleaningsolvent (C-304).

2. Examine the lower hub plate (37) for cracks andmechanical and/or corrosion damage.

NOTE

Splinters in the yoke (7) occur when fibersin the surface plies have broken loose orseparated from the lower plies. You canusually find splinters at the machined ormolded edges of the laminate. Edgedelamination in the yoke occurs when theplies separate from each other.

3. Examine the yoke (7) for voids, splinters, andedge delamination.

4. Examine the main rotor blade grips (21) forcracks and mechanical and/or corrosion damage.

5. Examine the bolts (27) and nuts (32) that attachthe adapter assembly (28) to the yoke (7). Ensure thebolts and nuts are tight. Replace all corrosionpreventive compound (C-101) that has worn away.

6. Examine the bolts (29) that attach the balanceweights to the adapter assembly (28). Ensure the boltsare tight. Replace all corrosion preventive compound(C-101) that has worn away.

7. Examine the bolts (30 and 31) on the elastomericpivot (feathering) bearings (9). Ensure the bolts aretight. Replace all corrosion preventive compound(C-101) that has worn away.

8. Examine the bolts (33) and nuts (34) that attachthe elastomeric shear bearing (20) to the elastomericlead-lag damper (8). Examine the bolts (40) that attach


MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-021 Solid Film Lubricant





C-308 Sealant

C-426 Masking Tape


MATERIALS REQUIRED

NUMBER NOMENCLATURE

BHT-407-MM-6


the elastomeric shear bearing to the main rotor bladegrip (21). Ensure the hardware is tight. Replace allcorrosion preventive compound (C-101) that has wornaway.

9. Examine the pitch horn (17) for corrosion, cracks,and scratches. Examine the buffer pad (35) fordebonding or voids.

NOTE

Misalignment of the radial injection lines onthe shear bearings (20) outboard surface isnot cause for rejection. Refer to InformationLetter 407-07-93 for more details.

10. Examine the elastomeric shear bearings (20) forthe damage that follows:


• Elastomeric material that is ejected outbetween the shims

• Corrosion on the metal part of the bearing

• Cracks in the metal part of the bearing

11. Examine the elastomeric pivot (feathering)bearings (9) for the damage that follows:


• Elastomeric material that is ejected outbetween the shims

• Corrosion on the metal part of the bearing

• Cracks in the metal part of the bearing

12. Examine the elastomeric lead-lag dampers (8) forthe damage that follows:

• Corrosion to the metal part of the elastomericlead-lag damper (8)

• Tears, cracks, or debonded areas in theelastomer

• The elastomeric lead-lag damper (8) is nottouching the yoke (7)

13. Examine the nuts (25). Ensure the nuts are tight.Replace all corrosion preventive compound (C-101)that has worn away.

14. Examine sealant (C-308) applied at the followinglocations for condition. If sealant (C-308) is damagedto an extent where water or moisture can penetratethe joint, replace sealant (C-308) (Figure 62-33,Detail D).

• Around the main rotor hub assembly throughthe bolts (23) heads

• At the joint between the upper hub plate (6)and the yoke (7)

• At the joint between the yoke (7) and the lowerhub plate (37)

• At the joint between the lower hub plate (37)and the lower cone seat (36)

15. Examine the upper hub plate (6) for cracks andmechanical and/or corrosion damage.

16. Examine the mast nut (1) for cracks andmechanical and/or corrosion damage (Figure 62-34).Examine the inside surface for missing corrosionpreventive compound (C-101).

17. If required, repair or replace the finish of the mastnut (1) as follows:

a. As applicable, touch-up repair or replace thecoating of solid film lubricant (C-021) on the area ofthe mast nut (1) shown in Figure 62-34A per theinstructions in the BHT-ALL-SPM, Chapter 3.

b. If necessary, restore the paint on the mast nut(1) as follows:

(1) Cover the areas of the mast nut that donot require paint with masking tape (C-426), as shownin Figure 62-34A.

(2) Apply one coat of epoxy polyamideprimer (C-204) on the area of the mast nut shown inFigure 62-34A per the instructions in theBHT-ALL-SPM, Chapter 4.

(3) Apply two coats of polyurethane coating(C-245), color code 16440 per FED-STD-595, on thearea of the mast nut shown in Figure 62-34A per theinstructions in the BHT-ALL-SPM, Chapter 4.

BHT-407-MM-6

62-00-00Page 104 Rev. 23 7 NOV 2006

Figure 62-34. Mast Nut — Wear, Damage, and Repair Limits (Sheet 1 of 2)


4.

3.

2.

1.




NO.REFLTR CHARACTERISTIC

0.030 inch (0.762 mm)

Not critical

0.005 inch (0.127 mm)

0.010 inch (0.254 mm)

Measure

Measure

Measure

LIMITINSPECTIONMETHOD

5.

A, B

D, F

B

A

D Maximum area perfull depth repair

0.010 square inch (6.4516 mm2)Measure

MAST NUT (407-010-106) MATERIAL: CRES STEEL

407MM_62_0087

C (SPLINES)

D(LOWER SURFACE)

E

B

A

6. F Maximum area perfull depth repair


7. A, B Number of repairs Not critical

8. D Number of repairs One per each 90° quadrant

G (BORE)

F(INSIDE SURFACE)

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 105

Figure 62-34. Mast Nut — Wear, Damage, and Repair Limits (Sheet 2 of 2)

Number of repairs

10.

15.

14.

9.


Mechanical/corrosionthread damage

Depth:Length:Number:

Mechanical/corrosionspline damage

Cracks

Depth:Length:Number:

1/3 of thread0.050 inch (1.27 mm)Two

1/3 of spline1/2 of spline2 per 1/2 circumference


One per surface

0.060 inch (1.524 mm)

None

Measure

Measure

NDI


11.

A

C

F

B Mechanical/corrosionedge chamfer damage

0.030 inch (0.762 mm)Measure

407MM_62_0088

12. D, F

E



Measure13.

BHT-407-MM-6


Figure 62-34A. Mast Nut — Finishing407MM_62_0094

SECTION A-A

A

A

HOLE

NO ORGANIC FINISH

THREADS

2

21

2

3

0.0 TO 0.06 IN.(0.0 TO 1.5 mm)

1

2

3

NOTESApply solid film lubricant (C-021) only.

Apply one coat of epoxy polyamide primer (C-204) only.

Apply one coat of epoxy polyamide primer (C-204) and two coats of polyurethanecoating (C-245), color code 16440 per FED-STD-595, except where indicated.

BHT-407-MM-6

62-00-00ECCN EAR99

18. Examine the lock or lock and retainer(s) (5,Figure 62-33) for cracks and mechanical and/orcorrosion damage (Figure 62-35, Figure 62-36, andFigure 62-37).

19. Examine the upper cone (2, Figure 62-33) forcracks and mechanical and/or corrosion damage(Figure 62-38).

NOTE

For S/N 53632 and subsequent or S/N53000 through 53631 Post TB 407-05-66,the center cone set has been replaced withan integral one piece cone on the mast.

NOTE

If installed, the center cone set (14) is amatched set and is serialized.

20. If installed, examine the center cone set (14,Figure 62-33) for wear, cracks, mechanical damage,and corrosion damage (Figure 62-39).

21. Examine the lower cone (15, Figure 62-33) andthe lower cone seat (36) for cracks and mechanicaland/or corrosion damage. Refer to Figure 62-40 forthe wear, damage, and repair limits of the lower cone.

22. Examine all external bolts, nuts, and washers formissing corrosion preventive compound (C-101).Reapply corrosion preventive compound (C-101) ifrequired.

23. Examine the mast (13, Figure 62-33) splines forwear, broken splines, mechanical damage, andcorrosion damage.

16 FEB 2012 Rev. 34 Page 106A

BHT-407-MM-6

ECCN EAR9962-00-00

Figure 62-35. Mast Nut Lock (407-010-109) — Wear, Damage, and Repair Limits


2.

6.

1.


SplinesDepth:Length:Number:

Cracks

1/3 of spline1/2 of splineTwo


0.030 inch (0.762 mm)

0.010 inch (0.254 mm)

NoneNDI

Measure

Measure


3.

B

A

C Mechanical/corrosionbore damage

0.002 inch (0.051 mm)1/4 circumference

Measure

MAST NUT LOCK (407-010-109)MATERIAL: CRES STEEL

407MM_62_0089

4. C

D

Maximum borediameter


Measure5.

B (LOWER SURFACE)

C (BORE)

A (ALL SURFACES)

D (SPLINES)

Page 106B Rev. 34 16 FEB 2012

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 107

Figure 62-36. Mast Nut Lock (407-010-117) — Wear, Damage, and Repair Limits (Sheet 1 of 2)

MAST NUT LOCK (407-010-117)MATERIAL: CRES STEEL

NO.

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

16.

REFLTR

A

B

A, B

A, B

C

C

C

C

C

D

D

D

D

D

E

E

CHARACTERISTIC

Spline wear

Spline wear

Corrosion

Spline damage

Mechanical/corrosion


Number of repairs

Mechanical/corrosion edge chamferdamage


Mechanical/corrosion


Number of repairs

Mechanical/corrosion edge chamferdamage


Mechanical/corrosion bore damage


INSPECTIONMETHOD

Measure over0.1080 inch (2.7432 mm)diameter pins

Measure over0.0400 inch (1.016 mm)diameter pins

Visual

Visual

Visual/measure

Measure

Measure

Visual/measure

Measure

Measure

LIMIT

2.8569 inch (72.5653 mm)maximum diameter

3.2952 inch (83.6981 mm)minimum diameter

Only superficial corrosion thatcan be removed by handpolishing with abrasive pad(C-407) is permitted

None permitted

0.003 inch (0.0762 mm)

0.010 square inch (6.4516 mm2)

One per area

0.010 inch (0.254 mm)

One per edge

0.006 inch (0.1524 mm)

Not critical

Not critical

0.020 inch (0.508 mm)

Not critical


One per bore

CB

D

2

2

407MM_62_0083

A

E

2

2

2

BHT-407-MM-6

62-00-00Page 108 Rev. 23 7 NOV 2006

Figure 62-36. Mast Nut Lock (407-010-117) — Wear, Damage, and Repair Limits (Sheet 2 of 2)

LETTER DESIGNATION

A

B

C

D

E

SPLINE A

SPLINE B

BORE

NOTES

1.

3.


Damage limits given are after repair.

Surface finish after repair. Apply brush cadmium plating and reapply solid film lubricant per BHT-ALL-SPM.

2

407MM_62_0084

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 109

Figure 62-37. Retainer — Wear, Damage, and Repair Limits (Sheet 1 of 2)407MM_62_0085

MAST NUT RETAINER (407-010-118)MATERIAL: CRES STEEL

NO. LTRREF

CHARACTERISTIC METHODINSPECTION

LIMIT

1. A Spline wear Measure over

0.0360 inch (0.9144 mm)

diameter pins

3.2166 inch (81.7016 mm)

maximum diameter

2. A Spline corrosion Visual Only superfical corrosion that

can be removed by hand

polishing with abrasive pad

(C-407) is permitted

3. A Spline damage Visual None permitted

4. B Mechanical/corrosion Visual/measure 0.004 inch (0.1016 mm) 2

5. B Measure 0.010 square inch (6.4515 mm²)Maximum area per

full depth repair

6. B One per areaNumber of repairs

7. B Measure 0.020 inch (0.508 mm) 2Mechanical/corrosion

edge chamfer damage

8. B One per edgeNumber of edge

chamfer damage

9. C, D Visual/measure 0.008 inch (0.2032 mm) 2Mechanical/corrosion

10. C Measure 0.030 square inch (19.3548 mm²)Maximum area per

full depth repair

11. C One per areaNumber of repairs

12. C, D Measure 0.020 inch (0.508 mm) 2Mechanical/corrosion

edge chamfer damage

13. C One per edgeNumber of edge

chamfer damage

14. D Measure Not criticalMaximum area per

full depth repair

15. D Not criticalNumber of repairs

16. D Not criticalNumber of edge

chamfer damage

E

A

C D B

F

BHT-407-MM-6

62-00-00Page 110 Rev. 23 7 NOV 2006

Figure 62-37. Retainer — Wear, Damage, and Repair Limits (Sheet 2 of 2)

MAST NUT RETAINER (407-010-118)MATERIAL: CRES STEEL

NO.

17.

18.

19.

REFLTR

E, F

E, F

E, F

CHARACTERISTIC

Mechanical/corrosion bore damage


Maximum bore diameter

INSPECTIONMETHOD

Measure

Measure

LIMIT


Not critical

0.269 inch (6.8326 mm)

LETTER DESIGNATION

ABCDE, F

SPLINE

BORES

NOTES

1.

3.


Damage limits given are after repair.

Surface finish after repair. Apply brush cadmium plating and reapply solid film lubricant per BHT-ALL-SPM.

2

2

407MM_62_0086

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 111

Figure 62-38. Upper Cone — Wear, Damage, and Repair Limits


4.

3.

2.

1.


Number of repairs



0.010 inch (0.254 mm)

0.020 inch (0.508 mm)

Two per surface

0.100 square inch (64.516 mm2)

Visual

Measure

Measure


5.

A

Number of edge chamferdamage repairs

Two per edgeVisual

Measure

UPPER CONE (407-010-110)MATERIAL: CRES STEEL

407MM_62_0090

6. Cracks NoneNDI

A (ALL SURFACES)

BHT-407-MM-6


Figure 62-39. Center Cone Set — Wear, Damage, and Repair Limits

AA

VIEW A-A

A(ALL SURFACES)


2.

1.


Cracks


0.010 inch (0.254 mm)


Measure


3.

A

A

A Number of repairs Two per surfaceVisual

CENTER CONE SET (407-010-114)MATERIAL: ALUMINUM BRONZE

407MM_62_0091

4. A

A



NDI None5.

Split cone is matched set and serialized.

NOTE

BHT-407-MM-6

62-00-007 NOV 2006 Rev. 23 Page 113

Figure 62-40. Lower Cone — Wear, Damage, and Repair Limits

B (BORE)

A (ALL SURFACES)

SECTION D-D

C(INSIDE DIAMETER)

TEFLON DACRON MATERIAL


2.

1.



0.010 inch (0.254 mm)


Measure


3.

A

A

A Number of repairs Two per surfaceVisual

LOWER CONE (407-010-104)MATERIAL: CRES STEEL

407MM_62_0092

4. A Mechanical/corrosionedge chamfer damage


5. B Diameter 0.271 inch (0.6883 mm)Measure

6. B

C



Measure

Visual7.

Cracks

Inside diameter TeflonDacron material

No exposed metalpermitted

NDI None8.

D

D

BHT-407-MM-6


62-62. MAIN ROTOR HUB ASSEMBLY —(S/N 53000 THROUGH 53066PRE TB 407-99-16) — INSTALLATION

1. Put the maintenance platforms adjacent to thetransmission on the left and right side of the helicopter.

2. Prepare the helicopter by aligning the mastvertically within 0.5° to receive the main rotor hubassembly. This can be achieved by one of threemethods: jacking, ground handling wheels, or hoist.

3. Place wooden pads (dimensions approximately 6inches (152.4 mm)) under the skids (at forwardcrosstube/skid tube mating area) and lower helicopter.If needed, change the dimensions of the wooden padsto achieve the proper mast angle.

CAUTION

THE MAIN ROTOR BLADES AND THEMAIN ROTOR HUB ASSEMBLYCOMPONENTS ARE COLOR CODEDFOR POSITION. ALL COMPONENTS OFONE COLOR THAT ARE REMOVEDMUST BE INSTALLED IN THE SAMECOLOR LOCATION.

4. Clean the bolts (3, Figure 62-33), washers (4),and lock (5) with drycleaning solvent (C-304). Ensurethat there is no oil, grease, or corrosion preventivecompound on the bolts, washers, and lock.

5. Clean the mast nut lock (5) bolt threaded holes inthe upper hub plate (6).


NUMBER NOMENCLATURE

407-210-001-101 Hub Support

407-210-002-101 Support

7500-pound (3402-kg) minimum capacity

Clevis

NAS1212P17AA80or equivalent




NOTE:



MATERIALS REQUIRED

NUMBER NOMENCLATURE



C-152 Safety Cable

C-153 Ferrule

C-158 Sealant



1

1

1

1

2

C-308 Sealant

C-405 Lockwire

C-561 Grease

NOTES:

Use safety cable (C-152) with ferrule(C-153) as an alternative to lockwire(C-405).

Alternative for sealant (C-308).



NUMBER NOMENCLATURE

1

2

BHT-407-MM-6


NOTE

Clean the bolts and bolt holes to ensurethat the tare torque (run torque) will beequal when you install the bolts.

6. Clean all bolts (6, Figure 62-41) with drycleaningsolvent (C-304). Ensure that there is no oil, grease, orcorrosion preventive compound on the bolts.

7. Clean all threaded bolt holes in the lower coneseat (2, Figure 62-41) and the lower cone (4).

8. Ensure that the lower cone (4) red index mark iscorrect as follows:

a. Put the lower cone (4) on a table with thebevelled side down (Detail A).

b. Align the cone split at the 12 o’clock position.The red index mark should be at the 11 o’clockposition as shown in Detail A.

c. If there is no index mark, apply redpolyurethane coating (C-245) at the proper location.

9. Install the lower cone (4) on the mast (3) with thebevelled side up.

CAUTION

DO NOT APPLY GREASE (C-561) ANDCORROSION PREVENTIVE COMPOUND(C-101 AND C-104) TO METALL ICBEARINGS, ELASTOMERIC BEARINGS,SEALS, TEFLON, AND TEFLON COATEDPARTS. GREASE (C-561) ANDCORROSION PREVENTATIVECOMPOUND (C-101 AND C-104) CAUSEDAMAGE TO METALLIC BEARINGS,ELASTOMERIC BEARINGS, SEALS,TEFLON, AND TEFLON COATED PARTS.

ENSURE THAT THERE IS NOGREASE (C-561) BETWEEN THECENTER CONE SET (7) TEFLON ANDTHE MAST (3).

10. Apply a layer of grease (C-561) to the mast (3)splines. Do not apply grease (C-561) to the mating

area of the center cone set (7) Teflon and the mast orto the mast nut threads.

11. If there is grease (C-561) between the centercone set (7) and the mast (3), remove it.

12. Attach the center cone set (7) with lockwire(C-405) (9). Ensure the lockwire does not come out ofthe groove in the center cone set (7).

13. Apply a thin layer of grease (C-561) to the outsideof the center cone set (7) as shown in Figure 62-41.






15. Lift the main rotor hub assembly (3) off the hubsupport (5) and move it above the mast (13,Figure 62-33).

NOTE

Loosening the hub through the bolts (23) ispermitted if restriction is encountered whilelowering the main rotor hub assembly onthe mast. Torque the nuts (38) once theassembly sits on the center cone set(BHT-407-CR&O, Chapter 62).

16. Align the master tooth of the main rotor hubassembly with the master spline of the mast (13,Figure 62-45). Carefully lower the main rotor hubassembly onto the mast.

17. Apply a thin layer of corrosion preventivecompound (C-104) on the grip portion (shoulder orunthreaded portion) of the bolts (6, Figure 62-41) andon the washers (5). Do not allow corrosion preventivecompound (C-104) on the threaded portion of thebolts (6).

T

BHT-407-MM-6


Figure 62-41. Main Rotor Hub Center Cone Set, Lower Seat, and Lower Cone (S/N 53000 through 53066 Pre TB 407-99-16) (Sheet 1 of 3)

407MM_62-0024a

SEE DETAIL B

SEE DETAIL A

2

6

3

1

410

5

CSEE DETAIL

ADETAIL

LOWER CONE SPLITAT 12 O'CLOCK

RED INDEX MARK AT11 O'CLOCK (C-203)

(SHOWN WITH BEVELLED SIDE DOWN)

23

BHT-407-MM-6


Figure 62-41. Main Rotor Hub Center Cone Set, Lower Seat, and Lower Cone(S/N 53000 through 53066 Pre TB 407-99-16) (Sheet 2 of 3)

407MM_62_0024b

7

9

8

3

DETAIL B

DETAIL

5

6

2

4

3

C

10

SEALANTNO

RED INDEX MARK

1

SEE DETAIL E

SEE DETAIL E3

1

2 4SEE DETAIL D

2

6

5

4

RADIUS

DETAIL D

7

MAST JOURNAL

BHT-407-MM-6


Figure 62-41. Main Rotor Hub Center Cone Set, Lower Seat, and Lower Cone(S/N 53000 through 53066 Pre TB 407-99-16) (Sheet 3 of 3)

407MM_62_0024c

NOTES

The final measurement must be within 0.010 inch (0.25 mm) of each other.

DETAIL E

1. Mast splines

3. Mast4. Lower cone5. Washer6. Bolt7. Center cone set8. Center cone seat9. Lockwire

2. Lower cone seat

10. Lower plate

Safety in pairs.

TORQUE SEQUENCE

5

9

10

3

1

7

8

2

64

(VIEWED FROM BELOW LOOKING UP)

C RED BLADE & MASTER TOOTH

2

4

6RED INDEXPAINT (C-203)

Apply corrosion preventive compound (C-101) to all exposed bolt heads after installation.

101 THROUGH

42

CONE SPLIT MUST REMAINOPEN AFTER INSTALLATIONIS COMPLETE

85 TO 105 IN-LBS(9.6 TO 11.9 Nm)

THIXOGREASE (C-561)



SEALANT (C-308)

1

2

3

4

Apply a coating of corrosion preventive compound (C-104) to all bolt shanks prior to installation.Do not apply corrosion preventive compound to bolt threads.

6

4

3

LOCKWIRE (C-405) OR SAFETY

1

CABLE (C-152) AND FERRULE (C-153)

2

3

5

Apply sealant (C-308 or C-158) as shown.6

An overlap of 0.10 inch (2.54 mm) on the adjacent radius is permitted.7

Apply sealant (C-308 or C-158) as shown and make sure the sealant completely covers themast journal under the lower cone (4).

BHT-407-MM-6


CAUTION

ENSURE THAT THERE IS NOGREASE (C-561) ON THE LINER OF THELOWER CONE (4). GREASE (C-561)CAUSES DAMAGE TO THE LINER.

NOTE

Ensure the red index mark on the lowercone (4) is aligned with the center line ofthe red blade position on the hub.

18. Install the lower cone (4) on the lower coneseat (2).

19. Install the bolts (6) and the washers (5) fingertight. Do not tighten the bolts at this time.

20. Remove the strap assemblies (2, Figure 62-45)from the hub upper plate (6).

CAUTION

MAKE SURE THAT GREASE (C-561) ISAPPLIED TO THE SURFACES OF THEUPPER CONE (2, Figure 62-33) AND THEASSOCIATED MATING SURFACES OFTHE UPPER HUB PLATE (6) AND THEMAST NUT (1). OTHERWISE, IT WILL BEDIFFICULT TO REMOVE THE MAST NUTAT THE NEXT REQUIREMENT FORREMOVAL.

21. Apply grease (C-561) to the entire surface of theupper cone (2) as well as the mating conical suface ofthe upper hub plate (6) and the mating surface of themast nut (1). Install the upper cone.

22. Start the mast nut (4, Figure 62-31) on the mast.

NOTE

A 3/4-inch (19 mm) drive torque wrench (9)with a minimum 1000 foot-pound(1360 Nm) capacity can be used to installthe mast nut (4). This is an alternative tothe torque multiplier (2). Ensure the correct

type 1.25 inch (31.7 mm) socket is used.The socket must be capable of a minimumof 1000 foot-pounds (1360 Nm) torque.

23. Install the torque multiplier (2) and support (1) onthe upper plate assembly (8).

24. Torque the mast nut (4) on the mast.

25. Tighten the bolts (6, Figure 62-41) on the lowercone (4). Do the steps that follow:

a. It is very important that you follow the correcttorque sequence (Figure 62-41, Detail D) when youtighten the bolts (6). In sequence, tighten all the boltsto 30 inch-pounds (3.4 Nm). Do the sequence againuntil the bolts do not turn at 30 inch-pounds (3.4 Nm)of torque.

b. Measure the space between the lower cone(4) and the lower cone seat (2) at each bolt location.The measurements must agree to within 0.010 inch(0.25 mm) of each other.

c. Tighten the lower cone bolts (6) in incrementsof 20 inch-pounds (2.3 Nm) in the numbered sequenceshown in Figure 62-41, Detail D, until 105 inch-pounds(11.9 Nm) is reached.

d. Measure the space between the lower cone(4) and the lower cone seat (2) at each bolt location.The measurements must be within 0.010 inch(0.25 mm) of each other.

26. Safety the bolts (6) in pairs with lockwire (C-405)or safety cable (C-152) and ferrule (C-153), as shownin Figure 62-41, Detail D.

27. Ensure the mast nut (4, Figure 62-31) torque iscorrect. If the torque is not correct, tighten the mastnut .

28. Remove the torque multiplier (2) and support (1).

29. Install the lock (7) and attach with the washers (6)and the bolts (5) . Safety the bolts with lockwire(C-405) or safety cable (C-152) and ferrule (C-153).

30. Attach the pitch links (16, Figure 62-33) to thepitch horn (17) with the bolts (10), washers (12),floating bushings (11), and nuts (18) . Install thecotter pin (19). Refer to Figure 62-32, Detail B forappropriate floating bushing configuration.

T

T

T

T

BHT-407-MM-6


NOTE

For flight operations with the Frahmdamper and cover removed, refer toTB 407-03-51.

NOTE

If applicable, do not install the Frahmassembly (2, Figure 62-17) and the cover(1) at this time. This will make it easy for thespecial inspection torque checks(Chapter 5).

31. If the Frahm assembly will not be installed at thistime, attach the washers (26, Figure 62-33) and thenuts (25) to secure the upper hub plate (6) to theelastomeric lead-lag damper (8). Refer toFigure 62-33, Detail A, and Note 6.

32. Install the main rotor blades on the main rotor hubassembly (paragraph 62-48).

33. Install RADS equipment. Do a ground run and onInitial Mode, work the main rotor track and balancevibrations (Chapter 18).

34. When you are satisfied with the main rotorvibration levels in Initial Mode, do the specialinspection torque checks (Chapter 5).

35. If applicable, remove the hardware installed instep 31 and install the Frahm assembly and cover(paragraph 62-57).

36. Continue to work main rotor vibrations in FlightMode (Chapter 18). When you are satisfied with themain rotor vibration levels, do the special inspectionstorque checks (Chapter 5).

NOTE

Ensure the passageway in the lower conesplit (Figure 62-41, Detail C and Detail E) isopen.

NOTE

If a faster cure time is necessary, sealant(C-158) can be used as an alternative tosealant (C-308), where indicated.

37. Apply sealant (C-308) or sealant (C-158), asfollows:

a. Apply sealant (C-308) or sealant (C-158) inthe gap between the lower cone (4, Figure 62-41) andthe lower cone seat (2).

b. Apply sealant (C-308) or sealant (C-158) inthe bore and to the upper ends of the bolts (6) thatattach the lower cone (4) to the lower cone seat (2).

c. Apply sealant (C-308) or sealant (C-158)between the lower cone (4) and the mast (3), asshown in Figure 62-41, Detail D.

d. Apply sealant (C-308) or sealant (C-158)around the mating lines of the mast nut (1,Figure 62-33), upper cone (2), and upper hub plate(6). Cover the upper cone completely.

38. Apply a layer of corrosion preventive compound(C-101) on the exposed bolt heads, threads, and nuts.

62-63. MAIN ROTOR HUB ASSEMBLY —(S/N 53000 THROUGH 53066POST TB 407-99-16 AND S/N 53067THROUGH 53631) — INSTALLATION


NUMBER NOMENCLATURE

407-210-001-101 Hub Support

407-210-002-101 Support


Clevis





Workaid Hub Assembly Alignment

NOTE:


1

1

BHT-407-MM-6





CAUTION


4. Clean the bolts (5, Figure 62-31), washers (6),and lock (7) with drycleaning solvent (C-304). Ensurethat there is no oil, grease, or corrosion preventivecompound on the bolts, washers, and lock.

5. Clean the mast nut lock bolt threaded holes in theupper plate assembly (8).

6. Ensure that the lower cone (7, Figure 62-42) redindex mark is correct, as follows:


b. Align the cone split at the 12 o’clock position.The red index mark should be at the 11 o’clockposition as shown in Detail A.


7. Install the lower cone (7) on the mast (6) with thebevelled side up.


MATERIALS REQUIRED

NUMBER NOMENCLATURE



C-152 Safety Cable

C-153 Ferrule

C-158 Sealant




C-308 Sealant

C-405 Lockwire

C-447 Lockwire

C-561 Grease

407-010-119-101 Peel Shims

NOTES:



1

1

2

1

2

BHT-407-MM-6


Figure 62-42. Main Rotor Hub Center Cone Set, Lower Seat, and Lower Cone (S/N 53000 through 53066 Post TB 407-99-16 and S/N 53067 through 53631) (Sheet 1 of 7)

407MM 62 0072a

2

7

1

ADETAIL


RED INDEX MARKAT 11 O'CLOCK


5

ASEE DETAIL

3

4

4

KSEE DETAIL

6

J

J

2 8

8 SEE DETAILS B, D AND G

1 7

BHT-407-MM-6



407MM_62_0072b

BDETAIL(CALCULATION OF FIRST REQUIRED SHIM)

C-CSECTION

6

C C

MAST SPLINESNOT SHOWNFOR CLARITY

CENTERCONE SET

MAST

CONES PLACEDTOGETHER

TAKE MEASUREMENT INCENTER OF CONE SET GAP

8

FIRST SHIMREQUIRED

TOTAL GAP2 =

BHT-407-MM-6



407MM_62_0072c

DDETAIL(CALCULATION OF SECOND REQUIRED SHIM)

6

E E

MAST

GAP TOMEASURE

TAKEMEASUREMENT INCENTER OF CONE

SET GAP

8

MAST SPLINESNOT SHOWNFOR CLARITY

F

F

CONE SET

9 (FIRST INSTALLED SHIM)

E-ESECTION

9

LOCKWIRE

8

6

F-FSECTION

MEASURED GAP - 0.003 IN. (0.076 mm) =SECOND SHIM REQUIRED

2

1

1

2

BHT-407-MM-6



407MM_62_0072d

GDETAIL

I

I

80.032 IN. (0.813 mm)LOCKWIRE (C-405)(TWO WRAPS)

6

HUB ASSEMBLYALIGNMENT WORK AID(REF FIGURE 62-44)

MASTER SPLINE

HVIEW

SHIM

MASTERSPLINE

SHIMCONE SET

I-ISECTION

MAST

LOCKWIRE

SHIM

CONE SET

MAST

3

5

4

3

5

31

H

BHT-407-MM-6



BHT-407-MM-6



407MM 62 0072f c01

3

6

9

2

1

5

410

8

7

TORQUE SEQUENCE

C RED BLADE AND MASTER TOOTHL

1.2.3.4.5.6.

Lower plateLower cone seatBoltWasherNutMast

MDETAIL

Lower cone7.

1 10THROUGH

Center cone set8.Shims (407-010-119-101)9.

12

11

Upper cone10.

GREASE (C-561)


LOCKWIRE (C-405)

SEALANT (C-308)

85 TO 105 IN-LBS(9.6 TO 11.9 Nm)


5


3

2

1

BHT-407-MM-6



407MM_62_0072g_c01

NOTES

Do not apply grease (C-561) on the mast in the area of the lower cone or to the Teflon fabric of the lowercone.

Make sure that the safety wire pigtails are properly tucked in each cavity.

Apply a thin layer of grease (C-561) to the outside (bevelled) surface of the lower cone.

Apply corrosion preventive compound (C-104) on the shank of the bolts (3) and on the washers (4).Do not apply corrosion preventive compound (C-104) to the bolt threads.

Apply a thin layer of grease (C-561) to the entire surface of the upper cone as well as the matingconical surface of the upper hub plate and the mating surface of the mast nut.

The cone split must remain open after installation is complete to allow the moisture to drain.

Even though there are provisions for safetying the heads of the bolts (3), no lockwire is needed.

Apply a coating of corrosion preventive compound (C-101) to the exposed bolt heads, threads and nutsafter installation.

The final measurements must be within 0.010 inch (0.25 mm) of each other.

Two wraps of 0.040 inch (1.016 mm) lockwire (C-447) are used in this temporary installation to ensure afirm contact of the cone set on the mast. In addition to the safety wire, a "C" clamp may also be used tomake sure that no gaps exist as directed in note .

Make sure no gaps exist between the cone set halves and the mast.

Shims are to be installed at 90° to the master spline and in line with the valley of two splines.

Apply a thin layer of grease (C-561) to the mast external surface in the area between the arrows and to theinside diameter of the center cone set. Do not apply grease (C-561) to the mast nut threads.

1

2

3

4

5

6

7

8

9

10

11

12

13

1

Apply sealant (C-308 or C-158) as shown and make sure the sealant completely covers the mastjournal under the lower cone (7).

Apply sealant (C-308 or C-158) as shown.

An overlap of 0.10 inch (2.54 mm) on the adjacent radius is permitted.

14

15

16

BHT-407-MM-6


CAUTION

DO NOT APPLY THIXOGREASE (C-561)AND CORROSION PREVENTATIVECOMPOUND (C-101 AND C-104) TO THEMETALLIC BEARINGS, ELASTOMERICBEARINGS, SEALS, TEFLON, ANDTEFLON COATED PARTS.THIXOGREASE (C-561) ANDCORROSION PREVENTATIVECOMPOUND (C-101 AND C-104) CAUSEDAMAGE TO THE METALLIC BEARINGS,SEALS, TEFLON, AND THE TEFLONCOATED PARTS.

8. Use aliphatic naphtha (C-305) and thoroughlyclean the mast (6) and the center cone set (8) toremove all corrosion preventive compound.

9. Install the center cone set (8) on the mast andhold in place by hand (Figure 62-42, Sheet 2, DetailB). Close the gap on one side of the center cone setas shown.

10. Measure and calculate the thickness of the firstrequired shim as follows:

NOTE

The intent of TB 407-03-48 has beenincorporated in the following steps to shimthe center cone set (8).

a. Using a vernier caliper, measure theremaining gap. Take the measurement at the center ofthe gap.

b. Divide the dimension obtained in step a bytwo. This is the thickness of the first required shim.

NOTE

Each shim 407-010-119-101 has 0.003 inch(0.076 mm) laminates.

c. Peel the shim to the closest dimensioncalculated in step b. For example, if the calculatedshim thickness required is 0.127 inch (3.226 mm), peelshim to obtain this dimension ±0.003 inch(±0.076 mm).

11. Measure the thickness of the second requiredshim as follows:

CAUTION

IT IS IMPORTANT TO PERFORM THEFOLLOWING STEPS TO ENSURE THECORRECT AMOUNT OF SHIMS AREINSTALLED. THE SUCCESS OF THISINSTALLATION IS DIRECTLY RELATEDTO THE REQUIRED SHIMMEASUREMENTS AND INSTALLATION.IF THE SHIM THICKNESS ISINCORRECT, THE MAIN ROTOR HUBASSEMBLY MAY “SHIFT” ON THE MAST.

a. Temporarily install the center cone set (8) onthe mast (6) with two wraps of 0.040 inch (1.016 mm)lockwire (C-447) (Figure 62-42, Sheet 3, Detail D).

NOTE

The 0.040 inch (1.016 mm) lockwire(C-447) is used in the following step only toensure that the center cone set (8) is firmlyin contact with the mast (6) and that nogaps exist. It may also be required to use a“C” clamp to ensure that no gaps existbetween the mast and the center cone set.

b. Install the first shim (9) in one split, as shownin (Figure 62-42, Sheet 3). Make sure the two centercone set (8) halves are well in contact with the firstinstalled shim and that they remain in firm contact withthe mast (6).

c. Use a vernier caliper and measure the gapbetween the two center cone set (8) halves in thecenter of the gap.

d. Record the dimension obtained in step c, andsubtract this number by 0.003 inch (0.076 mm). Thisnumber is the maximum second shim (9) amount to beinstalled. The intent is to have a minimum loose fit ofthe second shim of 0.003 inch (0.076 mm). Forexample, if the dimension measured in step c is 0.128inch (3.251 mm), the second required shim thicknesswill be 0.125 inch (3.175 mm). Since the shim has0.003 inch (0.076 mm) laminates, the required shimwill be peeled to approximately 0.123 inch (3.124 mm).If the dimension measured is 0.120 inch (3.048 mm),

BHT-407-MM-6


the required shim dimension is 0.117 inch (2.972 mm).In this case, the shim would need to be peeled toapproximately 0.117 inch (2.972 mm).

e. Temporarily install the second required shim(9) in the remaining gap to verify the fit. The shimshould be slightly loose (0.003 inch (0.076 mm)) in thegap and the center cone set (8) should be in firmcontact with the mast (6). Make sure that no gap existsbetween the center cone set and the mast.

f. Remove the center cone set (8) and the shims(9) from the mast (6).

12. Apply a thin layer of grease (C-561) to the insidediameter of the center cone set (8) and associatedmating surface of the mast. Also apply a thin layer tothe mast external surface, as shown between thearrows in Figure 62-42, Sheet 5, View J-J. Install thecenter cone set on the mast (6) with two shims (9).The two shims or the cone set split line center axisshould be at 90° to the master spline and in line withthe valley of two splines.

13. Make sure that the cone set (8) and the shims (9)are firmly attached to the mast (6) with two singlewraps of 0.032 inch (0.813 mm) lockwire (C-405) andthat no gap exists between the cone set and the mast,as shown in Figure 62-42, Sheet 4.

CAUTION

MAKE SURE THE LOCKWIRE “PIGTAIL”DOES NOT PROTRUDE FROM THECENTER CONE SET (8) GAPS. IF THESAFETY WIRE “PIGTAIL” PROTRUDESFROM THE GAPS, DAMAGE TO THELOWER CONE SEAT (2) MAY OCCURDURING THE NEXT MAIN ROTOR HUBASSEMBLY REMOVAL.

14. Bend the two lockwire twisted ends(Figure 62-42, Sheet 4) and tuck the “pigtails”.

15. After the final center cone set (8) installation,ensure that the center cone set and shims (9) arefirmly attached to the mast (6) and that they do notmove in any direction with light hand pressure. If thecenter cone set is loose on the mast, redo theshimming.

NOTE

The use of the main rotor hub assembly-alignment workaid (Figure 62-44) isoptional but recommended to avoid contactof the lower cone set with the mast as thehub assembly is lowered on the mast.

Install the main rotor hub assembly-alignment workaid on the mast nut threads.

16. Use a brush and apply a thin layer ofgrease (C-561) to the outer surface of the center coneset (8, Figure 62-42).






18. Lift the main rotor hub assembly (24,Figure 62-33) and move it above the mast (13).

19. Align the master spline of the main rotor hubassembly (24) with the master spline of the mast (13).

NOTE

Loosening the hub through the bolts (23) ispermitted if restriction is encountered whilelowering the main rotor hub assembly onthe mast. Torque the nuts (38) once theassembly sits on the center cone set(BHT-407-CR&O, Chapter 62).

NOTE

Avoid contact of the main rotor hubassembly (24) with the center cone set (14)to prevent cone set displacement. If yoususpect that this has occurred, lift the mainrotor hub assembly and repeat step 9through step 16.

20. Slowly lower the main rotor hub assembly (24) tothe mast (13). While you lower it, hold the lower cone

T

BHT-407-MM-6


seat and mast stable so that the main rotor hubassembly does not move and contact the center coneset (14) until the main rotor hub assembly sits on thecenter cone set.

21. Remove the strap assemblies (2, Figure 62-45)from the hub upper plate (6). Remove the main rotorhub assembly alignment workaid.

22. Apply a thin layer of corrosion preventivecompound (C-104) on the grip portion of the bolts (3,Figure 62-42) and on the washers (4). Do not let thecorrosion preventive compound (C-104) get on thethreaded portion of the bolts. Remove the excesscorrosion preventive compound (C-104) with a cleancloth.

CAUTION

ENSURE THAT THERE IS NOGREASE (C-561) ON THE LINER OF THELOWER CONE (7). GREASE CAUSESDAMAGE TO THE LINER.

23. Apply a thin layer of grease (C-561) to the outside(bevelled) surface of the lower cone (7).

NOTE

Ensure the red index mark on the lowercone (7) is aligned with the center line ofthe red blade (Figure 62-42, Detail M).

24. Use the bolts (3), washers (4), and nuts (5) toinstall the lower cone (7). Do not tighten nuts at thistime.

CAUTION



26. Put the mast nut (4, Figure 62-31) on the mast.

NOTE

A 3/4-inch (19 mm) drive torque wrench (9)with a minimum 1000 foot-pound(1360 Nm) capacity can be used to installthe mast nut (4). This is an alternative tothe torque multiplier (2) used with thesupport 407-210-002-101 (1). Ensure thecorrect type 1.25 inch (31.7 mm) socket isused. The socket must be capable of aminimum of 1000 foot-pounds (1360 Nm)torque.

27. Install the torque multiplier (2) and the support (1)on the upper plate assembly (8).


NOTE

It is very important that the correct torquesequence is followed when tightening thenuts (5, Figure 62-42). Even though thereare provisions for safetying the heads of thebolts (3), no lockwire or safety cable isneeded.

29. Tighten the nuts (5, Figure 62-42) on the lowercone (7), as follows:

a. Tighten the nuts (5) in sequence to30 inch-pounds (3.4 Nm). Do the sequence again untilthe nuts do not turn at 30 inch-pounds (3.4 Nm) oftorque.

b. Continue to tighten the lower cone nuts (5) inincrements of 20 inch-pounds (2.3 Nm) in numberedsequence, as shown in Figure 62-42, Detail M. Do thesequence again for every torque increment until thenuts stop turning. Follow this procedure until you reachthe final torque .

30. Using a feeler gauge, measure the spacebetween the lower cone (7) and the lower cone seat(2) at each bolt location. The measurements must be

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BHT-407-MM-6


within 0.010 inch (0.25 mm) of each other(Figure 62-42, Detail K).

31. Ensure the mast nut (4, Figure 62-31) torqueis correct. If torque is not correct, reapply 650 to 700foot-pounds (881 to 941 Nm) of torque.

32. Remove the torque multiplier (2) and the support407-210-002-101 (1).

33. Install the lock (7) and attach with the washers (6)and bolts (5).

34. Tighten bolts (5) and safety with lockwire(C-405) or safety cable (C-152) and ferrule (C-153).

NOTE


If applicable, do not install the Frahmassembly (2, Figure 62-17) and thecover (1) at this time. This will make it easyfor the special inspection torque checks(Chapter 5).

35. If the Frahm assembly will not be installed at thistime, attach the washers (26, Figure 62-33) and thenuts (25) to secure the upper hub plate (6) to theelastomeric lead-lag damper (8). Refer toFigure 62-33, Detail A and Note 6.

36. Attach the pitch links (16) to the pitch horns (17)with the bolts (10), floating bushing (11), washer (12),and nuts (18) . Refer to Figure 62-33, Detail B1 orDetail B2, for the appropriate floating bushing (11)configuration.

37. Safety the nuts (18) with the cotter pins (19).




41. If applicable, remove the hardware installed instep 35, and install the Frahm assembly and the cover(paragraph 62-57).

42. Continue to work main rotor vibrations in FlightMode (Chapter 18). When you are satisfied with themain rotor vibration levels, do the special inspectionstorque checks (Chapter 5).

NOTE

Ensure the passageway in the lower conesplit (Figure 62-42, Detail M) is open.

NOTE



a. Apply sealant (C-308) or sealant (C-158) inthe gap between the lower cone (7, Figure 62-42,Detail K) and the lower cone seat (2).

b. Apply a layer of sealant (C-308) or sealant(C-158) between the lower cone (7) and the mast (6),as shown in Figure 62-42, Detail L.

c. Apply sealant (C-308) or sealant (C-158)around the mating lines of the mast nut (1,Figure 62-33, Detail G), upper cone (2) and upperplate (6). Cover the upper cone completely.


62-64. MAIN ROTOR HUB ASSEMBLY —(S/N 53000 THROUGH 53631POST TB 407-05-66 AND S/N 53632AND SUBSEQUENT) — INSTALLATION

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NUMBER NOMENCLATURE

407-210-001-101 Hub Support

407-210-002-101 Support

BHT-407-MM-6





CAUTION


4. Clean the bolts (5, Figure 62-32), washers (6),lock (7), and retainer (8) with drycleaning solvent(C-304). Ensure that there is no oil, grease, orcorrosion preventive compound on the bolts, washers,lock, and retainer.

5. Clean the mast nut lock bolt threaded holes in theupper plate assembly (9).

6. Ensure that the lower cone (7, Figure 62-43) redindex mark is correct, as follows:


Clevis





Workaid Hub Assembly Alignment

NOTE:



MATERIALS REQUIRED

NUMBER NOMENCLATURE



C-152 Safety Cable

C-153 Ferrule

C-158 Sealant



C-308 Sealant

C-405 Lockwire

C-561 Grease

SPECIAL TOOLS REQUIRED (Cont)

NUMBER NOMENCLATURE

1

1

1

1

2

NOTES:





NUMBER NOMENCLATURE

1

2

BHT-407-MM-6


Figure 62-43. Integral Mast Center Cone and Main Rotor Hub Lower Seat and Lower Cone(S/N 53000 through 53631 Post TB 407-05-66 and S/N 53632 and Subsequent) (Sheet 1 of 3)

407MM_62_0036a

2

7

1

ADETAIL


RED INDEX MARKAT 11 O'CLOCK


5

ASEE DETAIL

3

4

4

CSEE DETAIL

6

B

B

2 2

1 3 4

BHT-407-MM-6



BHT-407-MM-6



407MM_62_0036c_c01

3

6

9

2

15

410

8

7

TORQUE SEQUENCE

C RED BLADE AND MASTER TOOTHL

1.2.3.4.5.6.

Lower plateLower cone seatBoltWasherNutMast

EDETAIL

Lower cone7.

1 10THROUGH

Upper cone8.Integral mast center cone9.

NOTES

Apply corrosion preventive compound (C-104) on the shank of the bolts (3) and on the washers (4).

Do not apply grease (C-561) on the mast in the area of the lower cone or to the Teflon fabric

Apply a thin layer of grease (C-561) to the outside (bevelled) surface of the lower cone.

The final measurements must be within 0.010 inch (0.25 mm) of each other.

Even though there are provisions for safetying the heads of the bolts (3), no lockwire or safety cable isneeded.The cone split must remain open after installation is complete to allow the moisture to drain.

Apply a thin layer of grease (C-561) to the mast external surface in the area between the arrows.Do not apply grease to the mast nut threads.

of the lower cone.

Apply a thin layer of grease (C-561) to the entire surface of the upper cone as well as the mating conical

7

8

GREASE (C-561)



SEALANT (C-308)

85 TO 105 IN-LBS(9.6 TO 11.9 Nm)

Apply a coating of corrosion preventive compound (C-101) to the exposed bolt heads, threads and nutsafter installation.

1

2

3

4

5

6

7

8

9


5

Do not apply corrosion preventive compound to the bolt threads.

An overlap of 0.10 inch (2.54 mm) on the adjacent radius is permitted.

Apply sealant (C-308 or C-158) as shown.

10

11

12

Apply sealant (C-308 or C-158) as shown and make sure the sealant completely covers the mastjournal under the lower cone (7).

GREASE (C-561)

3

surface of the upper hub plate and mating surface of the mast nut.

2

1

BHT-407-MM-6



b. Align the cone split at the 12 o’clock position.The red index mark should be at the 11 o’clockposition, as shown in Detail A.


7. Install the lower cone (7) on the mast (6) withbevelled side up.

CAUTION

DO NOT APPLY GREASE (C-561) ANDCORROSION PREVENTATIVECOMPOUND (C101 AND C-104) TO THEMETALLIC BEARINGS, ELASTOMERICBEARINGS, SEALS, TEFLON, ANDTEFLON COATED PARTS. GREASE ANDCORROSION PREVENTIVE COMPOUNDCAUSE DAMAGE TO THE METALLICBEARINGS, SEALS, TEFLON, AND THETEFLON COATED PARTS.

8. Use a brush to apply a thin layer ofgrease (C-561) to the mast (6) outside diameter, asshown in Figure 62-43 View B-B.

NOTE

The use of the main rotor hub assemblyalignment workaid (Figure 62-44) isoptional but recommended to avoid contactof the lower cone seat with the mast as thehub assembly is lowered on the mast.

9. Install the main rotor hub assembly alignmentworkaid (Figure 62-44) on the mast nut threads.






11. Lift the main rotor hub assembly (24,Figure 62-33) and move it above the mast (13).

12. Align the master spline of the main rotor hubassembly (24) with the master spline of the mast (13).

NOTE

Loosening the hub through the bolts (23) ispermitted if restriction is encountered whilelowering the main rotor hub assembly onthe mast. Torque the nuts (38) once theassembly sits on the integral mast centercone (BHT-407-CR&O, Chapter 62).

13. Slowly lower the main rotor hub assembly (24) tothe mast (13) until the hub assembly sits on theintegral mast center cone (9, Figure 62-43).

14. Remove the strap assemblies (2, Figure 62-45)from the hub upper plate (6). Remove the main rotorhub assembly alignment workaid (Figure 62-44).

15. Apply a thin layer of corrosion preventivecompound (C-104) on the grip portion of bolts (3,Figure 62-43) and on the washers (4). Do not let thecorrosion preventive compound get on the threadedportion of the bolts. Remove the excess corrosionpreventive compound with a clean cloth.

CAUTION

ENSURE THAT THERE IS NOGREASE (C-561) ON THE LINER OF THELOWER CONE (7). GREASE CAUSESDAMAGE TO THE LINER.

16. Apply a thin layer of grease (C-561) to the outside(bevelled) surface of the lower cone (7).

NOTE

Ensure the red index mark on the lowercone (7) is aligned with the center line ofthe red blade (Figure 62-43, Detail E).

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BHT-407-MM-6


Figure 62-44. Main Rotor Hub Assembly — Alignment Workaid407MM_62_0081_c01

A

MAST

NOTES

This workaid can be locally manufactured or procured throughParavion Technology under part number T0001.

Paravion Technology Inc.2001 Airway avenueFort Collins, CO. 80524, USA.Phone: (970) 224-3898Fax:E-Mail: [email protected]

(970) 224-3899

MAIN ROTOR HUBASSEMBLY ALIGNMENTWORKAID NO.1

A

7.500 TO 8.000 IN.

2.210 IN.(56.13 mm)

0.430 IN.(10.92 mm)

0.750 IN.(19.05 mm)

(190.50 TO 203.20 mm)

A-ASECTION

2.125-16UNJ-3BTHREADS 0.43 IN.(10.92 mm) DEEP

1.250 IN.(31.75 mm)

DIA.

2.490 IN.(63.25 mm)

DIA.

CHAMFER 0.25 IN. (6.35 mm) X 45°

MATERIAL: ALUMINUM 6061-T6

2

2

Inside diameter to outside diameter concentricity to be within 0.002 inch (0.05 mm).

1

1

3. All dimension tolerances are ± 0.010 inch (0.25 mm).

BHT-407-MM-6


Figure 62-45. Hub Sling and Support Tool407MM_62_0025_c01

DETAIL A

ASEE DETAIL

6

1

3

2

5

2

4

7 6

NOTE

1

1 Make sure that each strap assembly (2) is installed against theelastomeric lead-lag damper (4).

8

HoistStrap assemblyMain rotor hub assemblyElastomeric lead-lag damperHub supportHub upper plateMastClevis

1.2.3.4.5.6.7.8.

BHT-407-MM-6


17. Use the bolts (3), washers (4), and nuts (5) toinstall the lower cone (7). Do not tighten the nuts atthis time.

CAUTION



19. Put the mast nut (4, Figure 62-32) on the mast.

NOTE

A 3/4-inch (19 mm) drive torque wrench (9)with a minimum 1000 foot-pound (1360Nm) capacity can be used to install themast nut (4). This is an alternative to thetorque multiplier (2) used with the support407-210-002-101 (1). Ensure the correcttype 1.25 inch (31.7 mm) socket is used.The socket must be capable of a minimumof 1000 foot-pounds (1360 Nm) torque.

20. Install the torque multiplier (2) and the support (1)on the upper plate assembly (8).


NOTE

It is very important that the correct torquesequence is followed when tightening thenuts (5, Figure 62-43). Even though thereare provisions for safetying the heads of thebolts (3), no lockwire or safety cable isneeded.

22. Tighten the nuts (5, Figure 62-43) on the lowercone (7), as follows:

a. Tighten the nuts (5) in sequence to30 inch-pounds (3.4 Nm). Do the sequence again untilthe nuts do not turn at 30 inch-pounds (3.4 Nm) oftorque.

b. Continue to tighten the lower cone nuts (5) in20 inch-pound (2.3 Nm) increments in numberedsequence, as shown in Figure 62-43, Detail E. Do thesequence again for every torque increment until thenuts stop turning. Follow this procedure until you reachthe final torque .

23. Using a feeler gauge, measure the spacebetween the lower cone (7) and the lower cone seat(2) at each bolt location. The measurements must bewithin 0.010 inch (0.25 mm) of each other(Figure 62-43, Detail C).

24. Ensure the mast nut (4, Figure 62-32) torqueis correct. If torque is not correct, reapply 750 to800 foot-pounds (1017 to 1085 Nm) of torque.

25. Remove the torque multiplier (2) and the support407-210-002-101 (1).

26. Install the lock (7) and attach with the retainer (8),as follows:

a. Apply a thin layer of corrosion preventivecompound (C-104) on the grip portion of bolts (5) andthe washers (6).

b. Position the retainer (8) over the threadedholes on the upper plate assembly (9).

c. Install hand-tight the bolt (5) and washer (6)on the thicker side hole of the retainer (8).

NOTE

Install the lock (7) so that the related hole inthe retainer (8) is positioned within thetangs of lock. Do not allow any portion ofthe related hole in the retainer to bepositioned outside of the lock tangs.

d. Slide the lock (7) between the mast nut (4)and the retainer (8) until the teeth properly engage onboth the retainer and lock.

e. Install the remaining bolt (5) and washer (6) tosecure the lock (7) and retainer (8) to the upper plateassembly (9).

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BHT-407-MM-6


f. Tighten the bolts (5) and safety withlockwire (C-405) or safety cable (C-152) and ferrule(C-153).

NOTE


NOTE

If applicable, do not install the Frahmassembly (2, Figure 62-17) and the cover(1) at this time. This will make it easy for thespecial inspection torque checks(Chapter 5).

27. If the Frahm assembly will not be installed at thistime, attach the washers (26, Figure 62-33) and thenuts (25) to secure the upper hub plate (6) to theelastomeric lead-lag damper (8). Refer toFigure 62-33, Detail A, and Note 6.

28. Attach the pitch links (16) to the pitch horns (17)with the bolts (10), floating bushing (11), washer (12),and nuts (18) . Refer to Figure 62-33, Detail B1 orDetail B2, for the appropriate floating bushing (11)configuration.

29. Safety the nuts (18) with the cotter pins (19).




33. If applicable, remove the hardware installed instep 27, and install the Frahm assembly and the cover(paragraph 62-57).

34. Continue to work main rotor vibrations in FlightMode (Chapter 18). When you are satisfied with the

main rotor vibration levels, do the special inspectionstorque checks (Chapter 5).

NOTE

Ensure the passageway in the lower conesplit (Figure 62-43, Detail E) is open.

NOTE



a. Apply sealant (C-308) or sealant (C-158) inthe gap between lower cone (7, Figure 62-43,Detail C) and lower cone seat (2).

b. Apply sealant (C-308) or sealant (C-158) inthe space between lower cone (7) and mast (6), asshown in Figure 62-43, Detail D.

c. Apply sealant (C-308) or sealant (C-158)around the mating lines of the mast nut (1,Figure 62-33, Detail D), upper cone (2), and upper hubplate (6). Cover the upper cone completely.

d. Apply a bead of sealant (C-308) or sealant(C-158) to the mating edges of the bolts (3), nuts (5),and lower cone seat (2), as shown in Figure 62-43.


62-65. MAIN ROTOR SYSTEM — UP ANDDOWN STOP ASSEMBLIES

The up and down stop assemblies (2 and 10,Figure 62-46) are attached to the upper and lowerplate assemblies (1 and 9) of the main rotor hubassembly. They protect the composite material of theyoke (7, Figure 62-33) from too much flex. Theremoval and installation procedures for the up anddown stop assemblies are different because of theblade droop when the rotor is stopped.

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BHT-407-MM-6


Figure 62-46. Up and Down Stop Assemblies — Removal and Installation

407MM_62_0031_c02

SEE DETAIL A

SEE DETAIL B

DETAIL B

DETAIL A

12

13

12 3

SEE DETAIL C

9 10

11

CSEE DETAIL

DETAIL C

4

5

6

8

7

1. Upper plate assembly2. Up stop assembly3. Pitch horn4. Stop lockplate5. Jam nut6. Stop stud7. Cotter pin8. Stop plug9. Lower plate assembly

10. Down stop assembly11. Pitch horn12. Sling13. Main rotor blade

UP STOP AJUSTMENT

DOWN STOP AJUSTMENT

14. Hoist

14

STA 108.25APPROXIMATE CENTEROF GRAVITY (CG) OFTHE BLADE

0.490 TO 0.510 IN.(12.45 TO 12.95 mm)

0.615 TO 0.635 IN.(15.63 TO 16.12 mm)

250 TO 300 IN-LBS(28.25 TO 33.90 Nm)


4

4

0.490 TO 0.510 IN.(12.45 TO 12.95 mm)

0.615 TO 0.635 IN.(15.63 TO 16.12 mm)

(TYPICAL 4 PLACES)

(TYPICAL 4 PLACES)

BHT-407-MM-6


62-66. UP AND DOWN STOP ASSEMBLIES —REMOVAL


NOTE

The main rotor blade (13, Figure 62-46)does not need to be lifted to remove the upstop assembly (2).

2. To remove the down stop assembly (10), do thesteps that follow. If you remove the up stop assembly(2), go to step 3.

CAUTION

ENSURE THAT THE HOIST IS OVER THECENTER OF GRAVITY OF THE MAINROTOR BLADE. THE CENTER OFGRAVITY FOR THE MAIN ROTOR BLADEIS SHOWN IN FIGURE 62-46.

a. Attach the sling (12) (T101626) to the hoist.Put the hoist directly over the center of gravity of themain rotor blade (13). Attach the sling (T101626)straps around the main rotor blade.

b. Lift the main rotor blade (13) until the up stop(2) touches the pitch horn (3).

3. Remove and discard the cotter pins (7) that holdthe stop plug (8) on the stop stud (6). Remove the stopplug.

4. Make the tabs on the stop lockplate (4) straight.

5. Loosen the jam nut (5) and remove the stop stud(6). Discard the stop lockplate (4).

6. If the down stop assembly (10) is to be installedimmediately, leave the main rotor blade (13) in the upposition with the sling (12) (T101626) and thehoist (14).

7. If the down stop assembly (10) is not to beinstalled immediately, remove the main rotor blade(13) from the helicopter (paragraph 62-12) until thedown stop assembly is installed.

62-67. UP AND DOWN STOP ASSEMBLIES —INSPECTION AND REPAIR

NOTE

For damage limits on stop plug and droopstop stud, refer to the BHT-407-CR&O.

1. Clean the stop plug (8, Figure 62-46) with a clothdampened with drycleaning solvent (C-304).

2. Examine the stop plug (8) for wear and damage.If you find cracks or excessive wear, replace the stopplug.

3. Permitted scratches and nicks on the stop plug(8) can be repaired with 400 grit abrasive paper(C-423). Remove all marks from the repair with crocuscloth (C-500).

4. Clean the stop stud (6) with a cloth wet withdrycleaning solvent (C-304).

5. Examine the stop stud (6) for cracks and threaddamage. If you find cracks, replace the stop stud.


NUMBER NOMENCLATURE

T101626 Sling


MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-108 LHE Cadmium Plating Solution



C-500 Crocus Cloth

BHT-407-MM-6


6. Permitted mechanical and corrosion damage onthe stop plug (8) can be repaired with 400 grit abrasivepaper (C-423). Remove all marks from the repair withcrocus cloth (C-500).

7. Touch up the finish of the stop stud (6) with LHEcadmium plating solution (C-108).

62-68. UP AND DOWN STOP ASSEMBLIES —INSTALLATION


NOTE

The main rotor blade (13, Figure 62-46)does not need to be lifted to install the upstop assembly (2).

2. To install the down stop assembly (10), do thesteps that follow. If you install the up stop assembly(2), go to step 3.

CAUTION

ENSURE THAT THE HOIST IS OVER THECENTER OF GRAVITY OF THE MAINROTOR BLADE. THE CENTER OFGRAVITY FOR THE MAIN ROTOR BLADEIS SHOWN IN FIGURE 62-46.

a. Attach the sling (12) (T101626) to the hoist(14). Put the hoist directly over the center of gravity ofthe main rotor blade (13). Attach the straps of the sling(T101626) around the main rotor blade.

b. Lift the main rotor blade (13) until the up stopassembly (2) touches the pitch horn (3).

3. Apply a layer of corrosion preventive compound(C-101) to both sides of the new stop lockplate (4).

4. Install the jam nut (5) and the stop lockplate (4)on the stop stud (6).

5. Install the stop stud (6) on the upper or lowerplate assembly (1 or 9). Turn the stop stud in about0.5 inch (12.7 mm).

6. Put the stop plug (8) in the recess of the stop stud(6). Safety the stop plug with new cotter pins (7). Bendthe cotter pin tails around the circumference of thestop stud.

7. Adjust the up and down stop assemblies (2 and10) to the length shown in Figure 62-46, Details A andB. Tighten the jam nut (5) and safety with lockwire(C-405), or safety cable (C-152), and ferrule (C-153),to a tab on the stop lockplate (4).

8. Bend the other tabs on the stop lockplate (4) 90°away from the stop plug (8).

9. Apply a coating of corrosion preventivecompound (C-101) to the exposed threads of the stopstud (6) and jam nut (5).


NUMBER NOMENCLATURE

T101626 Sling


MATERIALS REQUIRED

NUMBER NOMENCLATURE


C-152 Safety Cable

C-153 Ferrule

C-158 Sealant

C-405 Lockwire

NOTES:



1

1

2

1

2 T

407-MM-CH62

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