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MANUAL FASTENING WITH SHORT THREAD POINT DRIVE BOLTS
NOTES:
(A) Reference in this specification to any other document shall be to the latest issue of that document unless specifically stated otherwise.
(B) For definitions and procedures relating to the use of ABP specifications refer to AMCD 01 and ABP 0-0001.
(C) This specification does not necessarily detail all the precautions necessary to meet the requirements of health and safety.
It is the responsibility of the user of this specification to consult and establish appropriate Health and Safety precautions and the method should be operated only by trained personnel.
KEY WORDS:
Fastening Manual Fastening Bolts Point Drive Bolts
ABP 0-1011 Control of Technique Sheets Approved Before Manufacture
ABP 1-4327 Coating of Bolts and Fasteners with Lubricant Prior to Fastening
ABP 4-5141 Application of Sealant for Integral Fuel Tanks
ABP 4-5142 Application of Sealant for General Aircraft Structure
ABR 9-0140 General Purpose Cleaning Solvent
ABP 2-2336 Common Requirements for Bolts, Studs, Nuts and other Fastening Parts
SCOPE
This Specification defines the requirements for the manual installation, and removal, of short thread point drive lead-in radius bolts, assembled with self-locking nuts, when fitted into interference or clearance fit holes.
1. INTRODUCTION
1.1 Use of this process specification for the installation of bolts of the short-thread, point drive or pull-in, lead-in radius type is restricted solely to the fasteners, and the self-locking nuts, which are specified herein:
This specification is applicable to metals, CFRP, metal/CFRP assemblies and thermoplastic* composite.
Note: * This specification shall be limited to bolts installed into AIMS 05-08-001-01 glass reinforced thermoplastic material.
ASNA2532 Self locking, with a spherical joint and a self alignment washer
ASNA2531 Self locking, hexagon, non corrosion resisting steel, counterbored.
ASNA2536 - Hexagonal, self locking, bi hex, shear type.
ASNA2538 - Hexagonal, self locking, ball, bi hex, shear type.
1.2 These bolts are marketed under the registered trade-name “Hi-lite”. The installation of point drive bolts marketed under the trade name of “Hi-lok” is the subject of ABP 2-2074. There are significant differences between these two types of fastener.
1.3 References to NSA, ASNA and ABS fasteners and parts defined in this specification are for drawing / design documentation call up purposes only. Actual part identification may be in accordance with the “Hi-Lite” or Manufacturers proprietary system as indicated in tables 1 and 3, Appendix B. Reference should be made to the appropriate part specification for further information.
1.4 When the drawing specifies provision of a Technique Sheet, as for example for a critical joint, the technique and sequence at assembly shall be agreed between the Airbus UK Design Authority and the Manufacturing function. The Technique Sheet shall be signed by the Airbus UK Design Authority at Issue 1, and all subsequent issues in accordance with ABP 0-1010 unless the drawing states otherwise.
* Note: For joints with slope on collar/nut side higher than 3º, up to the limit in the standard, the impact on the joint performance requires assessment by design.
Spot facing to achieve these requirements is permitted only when called for on the drawing.
1.6 ASNA2026 (-, BV, HK), ASNA2027 (-, BV, HK), ABS0559 (VBV, VHK) and ABS0560 (VBV, VHK) are supplied without lubrication.
ABS0807K, ABS0809 (-,VHK), ABS0810 (-, VHK), ABS0811VHK, ABS0812VHK, ABS0907K, ASNA2026T, ASNA2027T, EN6114 (-, T, V, K, L) and EN6115 (-, T, V, K, L) are supplied with lubrication.
1.7 With bolts and nuts specified in Para 1.1 it should not be necessary in any application for a washer to be fitted. However, the infrequent use of a washer, when essential, is covered by Para 3.1.9.
All equipment and plant shall be approved by the Airbus UK Quality Assurance Authority and operated and maintained to manufacturer’s instructions. The issuing of any supplementary instructions necessary to ensure that the requirements of this specification are met, is the responsibility of the Airbus UK Quality Assurance Authority.
For suppliers, see Appendix A Approved Equipment and Materials
3. PROCEDURE
3.1 Installation
Note 1: Joints/fasteners shall be assembled with sealant to the requirements of ABP 4-5141 for integral fuel tanks/ABP 4-5142 for other applications, unless otherwise specified on the drawing.
3.1.1 Drill and ream, drill ream, countersink or radius and deburr holes in accordance with the Standards stated on the drawing. Where a spot-face has been machined in conformance with the drawing, reinstate the protective treatment in accordance with the master protective scheme specification, unless the drawing specifies otherwise, before final installation of the fastener.
3.1.2 Submit part/component to Inspection function for checking of hole for conformance with the relevant standard (i.e. diameter, countersink or radius, deburring and finish) and spot-face where relevant.
3.1.3 Obtain the bolts as called for on the drawing and check they are the correct grip length before trial installation of two fasteners as detailed in Para 3.1.4 to 3.1.10 inclusive.
3.1.4 Ensure that bores and areas adjacent to holes are free from any contamination, by using clean "Kimwipe" wipers or a clean cloth or wiper moistened with ABR9-0140.
3.1.5 a) Clearance fit applications: -
Prior to inserting the bolt into the hole ensure that sufficient sealant/jointing compound (ref. Para 3.1 Note 1) is applied to the shank and underhead region of the bolt to fill any gaps between the bolt and the hole.
i) conform to any special installation and/or tightening sequences specified on the drawing. The process is not generally applicable when one or both of the components are thin and/or bonded.
ii) ensure that the joint has slave bolts/final fasteners securely clamping the joint on either side of the fastener to be installed.
iii) Prior to driving or pulling the bolts into the holes sealant / jointing compound should be applied to the underhead region of the bolt (ref. Note 1 above Para 3.1.1). In addition where bolts are supplied without lubricant (ref: paragraph 1.6) the shanks should be lubricated in accordance with the requirements of ABP 1-4327.
Boelube 70305 paste in addition to bolt lubrication described in ABP 1-4327 is permitted for use subject to the following limitations:
a) To be used on cadmium plated alloy steel bolts of ½” diameter and above.
b) To be used on bolts with T/D ratio of 2.5 and above –
(T= joint thickness and D =bolt diameter).
c) Lubrication shall be applied to bore and bolt shank only. Any contamination to
surrounding areas and to the bolt thread shall be carefully removed using Airbus
approved cleaning agents and procedures
d) Boelube paste shall only be used where the drawing requires cadmium plated
bolts to be inserted under interference fit conditions through aluminium
containing assemblies.
iv) Where the drawing, fastener type or joint configuration (i.e. stack thickness ≥ 3D) calls for the use of ‘pull-in’ installation procedures reference should be made to the additional requirements specified in Appendix E. In all other cases the bolt should be carefully driven into place using a suitable riveting gun or dolly, taking care to ensure that neither the bolt nor the surface of the part is damaged.
3.1.6 Ensure that the head of the bolt is correctly seated in accordance with ABP2-2336.
3.1.7 Remove all sealant/jointing compound from the bolt threads by wiping with a clean ‘Kimwipe’ tissue moistened with ABR 9-0140 or other approved solvent. See Appendix A.
3.1.8 Check that the bolt protrusion through the joint is within gauging limits as detailed in Appendix D. (Compliance with these gauging instructions will determine whether a bolt with the lead in radius intruded slightly into the holes, shall be accepted). The removal of fastener threads to achieve protrusion tolerances is strictly prohibited.
Bolts of different grip length to those specified by the drawing may be fitted subject to the requirements of Para. 4.2.
3.1.9 Note: with the combinations defined in Para 1.1 there will not normally be any need for washers to be fitted under the nuts unless so specified by the drawing. Indiscriminate use of washers is prohibited but, on isolated occasions when use is essential, allowance shall be made for the thickness of the washer in the grip length to be employed, i.e. the acceptance gauging will be from the front face of the washer. Ensure that any sealing instructions - ABP 4-5141 / ABP 4-5142 as invoked by the drawing - are observed. Assemble the nut called for on the drawing onto the bolt finger tight.
3.1.9.1 A400M requirements. – The following requirements are for installation of fasteners within the Fuel Tank Boundary.
a) Installation of steel washer under a nut (ASNA2531 or ASNA2532).
Sealant shall be applied to the face of the washer that will be in contact with the component. Sealant contamination of the bolt threads and nuts shall be kept to a minimum. No sealant shall be applied to the nuts or where applicable the self-aligning washer. Nuts shall be installed by:
1). Manual process.
2). Using a pneumatic/electronic nut runner up to the contact point of the nut and washer and hand tighten to the torque stated in Appendix C.
3). Using electronic nut runner up to the requirements of Appendix C and Appendix G.
b) Installation of a self aligning nut (ASNA2532) without a steel washer.
Sealant shall be applied to underside of the self-aligning washer. Sealant contamination of the bolt threads and nuts shall be kept to a minimum. No sealant shall be applied to the nuts or where applicable the self-aligning washer. Nuts shall be installed by:
1). Manual process.
2). Using a pneumatic/electronic nut runner up to the contact point of the nut and washer and hand tighten to the torque stated in Appendix C.
3). Using electronic nut runner up to the requirements of Appendix C and Appendix G.
3.1.10 Obtain the approved hand or power tool ensuring that it is set to the correct torque level and where designated, speed limitation for the bolt/nut combination (ref. Appendix C). Where necessary, and provided the fastener geometry allows, restrain the bolt from moving by engaging the hexagon key in the recess and torque tighten the nut. After installation, slightly rotate the power tool in a clockwise direction to ease its removal from the bolt and nut. The bolt thread protrusion beyond the nut shall conform with the requirements of Appendix D. The flushness of countersunk head bolts shall conform to requirements given in the Standard stated on the drawing and in accordance with ABP2-2336.
3.1.11 Remove all exuded sealant/jointing compound using a suitable non-metallic (e.g. Tufnol) tool in accordance with ABP 4-5141 or ABP 4-5142.
3.1.12 At the discretion of the Manufacturing function, either submit the two fastener trial installation to Inspection function for verification of correct grip length/assembly requirements, ref. Para 4.2 before completing the assembly or alternatively Manufacturing function may, at its own responsibility, complete the assembly in accordance with the requirements of Para 3.1.4 to 3.1.11.
3.1.13 Submit completed assembly to Inspection function.
3.1.14 Fasteners rejected by the Inspection function shall be removed in accordance with Para 3.2.
3.1.15 All fasteners shall be re-torque tightened to account for possible joint relaxation as per ABP2-2336. Nuts shall not be slackened off as part of the torque checking procedure.
3.2 Removal and Re-installation Note: Removed interference fit fasteners shall not be re-installed.
3.2.1 Using the correct size hexagon key to prevent rotation of the bolt, unscrew and remove the nut using a spanner or the special ratchet fitted with a socket spanner or a power tool switched to reverse. Note: a hexagon key may not be needed for interference fit bolts.
3.2.2 Remove the bolt from the assembly. For an interference fit bolt use a suitable riveting gun and dolly to move the bolt sufficiently to enable an extractor to be fitted under the bolt head. Withdraw the bolt completely by using the extractor.
3.2.3 Submit the assembly to the Inspection function.
3.2.4 i) when hole and adjacent material have been confirmed as satisfactory, install new bolt(s) and nut(s) in accordance with Para 3.1.
ii) if the Inspection function considers that unsatisfactory features exist, refer to the Airbus UK Design Authority.
4.1 Hole geometries conform to drawing call-up requirements or for high interference fasteners the requirements specified in Appendix E
4.2 When requested by Manufacturing function (see Para 3.1.12), the correct length bolt has been used, by checking and approving the trial fastener installation prior to completing the assembly. (See Paras 4.3 & 4.4 below, and procedure specified in Appendix D).
Note: Where, due to the accumulation of tolerances, the grip length of the bolt called for on the drawing is not correct, Inspection function may allow a substitution without reference back to the Airbus UK Design Authority subject to the following limitations: -
a) That the variation is not more than one grip size.
b) That the requirement of Para 3.1.9 is satisfied.
c) Where this replacement occurs repeatedly on a joint, the Airbus UK Design Authority shall be advised in order that drawing amendment can be considered.
d) No variation of bolt length is permitted for interchangeable parts without Airbus UK Design Authority approval.
4.3 Bolt protrusion is within the gauging dimensions as detailed in Appendix D. This will ensure that a minimum of one thread pitch protrudes beyond the nut and that the fully formed threads of the bolt engage the nut locking element.
Installation with head seated in hard material parts (steel, titanium,
Inconel etc.)
Shear or medium head P (mm)
Shear or medium head P (mm)
Fastener material
Titanium 0,10 0,07
Alloy steel 0,07 0,05
Inconel 0 0
4.6 Holes and adjacent structure (including protective treatment) are free from damage after any fastener removal, and hole sizes are dimensionally correct before replacement fasteners are fitted.
4.7 Repairs to the protective finish conform with drawing and invoked specification requirements.
4.8 Bolt protrusion tolerances in Appendix D are not applicable for Oversize bolts.
1. Drawings call up bolts/nuts by the appropriate Material/In-house Standard. Bolts/nuts may be identified with manufacturers part numbers, ref. tables 1 and 2.
Table 1: Bolt Identification
NOMINAL DIAMETER
DASH No (1/16"Increments)
HEAD TYPE PROPRIETARY PART No Airbus PART No MATERIAL & FINISH
(-3) - (-10)
100° Countersunk Intermediate
HST755 (CF) VL755 (CF) AL755 (CF)
ASNA2026VBV 6Al4V Titanium alloy. IVD aluminium coated. Non-lubricated. Thread end dyed black
Protruding
HST756 (CF) VL756 (CF) AL12 (CF)
AL756 (CF)
ASNA2027VBV
100° Countersunk Intermediate
HST755 (KN) VL755 (KN) AL755 (KN)
ASNA2026VHK 6Al4V Titanium alloy. Resin based aluminium coated. Non-lubricated. Thread end not dyed.
2. BOLT HEAD IDENTIFICATION Bolt identification in the case of ASNA and ABS coded parts will be in accordance with the manufacturers proprietary system as defined in table 2. Bolt head identification for EN6114 and EN6115 parts will be in accordance with EN6114 / EN6115 standards
Table 2. Proprietary ID code for ASNA and ABS bolts
Standard Diameter Code
Proprietary (Basic) Part Number
Diameter Code
ABS0807K (-3 to -8) HSL755 (-6 to -16) ABS0907K (-3 to -8) HSL756 (-6 to -16) ABS0809 ABS0809VHK
(-9 to -16) (-9 to -10)
HPL755
(-18 to -32) (-18 to -20)
ABS0810 ABS0810VHK
(-9 to -16) (-9 to -10)
HPL756
(-18 to -32) (-18 to -20)
ABS0811VHK (-12 to -16) HPL955 (-24 to -32) ABS0812VHK (-12 to -16) HPL956 (-24 to -32) ABS0876L (-10 to -14) HPL738 (-20 to -28) ASNA2026BV ASNA2026HK
(-3 to -10) HST755 VL755 AL755
(-6 to -20)
ASNA2026T (-3 to –6) HST755 VL755
(-6 to -12)
ASNA2027BV ASNA2027HK
(-3 to -10) HST756 VL756 AL12 AL756
(-6 to -20) (-6 to -20) (-6 to -12) (-14 to -20)
ASNA2027T (-3 to –6) HST756 VL756
(-6 to -12)
ABS0559VBV ABS0559VHK
(-12 to -16) HST956
(-24 to -32)
ABS0560VBV ABS0560VHK
(-12 to -16) HST955 (-24 to -32)
ASNA2026 (-3 to -16) HST803 (-6 to -32) ASNA2027 (-3 to -18) HST720
VL720 (-6 to -36)
Part ID Code (Proprietary or EN6114/EN6115 as appropriate)
Diameter code
Manufacturers identification (see below)
Grip length code is not marked and care should be taken to ensure that the correct grip length bolt is used.
Tightening speed limitations for A400M Overheating of fasteners/nuts shall be avoided. When using approved Electric Nut Runners for qualified fastener combinations stated in Appendix G, the torque tightening speeds shall be limited to the values as specified in the Rotational speed limitations table.
(115 – 125) 1) Note : Torque values 2.7 – 3.1 Nm (24 – 27 lbf.in) is applicable to EN6114T3 and EN6115T3 Bolts with ASNA2531-3 and ASNA2532-3 Nuts, assembled in combination with NAS1149C Steel Washers that have been wet installed and positioned under the nuts.
1 PROTRUSION For the bolt/nut combination to be adjudged to have set correctly, the protrusion of the bolt from the face of the joint shall be within the range tabulated below: -
Note: Not applicable for Oversize bolts
Table 3 - Bolt protrusion tolerances
Bolt Part Number
ASNA2026-, HK, BV, T ASNA2027-, HK, BV, T ABS0559VHK, VBV ABS0560VHK, VBV ABS0807K, ABS0907K ABS0809-, VHK ABS0810-, VHK ABS0811VHK ABS0812VHK EN6114-, K, V, L, T EN6115-, K, V, L, T
(1) Centre gauge over bolt at “Touch No-Go” end. (Fig. 2)
(2) If bolt touches top of “Touch No-Go” gauge - reject.
(3) If bolt does not touch, reverse gauge to “Touch-Go” end and check.
(4) If bolt touches top of “Touch-Go” gauge (Fig. 3) - accept
(5) If bolt does not touch top of “Touch-Go” gauge with legs on structures - reject.
Note 1: It could be possible on a specific joint thickness when a bolt is on maximum limits that the bolt will be rejectable to the requirements of Para 2 (2) and substituting with a bolt of the next shorter grip which is on minimum limits that it will be rejectable to the requirements of Para 2 (5).
In this situation the shorter bolt is acceptable provided the gap between the Touch-Go part of the gauge and the end of the bolt does not exceed 0.010 inch.
No similar relaxation i.e. the legs of the Touch-No Go gauge not contacting the structure, is allowable for bolts rejectable to Para 2 (2) because of the possibility of bolt thread bonding in the nut counterbore and consequent loss of clamping.
Note 2: If an installation is rejected based on the requirements of paragraph 2, sub-section (5). The nut shall be removed and the fastener shall be visually checked for full grip length. If the thread run-out/lead-in radius at the transition between the plain shank and thread is completely through the joint, the installation is acceptable providing it is compliant with the requirements of paragraph 2, sub-section (2).
2.1 These special installation instructions refer to the direct pull-in installation of break-stem (ABS0807K and ABS0907K) type fasteners as detailed in Figure 2 and the pull-in installation of point-drive (ABS0809, ABS0810, ABS0811VHK, ABS0812VHK and ABS0876L) fasteners using thread-in mandrel attachments as detailed in Figure 3.
2.2 It is the responsibility of the manufacturing or production engineering function to ensure that installation tools and pull-in loads appropriate to the fastener type and size are selected. Recommended tooling and maximum pull-in loads are defined in table 2. To prevent damage to the structure always select a pull-in gun that is set to the minimum calibration load.
2.3 The use of pull-in gun nose-cap extensions or collars to prevent damage or witness marking on the structure is acceptable providing the tooling does not foul or cause damage to the fastener during the installation process.
3. PULL-IN INSTALLATION
3.1 Installation methods shall be such as to avoid damage to the surrounding structure or assembly. Cases where protective treatments have been removed shall be re-treated in accordance with drawing specifications or the requirements of ABP 0-1013.
3.2 Where the fastener design calls for the use of a mandrel, it is at the discretion of the manufacturing or production engineering function whether the mandrel is installed prior to or after the fastener is offered and aligned with the hole. Care should be taken to ensure that the mandrel and fastener pull-in thread are clean and free from damage prior to installation (Note: mandrels can be re-used). The mandrel should be fully threaded (Left-Hand Thread) into the fastener ensuring that threads are fully engaged.
3.3 Where the drawing calls for high interference fit installations holes and hole entrance shall be lubricated with Boelube 70305 paste before fastener installation, taking care to ensure that the hole is clean and free from swarf and excess sealant before lubricant is applied. Prior to bolt installation all traces of Boelube 70305 shall be removed from the structure at the surface where the bolt head seats.
3.4 Once the fastener has been offered and aligned with the hole (and where appropriate the mandrel installed) the pull-gun grips should be engaged with the mandrel or pull stem (see Figure 2), ensuring that the fastener, tooling and hole remain axially aligned. The pull-gun unit should then be operated to pull the fastener into position.
3.5 If the fastener grip length exceeds the mandrel working length several pull-in operations may be required. A nose-cap extension or collar may be required to prevent fouling between the fastener and pull-in tooling. If the pull-in gun calibration load is insufficient to ensure full fastener installation the gun can be replaced with a gun having a higher calibration setting.
3.6 Pull-in fasteners shall not be used in carbon/CFRP interference holes.
4. MANDREL / STEM REMOVAL AND NUT INSTALLATION
4.1. Following bolt installation the pull-in gun shall be detached from the bolt stem or mandrel taking care to ensure that no damage occurs to the structure or bolt or to the associated pull-in tooling (gun, mandrel and nose piece extensions). Checks should then be made to ensure that the bolt head is properly seated in accordance with the requirements of ABP2-2336.
4.2. Once a satisfactory installation has been confirmed the mandrel should be removed ensuring that no damage occurs to the fastener or thread. For break-stem fasteners (ABS0807K and ABS0907K) the stem is removed from the main body of the fastener by a sharp bending or levering action designed to cause fracture in the necked region immediately below the thread, and applied using the gun / nose piece extension or other appropriate tooling (Figure 2). During this operation care should be taken to ensure that no damage occurs to the fastener, thread or surrounding structure.
4.3. Prior to nut installation remove excess sealant / lubricant from the threads with a clean cloth and check that the fastener protrusion meets the requirements defined in Appendix D table 3.
4.4. Install the nut using the procedures defined in this specification conforming to the torque tightening requirements detailed in Appendix C and ensuring that drawing invoked sealing instructions (e.g. ABP 4-5141 / ABP 4-5142) are observed.
5. DOCUMENTATION 5.1. The manufacturing or production engineering function shall generate supporting
manufacturing documentation to define:-
a. Detailed tooling set-up b. Part handling fixture requirements c. Detailed operator instructions with the correct installation and inspection sequences to
comply with the requirements of this specification.
Special Installation Requirements –Frangible Nuts/Collar 1. INSTALLATION PROCESS FOR DOUBLE HEXAGONAL NUTS
Step 1: Install nut with an approved socket by engaging the lower and upper hexagonal feature (double engagement) on the nut (figure 4) and applying relevant torque as indicated in appendix C. Step 2: If required, re-torque to the relevant torque value as indicated in appendix C due to
possible sealant relaxation. Step 3: Break off the upper hexagonal feature on the nut before the end of sealant assembly
time using suitable wrench. Torqued off area of the nut shall be protected in accordance with the requirement of the drawing.
APPENDIX G Qualified fastener combinations for Electric Nut Runners A400M Size -3 -4 -5 -6 -7 -8 -9 -10 -12 -14 -16 Bolt Nut EN6114T ASNA2531 X X X X X X ASNA2532 X X X X X X EN6115T ASNA2531 X X X X X X ASNA2532 X X X X X X
Special Installation Requirements - For L5755xxxx High Interference Fit Pull-In Studs
Note: L5755xxxx High Interference Fit Pull-In Studs shall be assembled with NAS5057 Nuts with the exception of –19, where NSA5373 Nuts shall be assembled.
1). Pre-installation hole geometry:
Unless otherwise specified the holes for L5755xxxx pull-in studs shall conform to the dimensions shown in figure 1 and tables 1 to 3. Additional hole details shall be in accordance with drawing requirements SL4477 and SL4478.
Note: If washers are used, then protrusion measurements shall be taken from washer-nut face (10B to 20B studs excluding 19B studs). For 19B diameter stud, use NSA5373 nut. Washers shall be used to ensure nut does not foul stud thread runout. Protrusion measurements shall be taken from surface of the component including washer(s) see figure 4.
3). L5755xxxx studs and NSA5057 nuts shall be torque tightened to the requirements shown in table 5, for 19B studs use NSA5373 nuts and assemble with Never-Seez (Nickel Special) grease compound see appendix 1 of ABP 2-2336. It is necessary to torque tighten both nuts per stud assembly.
Note: Both nuts on each stud assembly shall be torque tightened to the requirements shown above
(1). Nuts shall be assembled with Never-Seez (Nickel Special) Grease compound 4). The following process limitations shall be adopted:
- A maximum of 2 washers for each stud end is permissible as specified on drawing. - Unless otherwise specified on the drawing, the total thickness of washers for each stud end shall not exceed 1.6mm - Fastener assemblies shall be sealed as required by drawing. - The shrink fitting of fasteners contained within this specification are not permitted.
- Installation methods shall be such to avoid damage to the surrounding structure of the assembly. Cases where protective treatments have been removed shall be retreated in accordance with the requirements of ABP 0-1013.
- The use of pull-in gun nose-cap extensions or collars to prevent witness marking on the structure is acceptable providing the tooling does not foul or cause damage to the fastener
during the installation process. Collars shall not protrude within hole circumference as shown in figure 3.
- Oversize repairs shall be carried out under cover of non-conformance documentation as defined by the Airbus UK Limited Quality Authority.
- The removal of fastener threads to achieve protrusion tolerances is strictly prohibited.
- The pull-in gun load calibration setting shall not exceed the maximum allowable setting for each fastener type as defined in table 6.
- Following installation and nut torque tightening, the nut shall not foul the fastener shank, and there shall be at least 1 complete thread protruding beyond nut face.
- Studs shall not be re-installed once completely removed.
5). The following pull-in stud installation procedure shall be adopted by Manufacturing in addition to drawing requirements: Pre-Installation Checks
- The correct fastener grip length defined on drawing shall be checked and selected for a given stack thickness using a verification gauge approved by manufacturing.
- Washers shall be selected to maintain correct grip length as specified on drawing.
- Holes shall be checked to ensure that they meet the requirements specified on drawing and within this specification.
- Holes and hole entrance shall be completely lubricated with Boelube 70305 paste before fastener installation. Ensure that each hole is clean and free of swarf and excess sealant before lubricant is applied.
- Prior to bolt installation, all traces of Boelube 70305 paste shall be removed from structure at the surface where nut seats.
- A suitable tooling nut (non-crimped) shall be threaded onto plain stud end prior to stud installation. The nut shall be positioned to ensure that maximum protrusion (see table 4 and figure 4) is achieved at the plain stud end following stud pull-in.
- Ensure correct mandrel has been selected for fastener (table 6) and check fastener pull in thread and pull-in mandrel are clean and undamaged before use (mandrels may be re-used).
- Mandrels may be threaded into pull-in thread before or after the fastener has been offered and aligned with the hole.
- Thread mandrel (Left-Hand Thread) fully into fastener ensuring that threads are correctly engaged (see figure 4).
Stud Pull-In Installation - Select correct pull-in tooling for fastener (as shown in table 6).
- To prevent damage to the structure always select a pull-in gun that is set to the minimum calibration load. If the pull-in gun calibration load is insufficient to pull-in fastener, then a gun with a higher calibration load shall be selected.
- Ensure tooling is connected to approved power pack system.
- Locate puller-gun grips over mandrel grooved and ensure fastener and tooling is axially aligned with the hole.
- Puller gun units shall be operated to pull the fastener into the hole (figure 5); several pull-in operations my be required if the fastener grip length exceeds the mandrel working length. A nose-ca extension or collar may be required to fervent fouling between fastener and pull-in tooling. - If puller gun calibration load is insufficient to pull-in fastener, then gun can be replaced with a gun set to a higher calibration load. - Following installation, ensure that stud nut is fully seated and conforms to the requirements shown in figure 2 and table 4.
Tooling and Mandrel Removal - Remove pull-in gun from mandrel ensuring that damage to mandrel or gun does not occur
(figure 6).
- Remove mandrel from fastener without causing damage to the fastener (figure 6).
- Inspect structure for visible signs of damage or witness marks caused by pull-in tooling.
Nut Installation - Remove excess sealant/lubricant from threads with a clean cloth.
- Check fastener protrusion using verification gauges/visual checks and install washers to drawing requirements.
- Thread nut onto stud and torque tighten to the requirements specified in table 5.
- To control the protrusion of studs, it is permissible to adjust the position of the fastener within the hole by loosening one nut end and torque tightening the opposing nut (providing applied torque does not exceed limits of table 5).
- Check installation of fastener and nut meet the seating and protrusion requirements defined within this specification.
6). Nuts shall be over-sealed to the requirements specified on drawing.
- For the over-sealing of nuts on the pull-in end of studs only; over-sealing shall be undertaken in accordance with ABP 4-5141 with the exception that sealant dimensions are allowed to