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USAF Aircraft Structural Integrity Program (ASIP)USAF Aircraft Structural Integrity Program (ASIP)
San Antonio, TexasSan Antonio, Texas
28 28 –– 30 November 200630 November 2006
Damage ToleranceDamage ToleranceFacts and FictionFacts and Fiction
Dr. Ulf G. Dr. Ulf G. Goranson Goranson (Retired)(Retired)
Boeing Commercial Airplane CompanyBoeing Commercial Airplane Company
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Damage Tolerance – Facts and Fiction
Overview
Elements of Damage Tolerance
Structural Maintenance Considerations
Continuing Airworthiness Challenges
Summary
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Royal Institute of Technology - StockholmDepartment of Aeronautics 1958 - 1965
Aeronautical Research Laboratory 1962 -1967
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SAAB 37-Viggen - First Flight 1965
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Boeing Commercial Airplane Company1967 - 2001
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Boeing B-2707 Supersonic Transport
Page 7
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Boeing Family of Commercial Aircraft
Page 8
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Inger and Ulf 50 year Celebration Cruise
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Damage Tolerance – Facts and Fiction
OverviewElements of Damage Tolerance
Structural Maintenance Considerations
Continuing Airworthiness Challenges
Summary
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Design Principles
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Boeing BW-12
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Boeing BW-12 ReplicaBoeing 50th Anniversary 1966
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Boeing Model 40
“…let no new improvement in flying andflying equipment pass us by”
W.E. Boeing - 1929
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777 Static Test
Wing Tip Deflection:
- 18 feet & 2.50g
- 24 feet & 3.75g
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Design Principles
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Boeing Clipper 314
Page 18
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Boeing 377 - Stratocruiser
Page 19
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De Havilland Comet
Page 20
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Design Principles
Page 21
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Fail-Safe Jet Transports
Page 22
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Boeing 707
Page 23
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Wing Fail Safety
Page 24
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Fail-Safe Test Verification
Pressurized test section• Example of blade skin cuts made at
critical locations
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Fuselage Crack Arrest Test
Page 26
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Hull Losses and/or Fatal AccidentsPer Million Departures
Worldwide commercial jet fleet — 1959 through 2005
Structures = 4%
All othercauses
Maintenance = 14%• Structures• Systems• Propulsion
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Structural Safety System
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Design Principles
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FAA Regulation Comparisons
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Boeing 757 and 767
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Basic Concepts
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Damage Tolerance Constituents
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Damage Tolerance – Facts and Fiction
Overview
Elements of Damage ToleranceStructural Maintenance Considerations
Continuing Airworthiness Challenges
Summary
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Vision
Elements of Damage Tolerance
Allowabledamage
Damagegrowth
Damagedetection
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Research Community Focus
Elements of Damage Tolerance
Allowabledamage
Damagegrowth
Damagedetection
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Lecture Focus
Elements of Damage Tolerance
Allowabledamage
Damagegrowth
Damagedetection
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Interaction of Damage Tolerance Elements
Requiressafe-lifedesign
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Damage Tolerant Structure
Ultimate loadcapability requiredafter damagedetection
Regulatory fail-safe requirement
Damage detectionand restorationUltimate
Structuralstrength
NDIdetectionperiod
Visualdetectionperiod Damage
size
Max. Allowable damage
Visual
NDI
Damagedetectionthresholds
Service time
Operating loads
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Adequate residualstrength with extensivedamage obvious duringwalkaround or indicatedby malfunction
Wing spoiler segment(safe separation orsafe loss of function)
Safetyanalysisrequirements
Damagedetection byplannedinspection
Damagetolerantdesign
Structurallysignificantitems orprincipalstructuralelements(primarystructure)
Damageobvious ormalfunctionevident
Secondarystructure
1
2
3
4
• Residualstrength
• Crackgrowth
• Inspectionprogram
Safe lifeSafe-lifedesign
Otherstructure
Structural category Technique ofensuring safety
Structuralclassificationexamples
Design for loss ofcomponent or safeseparation
Inspection programmatched to structuralcharacteristics
Conservative fatiguelife
• Continuedsafe flight
• Residualstrength
• Fatigue
Wing fuel leaks
Landing gear structure(conservative fatiguelife)
All primary structurenot included incategories
2 4or
Classification of StructuresCategory 3 : Inspections match Structural Characteristics
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Structural Technology StandardsDurability Methods and Allowables
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Technology Standards Development
Page 42
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Fatigue Check ProcedureStructural Capability Analysis
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Fatigue Damage Model
1P
105
Cyclic life
Alternatingstress
log n Mean stress fm
Alternatingstress
105
DFR
DFR= fatigue rating (fmax at N=105 and R = 0 with 95% reliability and 95% confidence)fmo = focal mean stressP = slopeφ = load sequence factor
P1
N10
1DFRf2
fff
5
mo
mmoa ⎟
⎟⎠
⎞⎜⎜⎝
⎛
φ⋅⎟⎟⎟⎟
⎠
⎞
⎜⎜⎜⎜
⎝
⎛
−⎟⎠⎞⎜
⎝⎛
−=
fmo
fmax
fa
fm = constant
log fa
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Required Fatigue Rating Solution
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Relative Operating Stress LevelsWing & Fuselage Capability Examples
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Durability Design Guide ExampleSpar Chord Discontinuity
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Relativestress
Alloy factor (B)
2024 1.07075 10.8
Hole-filling factor (A)
Standard rivet 1.10Fluid-tight rivet 1.14
Cycles (N)
DFR = DFR BASE x ABCDEU
Reference
Analytical Detail Fatigue Ratings
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Fatigue Check ProcedureRequirement Analysis
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Design Service Objectives
Relativenumber of
flights
Fleet use
Design service goals
Short G Medium G Long Crack free(< 1% cracking)
Economic repair(< 5% cracking)
Fatigue-check missions
Range
1.5
1.0
G
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Fatigue Check Examples
Fatigue check summary
Flight profile damage data
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Fatigue Design Requirement Contours
• Required fatigue rating tomeet short, medium, and longflight design service goals
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Copyright © 2006 Boeing. All rights reserved. DM2220.462 h
MostPreferred • Fleet Experience
• Full-Scale Airplane Test
• Part Airplane Test
• Component Test
• Fleet Full-Scale Part Airplane Or Component Test
• Small-Scale Laboratory Specimen
+
Modified UsingSmall-ScaleLaboratory Specimen
}
Structural Durability ValidationSources for Detail Fatigue Ratings
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Test Versus Service
Pros and Cons
Page 54
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Service Bulletin Modifications - Labor-HoursCorrosion and Fatigue
Page 55
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Design Service Objectives 767 Jet Transports
Database from 586 active 767s
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Service-Demonstrated Fatigue Lives
Number ofairplanesdelivered
1
ModelDemonstrated
life103 flights
3
Highestflights
103 flights2
1999 commercial fleet dataService - demonstrated
characteristic lifeService -demonstrated reliable life
Number of airplanes
NA/P
β
Fleet utilization curve
Number of flights
Assumed life to first crack N airplanes
0.95
1
2
3
707
720
727
737
747
757
767
777
737NG
735
153
1,822
3,440
1,214
880
753
239
351
36
45
77
92
33
27
33
4
TBD
39
35
103
109
33
25
28
2
TBD
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Boeing Fleet Support ActionsWing/Fuselage Teardowns
Durability standards
Wing/fuselage teardowns
Damage tolerance methods
Supplemental inspection programs
Fatigue tests
Fleet survey program
Worldwide conferences
Aging fleet initiatives
707 727 737 747 7277 777 7 7
707 727/737/747 757/767
747/737/727707 727 747 757 767 777 737NG
Regionalbriefings
Service entry dates707 727 747737 757767
777737NG
757-300767-400
1955 60 65 70 75 80 85 90 95 2000
Year
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737 Teardown Site
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Boeing Fleet Support ActionsFull Scale Fatigue Tests
Durability standards
Wing/fuselage teardowns
Damage tolerance methods
Supplemental inspection programs
Fatigue tests
Fleet survey program
Worldwide conferences
Aging fleet initiatives
707 727 737 747 727 777
707 727/737/747 757/767
747/737/727707 727 747 757 767 777 737NG
Regionalbriefings
Service entry dates707 727 747737 757767
777737NG
757-300767-400
1955 60 65 70 75 80 85 90 95 2000
Year
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Boeing Full-Scale Fatigue TestsFleet Leader Test Margins
Pressure cycles, in thousands
Boeing fatigue testing
Fleet leader—high-timeairplane (flights)
Design service objective
707
727
737
747
757
767
777
737NG
0 20 40 60 80 100 120 140 160 180 200 220 240
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747 FATIGUE TESTSService Airplane and Redesigned Section 41
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Major Airframe Fatigue Tests
• 757 and 767 minimum design service objective = 50K flight cycles
• 747 minimum design service objective = 20K flight cycles
• 777 minimum design service objective = 40K flight cycles
Extended 777 fuselage test
757
767
747
Percentage of design service objective, 20 years
350
300
250
200
150
100
50
00 2 4 6 8 10 12 14 16 18 20 22 24 26 28 29
Testing, months
777
• 28 design changes
• 30 design changes
• 23 design changes
• 121 design changes
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Boeing Fleet Support ActionDamage Tolerance Methods
Durability standards
Wing/fuselage teardowns
Damage tolerance methods
Supplemental inspection programs
Fatigue tests
Fleet survey program
Worldwide conferences
Aging fleet initiatives
707 727 737 747 727 777
707 727/737/747 757/767
747/737/727707 727 747 757 767 777 737NG
Regionalbriefings
Service entry dates707 727 747737 757767
777737NG
757-300767-400
1955 60 65 70 75 80 85 90 95 2000
Year
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Elements of Damage Tolerance
Residual StrengthTechnology StandardsTest VerificationLessons Learned
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Static behavior
Transition behavior
Regulatory Requirement
LEFM behavior
Maximum allowable damage
Residual Strength Residual Strength Parameters
L
GeometryGeometry Correction
Factor
Y B
Thickness
MaterialFracture Toughness
Kapp
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Residual Strength Verification DataPanel widths: 8”- 90” Crack Lengths: .02” - 24”
Normalized crack length, L/LY
1.0
0.5
00.01 0.1 1 100.001 100
LEFM analysis LLY = boundarybetween LEFM andtransition behavior
Transitionanalysis
Panel widths:200 to 2,300 mm
Crack lengths:0.5 to 600 mm
Transition tonet sectionyielding
LEFMregion
Normalizedstrength
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Cracking PatternsStress Intensity Factors - Y Redistribution Factors - C
Recommended crack configurationsBased on experience and engineering judgement
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Load Redistribution Factors - C
C factors account for change in reference stress due to cracks in adjacent parts
Page 69
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Fuselage Pressure Test Fixture
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Page 71
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Typical Pressure Test Panel
Page 72
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Verification Test - Safe Decompression
Page 73
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Fuselage Test Panel - Riveted Tear StrapsDynamic Crack Extension (20 in. to 100 in.)
Page 74
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Local Damage Versus MSD or MED
Page 75
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Lap Joint Residual Strength Comparison
Page 76
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Elements of Damage Tolerance
Residual Strength
Crack GrowthTechnology StandardsTest VerificationLessons Learned
Page 77
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Crack Growth Technology Standards
Page 78
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Total length of lead crack when detectable, L0.1 1
Length ofsecondarycracks
0.01
0.1
Type ISame hole,same piece(becomes partof lead crackafter growingthroughthickness)
Type IISame hole,differentpiece
Type IIIIndependent
Type III crack(4 places)
Type I crack
Type II crack(2 places)
Lead crack
L
Local Multiple-Site CriteriaI: Same Hole & Piece II: Same Hole / Different Piece
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Damage Detection PeriodFlights to Critical Crack Size
Cracklength
Cracklength
Critical Critical
Surveillance
Detailed
NDI
Surveillance
Detailed
NDI
Crack growth interval,flight cycles
Damage detection periodflights to critical
Page 80
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Material AMaterial B
p
1
MA MB
Growthrate
Stress intensity, K
M—Measures relative material resistance to crack growth
Material Crack Growth Rating Concept
StandardStandard⎟⎟⎠
⎞⎜⎜⎝
⎛⋅= −
MZK10n
dNdL p
max4
dNdL
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Geometry Factor ConceptStress Intensity Factor for Unit Stress - (L1 to L2)
Page 82
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Simple Chart for Geometry Integral G
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TEST
COUPON
p
M
Cra
ck g
row
th ra
te (i
n/cy
cle)
Stress intensity
Crack Growth ConceptsCrack Growth Rate Equation
M & p = Material crack growth rate parameters• Measures relative material resistance to crack
growth• Reflects effect of environment
dndL
n1log
log Z Kmax
10-4
pmax4
MKZ10n
dNdL
⎟⎠⎞
⎜⎝⎛ ⋅
⋅= −
where
( )
⎪⎪⎩
⎪⎪⎨
⎧
≥−≤≤<−⋅−<<−
=
0.1R00.1R1.1
0.0R0.1R1.010.1R0.0R1
Z
q
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Stress Rating – Equivalent Stress ConceptCrack Growth Spectrum Effects Measure
Page 85
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Test Spectra Characteristics5x5 Spectra: 5 Flight Types & 5 Levels per segment
Page 86
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Wing Lower Surface Spectrum(5x5 Spectra - Flight Mix)
Flight E (Applied 3,704 Times per 5,000 Flights)
Relativestress
Control point number
0
1
Flight E (Applied 1,067 Times per 5,000 Flights)
Relativestress
Control point number
0
1
Flight C (Applied 215 Times per 5,000 Flights)
Relativestress
Control point number
0
1
Flight B (Applied 13 Times per 5,000 Flights)
Relativestress
Control point number
0
1
Flight A (Applied One Times per 5,000 Flights)
Relativestress
Control point number
0
1
0 200 400 600 800 1,000 1,200 1,400
0 40 80 120 160 200 240 280
0 100 200 300 400 500 600 700
0 20 40 60 80 100 120
0 25 50 75
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Page 88
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Multiple-site Damage - Link-up Criteria Effects on Detection Period
Page 89
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MSD Link- up Comparison747-400 Fuselage Lap Splice Test – Stringer 44Left
Page 90
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Elements of Damage Tolerance
Residual Strength
Crack Growth
Damage DetectionTechnology StandardsTest VerificationLessons Learned
Page 91
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Damage Detection Parameters
Page 92
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Opportunities for Damage Detection
Page 93
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Probability of detecting damage
Probability of inspecting an aircraft with
damage
Probability of inspecting detail
considered
Probability of crack detection
Damage Detection Considerations
Page 94
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Distributions of Cracks Found in Service
Page 95
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Relative Probability of Detection Visual Inspection Methods
General visual
Surveillance
Detailed
0.990.90
0.50
0.100.05
0.0100.005
0.001
0.0005
0.100.05 0.1 0.2 0. 5 1 2 5 10 20 50
Relative inspectable crack length
Probabilityof
detection
(P3)∧
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Detection and Non-detection Events
Successful detectionsUnsuccessful inspectionsaccounted for in analysisUnsuccessful inspectionsnot accounted for inanalysis
Detectionat futuredate
Airplaneretiredprior to crackdetection
Flights
Cracklength (L)
LD
Li
N
Flights to crack detection
1
Page 97
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Visual and NDI Damage Detection Periods
Relativedamage size
4
3
2
1
00 1 2 3 4
Visualinspection
NDI inspectionRelativedetection period
Broken
Critical
Stringer
Skin Inspectiondirection
Wing Lower Surface Splice Stringer
Page 98
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0.0001
0.001
0.01
0.1
1
0.1 1 10 100
Inspectable Crack Length (in)
Pro
babi
lity
of D
etec
tion
Probability of Detection Parameters Visual Inspections
Flights
N N N N N
Cra
ck L
engt
h
Need to relate:
Inspection method
Probability of detection
Crack length
Safe damage detection period
Audited by the FAA in 1980
Detailed
Surveillance
General Visual
Page 99
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Probability of Crack Detection, PD
Cumulative probability of damage detection during the safe damage detection period N is given by
Where 1 = applicable inspection levels (A, B, C, D, or S)A-check: Visual inspection conducted from ground level
B-check: Close visual inspection of aircraft exterior
C-check: Close visual inspection of aircraft exterior and easily accessible interior areas
D-check: Detailed inspection of entire aircraft
S (special): Directed visual or NDI inspection of specific components
Page 100
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Measurement of Detection Probability, DTR
Probability of detection (PD)
Damagetolerancerating (DTR)
0.5 0.96875 0.999 0.99996951
5
10
15
Nondetections
Nondetections
Detection
DTRD 211P −=
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The total DTR resulting from a surveillance inspection at 3000 flights is more than the required
DTR for this structure.
Damage Tolerance Rating (DTR) FormDetection Probability versus Inspection Intervals & Methods
Page 102
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Damage Tolerance – Facts and Fiction
Overview
Elements of Damage Tolerance
Structural Maintenance ConsiderationsContinuing Airworthiness Challenges
Summary
Page 103
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Structural Maintenance Considerations
Inspection thresholds
Page 104
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Fleet Damage SourcesInspection Program Phases
Page 105
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Fleet Cracking Order
Page 106
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Variation of Minimum Life With Fleet Size
Page 107
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Structural Maintenance Considerations
Inspection Options
Fleet Sampling Options
Page 108
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Probability of detecting damage
Probability of inspecting an aircraft with
damage
Probability of inspecting detail
considered
Probability of crack detection
Probability of Damage DetectionP1 – Probability of Inspecting Airplane with Damage
Page 109
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Probability of Inspecting Damaged Aircraft - P1Rotational Sampling : Sequential Inspections of all Airplanes
Page 110
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Structural Maintenance Considerations
Inspection thresholds
Fleet Sampling Options
Inspection Intervals
Page 111
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Structurally Significant Items767 Outer Wing Box
Page 112
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Crack Growth Analysis Example Spar Chord Details
Page 113
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Structural Maintenance Considerations
Inspection thresholds
Fleet Sampling Options
Inspection Intervals
Damage Detection Considerations
Page 114
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Actual Crack Growth Curve
Inspection access: top
Inspection access: bottom
Inspectable Crack Growth Curves
Inspection access:Top
Bottom
FlightsNC NA NB
Totalcracklength
Inspectablecracklength
FlightsNC NA NB
B C
A
Lcritical
CBA
Inspectable Crack Length
Page 115
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Cumulative Detection ProbabilityInspection Interval Selection
Cracking pattern/inspection direction combinations
Page 116
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Cumulative Detection Probability
Page 117
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Structural Maintenance Considerations
Inspection thresholds
Fleet Sampling Options
Inspection Intervals
Damage Detection Considerations
Multiple Inspections
Page 118
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12/13/2006Filename.ppt | 118
Multiple Aircraft Cracking in the Fleet
Page 119
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12/13/2006Filename.ppt | 119
Cumulative detection probability
Multiple fleet cracking contributions to damage protection
Page 120
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Cumulative Detection Probability
Fleet inspection detection contributions limited to 50% of total
Page 121
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Damage Tolerance – Facts and Fiction
Overview
Elements of Damage Tolerance
Structural Maintenance Considerations
Continuing Airworthiness ChallengesSummary
Page 122
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12/13/2006Filename.ppt | 122
Boeing Fleet Support ActionsFleet Survey Program
Durability standards
Wing/fuselage teardowns
Damage tolerance methods
Supplemental inspection programs
Fatigue tests
Fleet survey program
Worldwide conferences
Aging fleet initiatives
707 727 737 747 727 777
707 727/737/747 757/767
747/737/727707 727 747 757 767 777 737NG
Regionalbriefings
Service entry dates707 727 747737 757767
777737NG
757-300767-400
1955 60 65 70 75 80 85 90 95 2000
Year
Page 123
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12/13/2006Filename.ppt | 123
Boeing Fleet Survey ProgramInitiated 1987
22
8
15
1
4420
20 Number of operators by regionNumber of operators by region
Page 124
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Boeing Fleet Surveys200 Airplanes; 103 Operators; 49 Countries
1989–1998
1987–1988
Number of planesfor 1999
( )
707/720 727 737/200 747 737/300 757 767
60
50
40
30
20
10
0
Number of airplanes
• September 1999• 200 airplanes surveyed• 103 operators visited in 49 countries
12 (0)
50 (0)
46 (0)42 (0)
23 (0)
15 (0)12 (1)
Page 125
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Fleet Survey Findings
Page 126
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12/13/2006Filename.ppt | 126
Fleet Survey Findings
Page 127
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Boeing Fleet Support ActionsAging Fleet Initiatives
Durability standards
Wing/fuselage teardowns
Damage tolerance methods
Supplemental inspection programs
Fatigue tests
Fleet survey program
Worldwide conferences
Aging fleet initiatives
707 727 737 747 727 777
707 727/737/747 757/767
747/737/727707 727 747 757 767 777 737NG
Regionalbriefings
Service entry dates707 727 747737 757767
777737NG
757-300767-400
1955 60 65 70 75 80 85 90 95 2000
Year
Page 128
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12/13/2006Filename.ppt | 128
Aloha Airlines 7371988 Explosive Decompression
1988
Page 129
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12/13/2006Filename.ppt | 129
Government and Industry Task Groups
Page 130
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12/13/2006Filename.ppt | 130
Continued Airworthiness –Industry Initiatives
Structures Task Groups
Reviewservicebulletin
Developcorrosion
controlprogram
Reviewbasic
maintenanceprogram
Reviewsupplemental
structuralinspectionprogram
Assesswidespread
fatigueAssessrepairs
Publishmodel-specific
documents
Recommendservice bulletinfor compliance
Recommendimplementation
Recommendrevisions to
supplementalstructural inspection
program
Recommendsupplementalinspections
Airworthinessdirectives
Federal aviationregulation
1990 1993 1994 OEM Audit 2001 1999
Page 131
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12/13/2006Filename.ppt | 131
Continued Airworthiness-Industry Initiatives
Structures Task Groups
Reviewservicebulletin
Developcorrosion
controlprogram
Reviewbasic
maintenanceprogram
Reviewsupplemental
structuralinspectionprogram
Assesswidespread
fatigueAssessrepairs
Publishmodel-specific
documents
Recommendservice bulletinfor compliance
Recommendimplementation
Recommendrevisions to
supplementalstructural inspection
program
Recommendsupplementalinspections
Airworthinessdirectives
Federal aviationregulation
1990 1993 1994 OEM Audit 2001 1999Implementation:
Page 132
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Continuing Airworthiness Challenges
Mandatory Service Bulletin Modifications
Page 133
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12/13/2006Filename.ppt | 133
Typical 727 High-Time Modifications
Reinforce Wing Rib ReplaceSkin Rivets
Reinforce Fin Reinforce Horizontal Stabilizer
StrengthenWindow Frame
Replace Doorstop Replace FlapTrack Bolts
Page 134
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12/13/2006Filename.ppt | 134
Mandatory Service Bulletin Modifications727 Horizontal Stabilizer Front Spar - Stress Corrosion Problems
Center sectionfront spar
Action: Replace the existing 7079 fittingwith 7075-173 fitting at 60,000 flight cycles or 20 years, whicheveroccurs first.
Up
Forward
Page 135
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Typical 737 High-Time Modifications
Page 136
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Typical 747 High-Time Modifications
ReplaceBody Frames
ReinforceWing Rib
Install Rivets Through Tearstraps
ReplaceSkin Rivets
Reinforce Wing Lower Splice
ReplaceFlap Track
Page 137
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12/13/2006Filename.ppt | 137
Continued AirworthinessIndustry Initiatives
Structures Task Groups
Reviewservicebulletin
Developcorrosion
controlprogram
Reviewbasic
maintenanceprogram
Reviewsupplemental
structuralinspectionprogram
Assesswidespread
fatigueAssessrepairs
Publishmodel-specific
documents
Recommendservice bulletinfor compliance
Recommendimplementation
Recommendrevisions to
supplementalstructural inspection
program
Recommendsupplementalinspections
Airworthinessdirectives
Federal aviationregulation
1990 1993 1994 OEM Audit 2001 1999Implementation:
Page 138
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Contributing Causes of Corrosion
Page 139
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12/13/2006Filename.ppt | 139
Corrosion Program Areas
Page 140
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AAWG Status
On June 29, 2001, the AAWG submitted a Proposed Operational Ruleto ARAC on the Control and Prevention of Widespread Fatigue Damage (WFD) in the Commercial Transport Fleet.
Once finalized the rule will require the use of maintenance programs that address the potential occurrence of WFD as the airplanes age. Operation of the airplane will be prohibited beyond the stated Limits of Validity (LOV) of the Maintenance Program unless an approved amendment is incorporated to address any WFD concerns.
The issuance of the rule will represents closure of all issues resulting from the April 1988 Aloha Accident.The AAWG is now focusing on supplemental type certificates (STC)
Page 141
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The 727 Corrosion Prevention Program
External Doors and Landing Gear Bay 6yr/1.5yr*
Outboard Main Wingbox Interior 10yr/10yr*
Bilge 6yr/3yr*
Fuselage Upper Lobe Interior 10yr/8yr*
Fin and Horizontal Stabilizer Interiors 10yr/8yr*
* Initial Implementation/Repeat Interval in Years.
Page 142
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12/13/2006Filename.ppt | 142
727 Corrosion Control ProgramFuselage Structure Example
(Including landing gear bays)All external surfaces 6/1.5*
Under fairings andair-conditioning doors 6/6*
Upper lobeabove bilge 6/6*
*Threshold interval (years)
Bilge 6/3*Bilge 6/3* Upper lobeabove bilge 6/6*
Upper lobe and floors 10/8* Section 48 10/5*
Page 143
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12/13/2006Filename.ppt | 143
Corrosion Control Improvements
727 Airplane
Page 144
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12/13/2006Filename.ppt | 144
Stringer Drainage and Sealing- Lower Lobe
Page 145
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12/13/2006Filename.ppt | 145
Service Bulletin Modifications - Labor-HoursCorrosion and Fatigue
Page 146
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12/13/2006Filename.ppt | 146
Effects of Corrosion Control Improvements on the 747
Reported corrosion events
0
100
200
300
400
500
600
700
747 wing skins * Finish improvements
747 wing spar chords *Material change *Finish improvements *Fay surface sealant
Line numbers 1 to 200
Line numbers 400 to 540
10-year service comparison
Page 147
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12/13/2006Filename.ppt | 147
Test Versus Service
-100/-200/-300/-400/SP/SR
Page 148
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12/13/2006Filename.ppt | 148
Continuing Airworthiness Challenges
Mandatory Service Bulletin Modifications
Corrosion Prevention and Control Programs
Maintenance Programs
Page 149
Copyright © 2006 Boeing. All rights reserved.
12/13/2006Filename.ppt | 149
Continued Airworthiness Industry Initiatives
Structures Task Groups
Reviewservicebulletin
Developcorrosion
controlprogram
Reviewbasic
maintenanceprogram
Reviewsupplemental
structuralinspectionprogram
Assesswidespread
fatigueAssessrepairs
Publishmodel-specific
documents
Recommendservice bulletinfor compliance
Recommendimplementation
Recommendrevisions to
supplementalstructural inspection
program
Recommendsupplementalinspections
Airworthinessdirectives
Federal aviationregulation
1990 1993 1994 OEM Audit 2001 1999
Page 150
Copyright © 2006 Boeing. All rights reserved.
12/13/2006Filename.ppt | 150
Continued Airworthiness Industry Initiatives
Structures Task Groups
Reviewservicebulletin
Developcorrosion
controlprogram
Reviewbasic
maintenanceprogram
Reviewsupplemental
structuralinspectionprogram
Assesswidespread
fatigueAssessrepairs
Publishmodel-specific
documents
Recommendservice bulletinfor compliance
Recommendimplementation
Recommendrevisions to
supplementalstructural inspection
program
Recommendsupplementalinspections
Airworthinessdirectives
Federal aviationregulation
1990 1993 1994 OEM Audit 2001 1999
Page 151
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12/13/2006Filename.ppt | 151
Maintenance Planning Process
Page 152
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12/13/2006Filename.ppt | 152
Continuing Airworthiness Challenges
Mandatory Service Bulletin Modifications
Corrosion Prevention and Control Programs
Maintenance Programs
Supplemental Inspection Programs
Page 153
Copyright © 2006 Boeing. All rights reserved.
12/13/2006Filename.ppt | 153
Continued Airworthiness Industry Initiatives
Structures Task Groups
Reviewservicebulletin
Developcorrosion
controlprogram
Reviewbasic
maintenanceprogram
Reviewsupplemental
structuralinspectionprogram
Assesswidespread
fatigueAssessrepairs
Publishmodel-specific
documents
Recommendservice bulletinfor compliance
Recommendimplementation
Recommendrevisions to
supplementalstructural inspection
program
Recommendsupplementalinspections
Airworthinessdirectives
Federal aviationregulation
1990 1993 1994 OEM Audit 2001 1999Implementation:
Page 154
Copyright © 2006 Boeing. All rights reserved.
12/13/2006Filename.ppt | 154
Boeing Fleet Support Actions
Durability standards
Wing/fuselage teardowns
Damage tolerance methods
Supplemental inspection programs
Fatigue tests
Fleet survey program
Worldwide conferences
Aging fleet initiatives
707 727 737 747 727 777
707 727/737/747 757/767
747/737/727707 727 747 757 767 777 737NG
Regionalbriefings
Service entry dates707 727 747737 757767
777737NG
757-300767-400
1955 60 65 70 75 80 85 90 95 2000
Year
Page 155
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12/13/2006Filename.ppt | 155
Continuing Airworthiness Challenges
Mandatory Service Bulletin Modifications
Corrosion Prevention and Control Programs
Supplemental Inspection Program Reviews
Page 156
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12/13/2006Filename.ppt | 156
Supplemental Inspections - Airplane SelectionCandidate Fleet v.s Inspection Threshold
1999 Status
Page 157
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12/13/2006Filename.ppt | 157
Supplemental Inspection Threshold
Fleet Utilization Distribution
Page 158
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12/13/2006Filename.ppt | 158
Continuing Airworthiness Challenges
Mandatory Service Bulletin Modifications
Corrosion Prevention and Control Programs
Maintenance Programs
Supplemental Inspection Programs
Widespread Fatigue Damage
Page 159
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12/13/2006Filename.ppt | 159
Continued Airworthiness –Industry Initiatives
Structures Task Groups
Reviewservicebulletin
Developcorrosion
controlprogram
Reviewbasic
maintenanceprogram
Reviewsupplemental
structuralinspectionprogram
Assesswidespread
fatigueAssessrepairs
Publishmodel-specific
documents
Recommendservice bulletinfor compliance
Recommendimplementation
Recommendrevisions to
supplementalstructural inspection
program
Recommendsupplementalinspections
Airworthinessdirectives
Federal aviationregulation
1990 1993 1994 OEM Audit 2001 1999Implementation:
Page 160
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12/13/2006Filename.ppt | 160
Widespread Damage
Page 161
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12/13/2006Filename.ppt | 161
Structure Susceptible to WFTypical Examples
Page 162
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12/13/2006Filename.ppt | 162
Structure Susceptible to WFD Cont’d
Page 163
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12/13/2006Filename.ppt | 163
WFD Graphical Representation
Page 164
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12/13/2006Filename.ppt | 164
Limit of Validity
Page 165
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12/13/2006Filename.ppt | 165
ISP and SMP Graphic Representation
Page 166
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12/13/2006Filename.ppt | 166
Preliminary LOVs
Page 167
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12/13/2006Filename.ppt | 167
Continuing Airworthiness Challenges
Mandatory Service Bulletin ModificationsCorrosion Prevention and Control ProgramsSupplemental Inspection Program ReviewsWidespread Fatigue DamageStructural Repair Assessments
Page 168
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12/13/2006Filename.ppt | 168
Continued Airworthiness –Industry Initiatives
Structures Task Groups
Reviewservicebulletin
Developcorrosion
controlprogram
Reviewbasic
maintenanceprogram
Reviewsupplemental
structuralinspectionprogram
Assesswidespread
fatigueAssessrepairs
Publishmodel-specific
documents
Recommendservice bulletinfor compliance
Recommendimplementation
Recommendrevisions to
supplementalstructural inspection
program
Recommendsupplementalinspections
Airworthinessdirectives
Federal aviationregulation
1990 1993 1994 OEM Audit 2001 1999Implementation:
Page 169
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12/13/2006Filename.ppt | 169
Typical Fuselage External Skin Repair
Page 170
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12/13/2006Filename.ppt | 170
Repair Assessment Task Group
Charter
RepairAssessmentTask Group
Page 171
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12/13/2006Filename.ppt | 171
Fuselage Repair Size Distributions
Page 172
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12/13/2006Filename.ppt | 172
Repair Assessment Stages
Page 173
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12/13/2006Filename.ppt | 173
Stage 1 - Assessment Area
Page 174
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12/13/2006Filename.ppt | 174
Stage 2 - Repair Categorization
Page 175
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12/13/2006Filename.ppt | 175
Category C Repair Examples
Page 176
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12/13/2006Filename.ppt | 176
Structurally Not Satisfactory Repair Examples
Page 177
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12/13/2006Filename.ppt | 177
Stage 3 - Supplemental Inspections
Page 178
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12/13/2006Filename.ppt | 178
Repair Assessment Thresholds Manufacturer Recommendations
Page 179
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12/13/2006Filename.ppt | 179
Inspection Threshold Requirements
Page 180
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12/13/2006Filename.ppt | 180
Assumed Baseline Inspection Intervals727 Repair Assessments
Horizontal stabilizer
Vertical stabilizer
Center section
Outboard
15,000Strut
20,000
20,000Internal
3,000External
Empennage
6,000Section 48 internal
15,000/9,000Lower lobe internal/bilge
20,000Upper lobe internal
3,000Lower lobe external
6,000Upper lobe external
Fuselage
20,000
15,000Wing box (internal)
3,000Trailing-edge cavity
3,000Leading-edge cavity
3,000External
Wing
Baselineinspection intervals
(flight cycles)
Structure (surveillance inspection)
Page 181
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12/13/2006Filename.ppt | 181
Repair Inspection Options –Inspection Intervals/Methods
Page 182
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12/13/2006Filename.ppt | 182
Repair Inspection Options –Inspection Intervals/Methods
Fatigue Skin Repairs
Option 1: Internal HFEC per curve 1 of skin at all fastener locations on critical row of repair.
Option 2: For lap splice repairs, external LFEC per cur 2 (if within NDT procedure limits) at all fastener locations on thecritical row of repair.
Option 3: Internal visual surveillance per curve 3 of skin at all fastener locations on the critical row of repair
Option 4: Internal detailed visual per curve 4 of skin at all fastener locations on critical row of repair.
1 Adjust intervals as required for other zones by appropriate zone factor.
Page 183
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12/13/2006Filename.ppt | 183
Damage Tolerance – Facts and Fiction
Overview
Elements of Damage Tolerance
Structural Maintenance Considerations
Continuing Airworthiness Challenges
Summary
Page 184
Copyright © 2006 Boeing. All rights reserved.
12/13/2006Filename.ppt | 184
Boeing Fleet Support Actions
Durability standards
Wing/fuselage teardowns
Damage tolerance methods
Supplemental inspection programs
Fatigue tests
Fleet survey program
Worldwide conferences
Aging fleet initiatives
707 727 737 747 727 777
707 727/737/747 757/767
747/737/727707 727 747 757 767 777 737NG
Regionalbriefings
Service entry dates707 727 747737 757767
777737NG
757-300767-400
1955 60 65 70 75 80 85 90 95 2000
Year
Page 185
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12/13/2006Filename.ppt | 185
Boeing Structural Design Standards
Page 186
Copyright © 2006 Boeing. All rights reserved.
12/13/2006Filename.ppt | 186
Service entry dates707 727 747737
777737NG
757-300767-400
1955 60 65 70 75 80 85 90 95 2000
Year
3,500
3,000
2,500
2,000
1,500
1,000
500
Number of commercial jet transports
Delivered airplanes exceeding 20 years of service
Active airplanes exceeding 20 years of service
Active airplanes exceeding design objective in hours
Delivered airplanes exceeding design objective in flights
757767
Boeing Fleet Support Actions
Page 187
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12/13/2006Filename.ppt | 187
Safety Challenge
Page 188
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12/13/2006Filename.ppt | 188
Cessna 180 - Single Load Path / Safe Life60,000 Miles of Bush Flying - Alaska;Canada;Greenland
Page 189
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12/13/2006Filename.ppt | 189
Realities of RetirementE-mail: [email protected]