Aging Airplane MaintenanceProgram Developments         1
ObjectiveTo provide information regarding the latestprogram developments to ensure the continuingstructural airworthiness ...
Contents• Background• Recent Developments  • Widespread Fatigue Damage  • Aging Airplane Safety Rule  • CPCP NPRM  • CPCP ...
Aging Airplane Concerns• As airplanes age  • Potential for fatigue cracking increases  • Corrosion may become more widespr...
Aging Fleet Issues• Economic and market conditions result in  operation of airplanes longer than anticipated• Damage on hi...
Structural Maintenance Programs• Maintenance Planning Data• Aging Airplane Programs   • Supplemental Structural Inspection...
Aging Airplane Program Developments• Widespread Fatigue Damage• Aging Airplane Safety Rule• CPCP NPRM• CPCP Reporting AMOC...
Widespread Fatigue Damage (WFD)• WFD is structural damage which is characterized by:  • The simultaneous presence of crack...
Limit of the Maintenance Program• Concept of Limit of Validity (LOV)   • Threshold beyond which the airplane     maintenan...
Aging Airplane Safety Rule (AASR)• Interim Final Rule and ACs published in Dec 2002  are result of activities called for b...
Rule Requirements, Paragraph 1• Records Reviews   • Periodic review of maintenance records based    on airplane age   • In...
Records Review – Part 1• On 8 Dec 2003, for airplanes   • Exceeding 24 years in service, 1st records      review must occu...
Records Review- Part 2• Physical inspection of the airplane either by FAA  Administrator or Designee   • Accomplished in c...
Rule Requirements, Paragraph 2• Supplemental Inspections  • Require a damage tolerance based    maintenance program by 5 D...
Supplemental Inspection• A damage tolerance based program must be in  place and operating with three elements which:   • P...
Supplemental Inspections• For all Boeing products, programs will exist• Pre-amendment 45 airplanes   • Service Action Requ...
Comments on Rule• Operators commented that existing Aging Airplane  Programs provide means of compliance  • FAA has interp...
Other FAA Issues• SSID programs on some 737, 747 models and  MD-80 have yet to be mandated• Unknown number of “major” repa...
FAA SSID AD Standardization Review• Public meeting on 27 Feb 2003  • FAA SSID Team made 8 recommendations,    including   ...
Effect on Boeing Models – Post-Amdt 45• 757, 767, 777, 737-700C/900, MD-11, MD-90, 717   • Certification basis fulfills in...
Effect on Boeing Models – Pre-Amdt 45• 707, 720, 727, 737-100 through –800*, 747-100  through -400, DC-8, DC-9, MD-80, DC-...
CPCP Reporting AMOC• CPCP ADs required quarterly reporting of Level 2  and follow-up of Level 3 reporting on a quarterly  ...
CPCP NPRM• Released in Federal Register 3 Oct 2002• Requires implementation of an FAA approved  CPCP within 2 years of rul...
Summary• Maintain continued airworthiness with   • An effective scheduled maintenance program   • Compliance with all mand...
2003 Structures Conference   Service Engineering                                  Damage                                 T...
Objective        Provide a status of regulatory changes and        Boeing’s support for damage tolerance based        insp...
Contents    • Background    • Requirements for Out-of-production Airplanes    • Requirements for In-production Airplanes  ...
Damage Tolerance Definition    • Damage tolerance is the ability to sustain        regulatory required loads in the presen...
Damage Tolerance Principles                           Ultimate load                                                       ...
Regulatory Background     • FAR 25.571 contains design certification        requirements related to fatigue and durability...
Certified Post-Amdt 45 Models     • 737 (new or modified major structure)          • -300/400/500 - engine struts         ...
Post-Amdt 45 Requirements     • Supplemental Structural Inspections        • Airworthiness Limitations Section in MPD     ...
Impact on Structural Repairs    • Post-Amdt 45 airplanes’ certification basis        requires repairs be damage tolerant  ...
Certified Pre-Amdt 45     •   707     •   727     •   737*     •   747*     •   DC-8     •   DC-9     •   MD-80     •   DC...
Pre-Amdt 45 Airplane Requirements     • Supplemental Structural Inspections        • 707, 727, 737-100/200/200C, 747-100/2...
Pre-Amdt 45 Airplane Requirements   • Repair Assessment Program required by FARs        • 707, 727, 737, 747        • DC-8...
Damage Tolerance Assessment of Repairs     • Regulatory actions require that repairs to pre-            Amdt 45 airplanes ...
Repair Assessment Program (RAP)     • FARs effective 25 May 2000     • Applies to repairs on the fuselage pressure        ...
Applying RAP to SSID DTAs     727, 737-100/200/200C     • Repairs to fuselage skin addressed by RAP may        also affect...
SSID Inspection                   Alternate internal                   SSID inspections                     Repair        ...
FAA SSID AMOC Example                  Single RAP inspection may                  satisfy both SSID and RAP               ...
SRM DTA Data    • SRMs being revised to include updated DTA data       • Pre-Amdt 45 airplanes, 757, 767    • Chapter 51  ...
Boeing Repair DTA Assistance     • Repair advice includes damage tolerance        assessment for applicable structural ite...
Repair DTA Request Data     • When requesting a DTA, submit the following        information:         • SSI number, repair...
Summary   • Damage tolerance requirements apply to both in-       production and out-of-production airplanes   • 737 RAG a...
Widespread FatigueDamage (WFD)                     0
ObjectiveTo provide understanding of Widespread FatigueDamage (WFD) and Limit of Validity (LOV). Inaddition, review the pr...
Contents• Background• Implementation Plan• Model Specific Audit Results                                 2
Background• June 1988 - International Conference on Aging  Airplanes• Airworthiness Assurance Working Group (AAWG)  charte...
AAWG Initiatives• Mandatory Modifications• Corrosion Prevention and Control• Supplemental Structural Inspections• Maintena...
AAWG WFD Actions• Developed understanding and methodology for  addressing WFD• Identified sixteen areas susceptible to WFD...
Widespread Fatigue DamageWFD is characterized by the simultaneous presenceof cracks in multiple details that are of suffic...
Sources of WFD• Multiple Site Damage (MSD)  A source of WFD characterized by the  simultaneous presence of fatigue cracks ...
Prevention of WFD•   Consists of determining if any additional inspections and    modifications are necessary for each WFD...
Industry Implementation Plan for WFD• The Industry developed program contains two  distinct issues to be addressed  • A Li...
Limit of Validity (LOV)• LOV is an operational limit of the airplane   • Based on engineering data that supports the     m...
Caveats• For all models, an aging airplane program should  consist of:   • Mandatory Modifications   • Corrosion Preventio...
Fatigue Test Evidence for LOV•   Full scale fatigue test with or without tear down•   Full scale component tests with or w...
LOV Extension• Requires additional fatigue test evidence• Revalidation of the maintenance program   • Review of existing I...
Airplanes of Interest• Out-of-Production, Pre-amendment 45 Airplanes  • 707 All Models  • 727 All Models  • 737 (100 thru ...
Status of Audit Results• The data presented here is preliminary• FAA has been briefed                                     ...
High Flight Cycle 707/720                       LOV - 40,000 Flight Cycles                       DSO – 20,000 Flight Cycle...
707/720 Audit Findings    ISP or SMPs Less than LOV• Lap splice  • Existing ADs adequate• Fuselage frame  • Existing AD (S...
High Flight Cycle 727                      LOV - 100,000 Flight Cycles                      DSO – 60,000 Flight Cycles    ...
727 Audit Findings    ISP or SMPs Less than LOV• Lap splice lower row (airplanes L/P 850 and on)   • Existing AD adequate•...
High Flight Cycle 737                      LOV - 100,000 Flight Cycles                      DSO – 75,000 Flight Cycles    ...
737 Audit Findings    ISP or SMPs Less than LOV•   Lap splice L/P 1-291, reworked configuration    •   Existing inspection...
High Flight Cycle DC-8                      LOV - 70,000 Flight Cycles                      DSO - 25,000 Flight Cycles    ...
DC-8 Audit Findings   ISP or SMPs Less than LOV• Audit results to date (all fatigue test and fleet  information reviewed) ...
High Flight Cycle DC-9                      LOV - 110,000 Flight Cycles                      DSO - 40,000 Flight Cycles   ...
DC-9 Audit Findings     ISP or SMPs Less than LOV• Audit results (all fatigue test and fleet information  reviewed)   • On...
High Flight Cycle MD-80                      LOV - 110,000 Flight Cycles                      DSO - 50,000 Flight Cycles  ...
MD-80 Audit Findings   ISP or SMPs Less than LOV• Audit results - pending results from DC-9 review                        ...
High Flight Cycle DC-10 / MD-10                        LOV - 60,000 Flight Cycles / 150,000 Flight Hours                  ...
DC-10 / MD-10 Audit Findings   ISP or SMPs Less than LOV• Audit results (all fatigue test and fleet information  reviewed)...
High Flight Cycle 747 Classic747 Classic    LOV - 30,000 f/c / 115,000 f/h (SR 35,000 f/c)               LOVext – 35,000 f...
747 Classic Audit Results       ISP or SMPs Less than LOV•   Tension Tie, ISP at 20,000 f/c / SMP at 30,000 f/c•   7075 U ...
747 Classic Audit Results     ISP or SMPs Less than LOV• LOVEXT = 35,000 f/c or 135,000 hours   • Accomplish Mandatory Mod...
Summary• Last Aging Airplane Program addressed by  AAWG is WFD• FAA developing Part 121 Operational Rule to  require opera...
Damage RemovalDuring Structural    Repairs
ObjectivesDiscuss necessity for identification and removal ofdamage when accomplishing structural repairs.                ...
Contents• Background• Recent 747 Action• Damage Removal - SRM Guidance• Maintenance Damage• Corrosion Removal and Repair  ...
Background• Multiple findings of unremoved damage on 747  fuselage skins under tailstrike repair doublers            S- 46...
Background• Skin scratches under repair doublers                                         4
Scratches                  FatigueOriginal Skin                  Cracks
Background• Repair doublers   • Inhibit inspectability   • Reduce likelihood of     venting                               ...
Crack Growth ProfilesTypical skin crack growthoriginates from hole andprogresses along skin(hole-to-hole)                 ...
Service Bulletin 747-53A2489• Released 26 November 2002• Addresses potential skin cracks resulting from  unremoved damage ...
Other Action• No related SB activity anticipated for other  models   • Stresses are lower in potential tailstrike area• He...
Skin Assessment       6 inches                     cutoutScratches hiddenby repair doubler                                ...
Optional Repetitive Inspections• Frequent inspections until skin assessment   • Internal mid-frequency eddy current @ 250 ...
Scratch Removal• Scratches must be removed prior to measuring  against rework limits• If beyond limits, trim out damage pr...
SRM Guidance – Chapter 51                                  :                            ok for                            ...
SRM Guidance – Chapter 51                                 Defined                         its are                    e Lim...
SRM Guidance – Chapter 51                                e                            amag                      move D    ...
SRM Guidance• Allowable damage defined for each type of structure                         THE DISTANCE OF THE DAMAGE FROM ...
Maintenance Damage• Poor maintenance practices can create damage  • Tool contact – scratch/gouge     0Removal of a fillet ...
Maintenance Damage• Some mandated SBs inspect for maintenance damage• Industry recommendations have addressed maintenance ...
Cracking from Gouge    Example - Alert SB on 747 to address skin cracks from    gouges between a doubler and a lap splice ...
Maintenance Damage at Fillet SealRepair doublerremoved fromthis areaScratch marks invicinity of fillet seal
Cracking at Scribe MarkExternal viewExternal view                       Internal view                        Internal view
Corrosion Removal and Repair• Ensure complete removal of corrosion prior to  refinishing   • Trapped corrosion will contin...
Lap Splice Repair withUnremoved Corrosion
Pressure Deck Repairwith Unremoved Corrosion
Drain Paths• Ensure repairs do not obstruct drain paths   • A drain path may be a gap in a structural     assembly• Check ...
Summary• Small damage can cause cracks and require  frequent inspections  • Crack patterns resulting from damage can    va...
Charging forEngineering Services                       0
Objective• To clarify Service Engineering policy of charging  for:   • Structural Repair Approval   • Engineering Technica...
Contents• Structural Repair Approval• Work Exceeding Normal Fleet Support                                        2
Structural Repair ApprovalApplies to:   • Operators who are not operating any airplane     purchased new from Boeing and w...
Chargeable Structural RepairsInclude requests that require Boeing to:   • Conduct structural analysis to substantiate     ...
Structural Repair - CommunicationAll Operator Messages  • M-1001-00-0021, Dated 21 Dec 2000     0 Implements new charge po...
Structural Repair – Charge Criteria• Single charge of $3500 covers both the repair  and 8110-3   •   8110-3 requested at t...
Expediting Repair Approval Response• MRO / Operator has good credit with Boeing  • Provide PO number or promise date with ...
Work Exceeding Normal Fleet Support• Applies to all customers• Assistance provided with a contract• Policy has always been...
Examples of Work Requiring Contract• Issuance of multiple FAA 8110-3 forms on  previously approved repairs• On-site techni...
Contract Process Flow• Customer sends in request for assistance• Boeing determines work exceeds normal fleet  support• Boe...
SummaryStructural Repair Approval• Requests for structural repair assistance are  subject to $3500 charge, even if no 8110...
SummaryWork Beyond Normal Fleet Support• Engineering Technical Assistance will be  provided under a contractual agreement ...
Structural Health Management             (SHM)                               1
ObjectivesReduce cost of ownership and introduceon-condition structural maintenanceDevise an automated structural inspecti...
Contents• SHM Goals and Benefits• SHM Definition, Development and Technology  Status• Industry Collaboration/Engagement• S...
Potential SHM Benefits• Reduced operating cost• First step in progression to on-condition structural    maintenance•   Lon...
What is SHM?• SHM is a structural condition assessment  system using sensor technology that has  potential to locate airpl...
IVHMAHM                                                           SHM                               IVHM                  ...
IVHM Operating ConceptMaintenanceControl                              In Flight                          Portable         ...
Potential Onboard Health                   Management Hierarchy    Air/Ground       Wireless Ground        Maintenance    ...
SHM Technology Testing• Laboratory testing• In-service testing                            9
SensorsMoisture Sensor                  Damage Sensors                                   10
Accidental Damage Sensors Installed                                      Surface mounted layers• Two embedded layers• Thre...
Event and Damage DetectionSkin-Stringer Composite Barrel Demonstration                                               12
Data Logger boxesinstalled on equipment racks          Battery
Sensor installed next to stringer                                8                                                        ...
Implementation• What will it take to implement SHM?  • Correlation between SHM technology and    existing maintenance     ...
Implementation Timeline   2008                    2003Phase I• Technology  Development and  testingPhase II• Working toget...
Summary• SHM has potential to reduce airplane structural  maintenance cost• Testing and development of SHM technology in  ...
737 Lap Joints                 0
Contents• Background• Service Bulletin (SB) 737-53A1255• SB 737-53A1177, Revision 7 changes• Inspection issue• Fleet Exper...
Background• Two service bulletins currently address cracking in lap  joints on 737s:   • SB 737-53A1177, Revision 6       ...
Background        L/P 292-2565 Lap Joint Configuration      Covered by    SB 737- 53A1177          and    SB 737- 53A1255C...
Background   SB 737-53A1177, Rev 6 Repair Locations        STA     STA    STA           STA       STA   STA       259.50  ...
BackgroundSB 737-53A1177, Rev 6 Inspection Locations        STA   STA         STA          STA            STA       STA   ...
SB 737-53A1255•   Two recent fleet findings have increased concern with    extent of lower row cracking     • 23-inch link...
Crack Locations        STA       STA           STA                   STA             STA     STA       259.50     360     ...
Over Wing Cracking
Close up of DamageSeveredStringer Clip                Cracks
SB 737-53A1255• Alert SB released 17 Oct 2002• FAA reviewing for possible rulemaking• Inspection directed at unmodified ai...
Inspection Details•   One-time inspection program with tiered approach    based on cycles and extent of findings     • Ove...
Over Wing Inspection LocationsInspect S-4L and S-4R Lap                                                  StringerJoint and...
Fleet Inspection Results• Records indicate 35 airplanes have been inspected   • 20 over 50,000 f/c   • 15 between 45,000 a...
Proposed Revision 7 Changes• Compliance related to SB 737-53A1255  inspection results• Additional repair information for 7...
Proposed Revision 7 Changes• Compliance changes may result from data  gathered from SB 737-53A1255 inspections  • Data is ...
Proposed Changes: 737-200C• Rev 6 has incomplete repair information for S-4R  and S-10R between BS360 and BS540   • Instru...
Proposed Changes: 737-300/400/500• 737 –300 repair drawings are incomplete   • Unique structure not covered on drawings   ...
Current Window Belt Recommendations•   Accomplish inspections of 3 fasteners in corners    common to window frame at 50,00...
Rev 6 Window Corner Inspections          Rev 6 Inspection Locations                                       19
Rev 6 Window Corner Experience• Cracks reported deviating from Rev 6  instructions   • Common to skin/bonded doubler along...
Rev 7 Window Corner Inspections          Rev 6 Inspection Locations          New Rev 7 Inspection Locations               ...
Proposed Window Corner Changes• Additional inspections and/or rework may be  necessary for airplanes inspected per Rev 6  ...
Proposed Window Corner Changes• Data package will be provided to operators in mid  2003, in advance of Rev 7   • Revised i...
Inspection Issue• Alodine (conversion) coated rivets replaced  anodized coated rivets      0Phased into production 1985-19...
Anodize vs. Alodine RivetsConsistently long             Inconsistent short rivetrivet signals                 signals with...
Inspection Issue• Method to identify type of coating on installed  rivets under study   • Existing sliding probe inspectio...
Fleet Experience• Approximately 155 airplanes modified to date   • 134 737-200/-200Cs   • 21 737-300s      0140 have accom...
Rulemaking• Three ADs issued against Rev 6 effective 17 May 2002   • AD 2002-07-08: Lap joint cutout repair at 50,000 f/c,...
Summary• Two recent fleet findings have increased concern    with extent of lower row cracking     • One-time SB 737-53A12...
2003 Structures ConferenceService Engineering                                Nondestructive                               ...
ObjectivesIncrease awareness of Nondestructive Testing(NDT) training and certification options, that canpromote better ins...
Contents• Background• Options for Training and Certification• FAA Guidelines• CAA/European Requirements                   ...
Background• Increasing reliance on NDT detecting smaller cracks   • Improper inspection evaluation has caused    additiona...
Incorrect Evaluation Result                                Assumed                                crack                   ...
Example of Missed Cracks                           6
Options• Select a training and / or certification program   • Central certification - external agency   • Local training -...
Central Certification Programs• USA  • ASNT Level III Certification• Europe  • EN 473 equivalent for each country• Canada ...
Internal Airline/MRO  Training and Certification Programs• USA standards  • AIA-NAS 410 Draft to combine with EN 4179    (...
FAA Advisory Circular Pending• Requires documented education, training and  experience• Recognizes standards / specificati...
European Standards• EN standards• Internal and external specifications   • Three levels of competence   • Documented educa...
Summary• Controlled NDT training and certification reduces  false and missed indications• Meet a recognized standard that ...
737 ClassicFuselage Issues                  0
ObjectiveProvide overview of 737 Classic fuselagestructural issues that may be subject offuture FAA rulemaking.           ...
Contents• Existing Service Bulletin Recommendations• New In-Service Findings• New or Revised Boeing Recommendations• FAA A...
737 Classic Fuselage Issues                 SB 737-53-1216Frame Cracks                      Between S-8 and S-9SB 737-53A1...
Cracked Frames Above S-14                            SB 737-53-1125                            Frame Cracks               ...
Cracked Frames Above S-14Existing Recommendations• SB 737-53-1125, Rev 2 released Nov 1991   • Addresses fatigue cracking ...
Cracked Frames Above S-14In-Service Findings• Severed BS 747 frame and a 1.3 inch crack in   adjacent BS 767 frame at same...
Cracked Frames Above S-14                  Frame Cracks Start At End                  Fastener Common to Splice           ...
Cracked Frames Above S-14• New Recommendations   • SB 737-53-1125 to be revised and upgraded to Alert    status      0Init...
Frame Cracks Between S-8 and S-9    SB 737-53-1216     Frame Cracks  Between S-8 and S-9                                   9
Frame Cracks Between S-8 and S-9• Existing Recommendations   • No Service Bulletin• In-Service Findings   • Numerous crack...
Frame Cracks Between S-8 and S-9                                   11
Frame Cracking between S-8 and S-9• New Recommendations   • New 737-53-1216 SB to be released mid 2003      0Effective L/P...
Skin Cracks at Chem-mill StepsSB 737-53A1210 and 737-53A1234 Skin Cracks at Chem-mill Steps                               ...
Skin Cracks at Chem-mill Steps• Existing Recommendations   • SB 737-53A1210, Rev 1 released Oct 2001     0Addresses cracki...
Skin Cracks at Chem-mill Steps• Existing Recommendations   • SB 737-53A1210, Rev 1 released Oct 2001     0Section 41 and a...
Skin Cracks at Chem-mill Steps• Existing Recommendations   • SB 737-53A1234 released June 2002       0 Testing predicts cr...
Skin Cracks at Chem-mill Steps                              Crack at                              Chem-mill Step          ...
Skin Cracks at Chem-mill Steps• In-Service Findings: SB 737-53A1210   • Numerous cracks along edge of chem-milled    pocke...
Skin Cracks at Chem-mill Steps• Recommendations   • SB 737-53A1210 to be revised     0Reduce thresholds for initial visual...
Forward Cargo Door Beam CracksSB 737-52A1149Fwd Cargo Door#4 Beam Cracks                                    20
Forward Cargo Door Beam Cracks• Existing Recommendations   • SB737-52A1100, Rev 4 released Mar 2001     0Addresses crackin...
Forward Cargo Door # 4 Beam Cracks                 #4 Cross Beam                                 Typical Crack            ...
Forward Cargo Door # 4 Beam Cracks• In-Service Findings   • Four operators reported cracking in #4 stop    beam      0Root...
Forward Cargo Door Beam Cracks• New Recommendations   • Release SB737-52-1149 in late 2003      0Will provide inspection, ...
Lap Joint Corrosion and Cracking        SB 737-53A1224Lap Joint Lower Cracking: 1-291                                     ...
Lap Joint Corrosion and Cracking• Existing Recommendations   • AD 2000-17-04 mandated original inspection program   • SB 7...
Lap Joint Corrosion and Cracking                  Upper skinCracks in lowerfastener rowCovered bySB 737-53A1224           ...
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Slides from 2003 structures conference

  1. 1. Aging Airplane MaintenanceProgram Developments 1
  2. 2. ObjectiveTo provide information regarding the latestprogram developments to ensure the continuingstructural airworthiness of airplanes as they age. 2
  3. 3. Contents• Background• Recent Developments • Widespread Fatigue Damage • Aging Airplane Safety Rule • CPCP NPRM • CPCP Reporting AMOC 3
  4. 4. Aging Airplane Concerns• As airplanes age • Potential for fatigue cracking increases • Corrosion may become more widespread and significantly degrade fatigue performance• Two or more types of damage in an area can degrade fail-safe or damage tolerance capability 4
  5. 5. Aging Fleet Issues• Economic and market conditions result in operation of airplanes longer than anticipated• Damage on high time airplanes highlighted aging fleet structural concerns • Horizontal stabilizer • Fuselage skin• Maintenance programs for an aging fleet must address effects of fatigue and corrosion during long term operations 5
  6. 6. Structural Maintenance Programs• Maintenance Planning Data• Aging Airplane Programs • Supplemental Structural Inspections • Corrosion Prevention and Control Program • Mandatory modifications and inspections • Repair Assessment Program • Widespread Fatigue Damage Program (TBD)• Service Bulletins• Other mandated actions 6
  7. 7. Aging Airplane Program Developments• Widespread Fatigue Damage• Aging Airplane Safety Rule• CPCP NPRM• CPCP Reporting AMOC 7
  8. 8. Widespread Fatigue Damage (WFD)• WFD is structural damage which is characterized by: • The simultaneous presence of cracks at multiple structural details, and • Have sufficient size and density such that the structure will no longer meet its damage tolerance requirement• There is a point in airplane operation where the risk of uncertainties in structural performance and the probable development of WFD increases 8
  9. 9. Limit of the Maintenance Program• Concept of Limit of Validity (LOV) • Threshold beyond which the airplane maintenance program is not considered valid• WFD requirements to be provided in model specific documents • LOV • Inspections • Modifications 9
  10. 10. Aging Airplane Safety Rule (AASR)• Interim Final Rule and ACs published in Dec 2002 are result of activities called for by the “Aging Aircraft Safety Act of 1991” • Rule result of comments received from two previous NPRM publications • Further comments requested because 1999 NPRM was significantly modified • Comment period extended to 5 May 2003• Airplanes operated under FARs 121, 129, and 135• Effective 8 Dec 2003 10
  11. 11. Rule Requirements, Paragraph 1• Records Reviews • Periodic review of maintenance records based on airplane age • Inspections of airplanes • Focus on existing aging aircraft requirements• Specified in FARs 121.368, 129.33 and 135.422 11
  12. 12. Records Review – Part 1• On 8 Dec 2003, for airplanes • Exceeding 24 years in service, 1st records review must occur before 5 Dec 2007 • Exceeding 14 years in service but less than 24 years, 1st records review must occur before 4 Dec 2008 • Less than 14 years in service, no later than 5 years after the start of 15th year in service • For all airplanes, records review will be repeated every 7 years thereafter 12
  13. 13. Records Review- Part 2• Physical inspection of the airplane either by FAA Administrator or Designee • Accomplished in conjunction with the maintenance records review• Administrator will require notification 60 days prior to date that airplane and its records will be available for inspection 13
  14. 14. Rule Requirements, Paragraph 2• Supplemental Inspections • Require a damage tolerance based maintenance program by 5 Dec 2007 • Affects airplanes operated under FAR 121, 129, and 135 14
  15. 15. Supplemental Inspection• A damage tolerance based program must be in place and operating with three elements which: • Proactively inspects for damage to the as delivered structure to maintain continued airworthiness* • Maintains continued airworthiness of a repaired airplane • Establishes a new or revised program for areas of the airplane that undergo major modification *Repairs to areas affected by the SSID or ALI require damage tolerance based maintenance programs 15
  16. 16. Supplemental Inspections• For all Boeing products, programs will exist• Pre-amendment 45 airplanes • Service Action Requirements • CPCP • SSIP • Repair Assessment Program 0Fuselage pressure boundary• Post Amendment 45 airplanes • Certification basis requirement 16
  17. 17. Comments on Rule• Operators commented that existing Aging Airplane Programs provide means of compliance • FAA has interpreted additional issues and responses that operators “must establish damage-tolerance-based SSIPs or service- history-based SSIPs, as applicable, for major repairs, major alterations, and modifications to structures not affected by the repair assessment program, such as fuselage frames and longerons, and wing and empennage structures” 17
  18. 18. Other FAA Issues• SSID programs on some 737, 747 models and MD-80 have yet to be mandated• Unknown number of “major” repairs and modifications that may now require damage tolerance based inspections • Service Bulletins • STCs 18
  19. 19. FAA SSID AD Standardization Review• Public meeting on 27 Feb 2003 • FAA SSID Team made 8 recommendations, including 0Assessment compliance time to 18 months 0Three step assessment process • Relationship between SSID ADs and AASR • Requirements for repairs, alterations and modifications under these regulations 0Have damage tolerance based inspections 19
  20. 20. Effect on Boeing Models – Post-Amdt 45• 757, 767, 777, 737-700C/900, MD-11, MD-90, 717 • Certification basis fulfills intent of the AASR for damage tolerance based maintenance programs 0All have SSIPs in form of Airworthiness Limitation Instructions (certain models have ADs for early L/Ps) 0All require damage tolerance based repairs and modifications 20
  21. 21. Effect on Boeing Models – Pre-Amdt 45• 707, 720, 727, 737-100 through –800*, 747-100 through -400, DC-8, DC-9, MD-80, DC-10 • Required by FARs to have a RAP 0Applicable only to fuselage pressure boundary • Rule will require additional damage tolerance based inspection program for structures not addressed by RAP * Except 737-700C 21
  22. 22. CPCP Reporting AMOC• CPCP ADs required quarterly reporting of Level 2 and follow-up of Level 3 reporting on a quarterly basis• Corrosion reporting also required per FAR 121.703• Boeing proposed that reporting corrosion per FAR 121.703 would fulfill the AD reporting requirements• FAA concurred and issued an AMOC • Separate reporting to Boeing no longer required 22
  23. 23. CPCP NPRM• Released in Federal Register 3 Oct 2002• Requires implementation of an FAA approved CPCP within 2 years of rule effective date • Applicable to FAR 121, 129 and 135 operators • Baseline program to control corrosion so that damage does not exceed Level 1 • Existing CPCPs will satisfy rule• Comment period closed 1 Apr 2003 23
  24. 24. Summary• Maintain continued airworthiness with • An effective scheduled maintenance program • Compliance with all mandated actions• New rules are being established to apply damage tolerance and corrosion programs to more of the transport airplane fleet• Maintenance program must be valid for extended operations• Structural maintenance activities will increase as airplanes age 24
  25. 25. 2003 Structures Conference Service Engineering Damage Tolerance Programs Update 13/12/2003
  26. 26. Objective Provide a status of regulatory changes and Boeing’s support for damage tolerance based inspection programs for in-production and out-of-production airplanes 23/12/2003
  27. 27. Contents • Background • Requirements for Out-of-production Airplanes • Requirements for In-production Airplanes • Effects on Repairs 33/12/2003
  28. 28. Damage Tolerance Definition • Damage tolerance is the ability to sustain regulatory required loads in the presence of damage until that damage is detected and is repaired 43/12/2003
  29. 29. Damage Tolerance Principles Ultimate load Ultimate load capability Deterioration due to restored after repair Structural Strength undetected damage Damage detection and restoration FAR 25.571 load requirement Normal operating loads Detection Period of service period 53/12/2003
  30. 30. Regulatory Background • FAR 25.571 contains design certification requirements related to fatigue and durability • Amendment 45 added requirements for structural damage tolerance analysis • Evaluate new structures on airplanes certified after 1978 • Establish inspections to ensure timely detection of damage before structural capability is degraded below regulatory prescribed limits • Advisory Circular 91-56 issued in 1981 • Airplanes certified prior to Amdt 45 needed a structural integrity program 0 SSID / SIP created as alternative to service life limits 63/12/2003
  31. 31. Certified Post-Amdt 45 Models • 737 (new or modified major structure) • -300/400/500 - engine struts • -600/700/800 - engine struts and wing structure • 737-700C/900 entire airframe • 747-400 strut-to-wing attach structure • 757 • 767 • 777 • MD-11 • MD-90 • 717 73/12/2003
  32. 32. Post-Amdt 45 Requirements • Supplemental Structural Inspections • Airworthiness Limitations Section in MPD 0737-700C/900, 757, 767, 777 0737-600/700/800 • L/P 1 – 714 subject to FAA rulemaking • L/P 715 and on per Type Certificate Data Sheet • Airworthiness Limitations Instructions (ALI) in MRB report 0MD-11, MD-90, 717 • Selected structural details to be inspected at specified thresholds 83/12/2003
  33. 33. Impact on Structural Repairs • Post-Amdt 45 airplanes’ certification basis requires repairs be damage tolerant • Supplemental inspections may be required to maintain damage tolerance characteristics • Repairs to original PSE structure may interfere with an existing MPD inspection • Requires a damage tolerance assessment (DTA) • Repair assessment inherent in repair design requirements 93/12/2003
  34. 34. Certified Pre-Amdt 45 • 707 • 727 • 737* • 747* • DC-8 • DC-9 • MD-80 • DC-10 * Except for structures added or modified after 1978 103/12/2003
  35. 35. Pre-Amdt 45 Airplane Requirements • Supplemental Structural Inspections • 707, 727, 737-100/200/200C, 747-100/200 (SSID) • DC-8, DC-9, MD-80, DC-10 (SID) 0 Threshold based programs 0 Mandated by ADs • Recent developments • 737-300/400/500 SSID at FAA for approval • 747 SSID revised (Rev. G) 0 Added –300/400/SR models 0 Eliminated candidate fleet 0 Approved as an AMOC to AD 94-15-18 113/12/2003
  36. 36. Pre-Amdt 45 Airplane Requirements • Repair Assessment Program required by FARs • 707, 727, 737, 747 • DC-8, DC-9, MD-80, DC-10 • Recent developments • 737 RAP document Rev. C adds -300/400/500 models 0 Approved by FAA Feb 2003 123/12/2003
  37. 37. Damage Tolerance Assessment of Repairs • Regulatory actions require that repairs to pre- Amdt 45 airplanes be evaluated for damage tolerance effects • 707,727, 737 Classic, 747, DC-8, DC-9, MD-80, DC-10 • Repairs to SSID / SIP structures • Fuselage pressure vessel boundary • DTA results will establish if alternate inspections are required to maintain damage tolerance characteristics 133/12/2003
  38. 38. Repair Assessment Program (RAP) • FARs effective 25 May 2000 • Applies to repairs on the fuselage pressure vessel boundary • Guidelines documents provide procedures to assess effect of repairs on damage tolerance of original structure • Operators incorporate into maintenance programs • Assessment threshold is 75% DSO 143/12/2003
  39. 39. Applying RAP to SSID DTAs 727, 737-100/200/200C • Repairs to fuselage skin addressed by RAP may also affect a SSID item • RAP evaluation results can also fulfill SSID DTA requirements • Boeing submitted a proposal for application of RAG inspections to repairs of specific SSID Items • FAA issued letter allowing RAG documents as AMOCs to paragraphs (e) and (g) of SSID ADs 153/12/2003
  40. 40. SSID Inspection Alternate internal SSID inspections Repair Bearstrap Doubler HF EC EC Skin HF VI SU EC LFEC AL LF External RAP Inspection FAA previously required continued SSID inspection of entire detail 163/12/2003
  41. 41. FAA SSID AMOC Example Single RAP inspection may satisfy both SSID and RAP requirements Repair Bearstrap Doubler Skin VI SU EC AL LFEC LF External RAP inspection 173/12/2003
  42. 42. SRM DTA Data • SRMs being revised to include updated DTA data • Pre-Amdt 45 airplanes, 757, 767 • Chapter 51 • Definitions 0 Category of repairs • Chapters 52 through 57 • Supplemental inspection requirements included for specific repairs 0 Alternate SSID / SIP item inspections 0 RAP related inspections (Pre-Amdt 45 airplanes) 183/12/2003
  43. 43. Boeing Repair DTA Assistance • Repair advice includes damage tolerance assessment for applicable structural items • PSEs / SSIs on post-Amdt 45 certified airplanes • SSID structures on pre-Amdt 45 certified airplanes only when requested • Response provided within 12 months of repair date 193/12/2003
  44. 44. Repair DTA Request Data • When requesting a DTA, submit the following information: • SSI number, repair/modification details and date of installation • Details preventing compliance of SSID requirements • A drawing of the accomplished repair 0 Include cross sectional sketch of the repair • Exact location of the repair doubler(s) • Thickness and material of the doubler(s) • Fastener types, pitch and edge margins • Airplane identification • Total flight cycles 203/12/2003
  45. 45. Summary • Damage tolerance requirements apply to both in- production and out-of-production airplanes • 737 RAG and 737/747 SSIDs recently revised • Damage Tolerance Assessment of repairs has become a major concern for operators 213/12/2003
  46. 46. Widespread FatigueDamage (WFD) 0
  47. 47. ObjectiveTo provide understanding of Widespread FatigueDamage (WFD) and Limit of Validity (LOV). Inaddition, review the preliminary LOV for each Out-of-Production, Pre-amendment 45 Boeing modelpresented here. 1
  48. 48. Contents• Background• Implementation Plan• Model Specific Audit Results 2
  49. 49. Background• June 1988 - International Conference on Aging Airplanes• Airworthiness Assurance Working Group (AAWG) chartered • Comprised of members representing the FAA/JAA, OEMs, and Operators • Established six initiatives to develop maintenance standards for aging airplanes 3
  50. 50. AAWG Initiatives• Mandatory Modifications• Corrosion Prevention and Control• Supplemental Structural Inspections• Maintenance Programs Guidelines• Pressure Boundary Repair Assessment• Prevention of Widespread Fatigue Damage (WFD) 4
  51. 51. AAWG WFD Actions• Developed understanding and methodology for addressing WFD• Identified sixteen areas susceptible to WFD• Requested OEM audits of each model for WFD• Drafted proposed NPRM and AC for FAR 121 operational rule 5
  52. 52. Widespread Fatigue DamageWFD is characterized by the simultaneous presenceof cracks in multiple details that are of sufficientsize and density whereby the structure will nolonger meet damage tolerance requirements (i.e.,maintain regulatory required residual strength afterpartial structural failure). 6
  53. 53. Sources of WFD• Multiple Site Damage (MSD) A source of WFD characterized by the simultaneous presence of fatigue cracks in the same structural element• Multiple Element Damage (MED) A source of WFD characterized by the simultaneous presence of fatigue cracks in similar adjacent structural elements 7
  54. 54. Prevention of WFD• Consists of determining if any additional inspections and modifications are necessary for each WFD susceptible structural location• Inspection Start Point (ISP) • Point when special inspections of the fleet are initiated due to probability of having a specific MSD/MED condition• Structural Modification Point (SMP) • Point reduced from WFD average behavior, so that operation up to that point provides equivalent protection to that of a two-lifetime fatigue test • No airplane may be operated beyond SMP without modification or part replacement 8
  55. 55. Industry Implementation Plan for WFD• The Industry developed program contains two distinct issues to be addressed • A Limit of Validity (LOV) of the Maintenance Program • Maintenance program adjustments (ISPs and SMPs) to ensure WFD will be prevented from occurring within the LOV of the maintenance program 9
  56. 56. Limit of Validity (LOV)• LOV is an operational limit of the airplane • Based on engineering data that supports the maintenance program • All identified service actions are required for operation up to LOV• Established on the basis of fatigue test evidence• Point where there is significantly increased risk of uncertainties in structural performance and probable development of WFD 10
  57. 57. Caveats• For all models, an aging airplane program should consist of: • Mandatory Modifications • Corrosion Prevention and Control • Repair Assessment Program • Supplemental Structural Inspections• All known structural airworthiness issues, including WFD, should be recognized and service actions initiated 11
  58. 58. Fatigue Test Evidence for LOV• Full scale fatigue test with or without tear down• Full scale component tests with or without tear down• Tear down and refurbishment of a high time airplane• Less than full scale component tests• Fleet demonstrated lives• Evaluation of in-service problems experienced by other airplanes with similar design concepts• Analysis methods which have been parametrically developed to reflect fatigue test and service experience 12
  59. 59. LOV Extension• Requires additional fatigue test evidence• Revalidation of the maintenance program • Review of existing ISPs and SMPs • Possible development of new ISP and SMPs 13
  60. 60. Airplanes of Interest• Out-of-Production, Pre-amendment 45 Airplanes • 707 All Models • 727 All Models • 737 (100 thru 500) • 747 (100, 200, 300, SP) • DC-8 • DC-9, MD-80 • DC-10, MD-10• Other models will be addressed later 14
  61. 61. Status of Audit Results• The data presented here is preliminary• FAA has been briefed 15
  62. 62. High Flight Cycle 707/720 LOV - 40,000 Flight Cycles DSO – 20,000 Flight Cycles 35Number of Airplanes 30 25 20 15 10 5 0 21 23 25 27 29 31 33 35 37 39 Flight Cycles (1000) Data as of 11/2002 16
  63. 63. 707/720 Audit Findings ISP or SMPs Less than LOV• Lap splice • Existing ADs adequate• Fuselage frame • Existing AD (SSID) - satisfy ISP requirements• Analytical results for wing and empennage show no ISPs below LOV 17
  64. 64. High Flight Cycle 727 LOV - 100,000 Flight Cycles DSO – 60,000 Flight Cycles 12Number of Airplanes 10 8 6 4 2 0 59 61 63 65 67 69 71 73 75 77 79 81 83 85 87 Flight Cycles (1000) 18
  65. 65. 727 Audit Findings ISP or SMPs Less than LOV• Lap splice lower row (airplanes L/P 850 and on) • Existing AD adequate• Fuselage frame (test finding) • ISP 42,800 flights • SB in work– Schedule TBD – possible FAA rulemaking• Stringer-to-crown skin (test finding) • ISP 61,000 flights • SB due out mid 2003 – possible FAA rulemaking• Analytical results for wing and empennage show no ISPs below LOV 19
  66. 66. High Flight Cycle 737 LOV - 100,000 Flight Cycles DSO – 75,000 Flight Cycles 737-200 Line # 1 - 291 737-200 Line # 292 and on 16 14Number of Airplanes 12 10 8 6 4 2 0 75K 77K 79K 81K 83K 85K 87K 89K 91K 93K 95K 97K Flight Cycles 20
  67. 67. 737 Audit Findings ISP or SMPs Less than LOV• Lap splice L/P 1-291, reworked configuration • Existing inspection AD adequate • Anticipated new AD on modification• Lap splice lower row airplanes L/P 292 to 2565 – Unmodified • Existing AD adequate• Lap modification re-inspection L/P 292-2565 • ISP - 45,000 flights after installation 0Existing AD adequate• Analytical results for wing and empennage show no ISPs below LOV 21
  68. 68. High Flight Cycle DC-8 LOV - 70,000 Flight Cycles DSO - 25,000 Flight Cycles 90 80NUMBER OF AIRPLANES 70 60 50 40 30 20 10 0 10K 15K 20K 25K 30K 35K 40K 45K 50K 55K Flight Cycles 22
  69. 69. DC-8 Audit Findings ISP or SMPs Less than LOV• Audit results to date (all fatigue test and fleet information reviewed) • Two areas of concern: 0Aft fuselage longitudinal splice • ISP TBD • SMP TBD 0Wing chordwise splice • ISP TBD • SMP TBD 23
  70. 70. High Flight Cycle DC-9 LOV - 110,000 Flight Cycles DSO - 40,000 Flight Cycles 80 70NUMBER OF AIRPLANES 60 50 40 30 20 10 0 40K 45K 50K 55K 60K 65K 70K 75K 80K 85K 90K 95K 100K 105K Flight Cycles 24
  71. 71. DC-9 Audit Findings ISP or SMPs Less than LOV• Audit results (all fatigue test and fleet information reviewed) • One area of concern: 0 Transverse skin joint at aft pressure bulkhead • Prior in-service issue • Requires additional review 0 ISP and SMP TBD 25
  72. 72. High Flight Cycle MD-80 LOV - 110,000 Flight Cycles DSO - 50,000 Flight Cycles 300 280NUMBER OF AIRPLANES 240 200 160 120 80 40 0 0K 5K 10K 15K 20K 25K 30K 35K 40K 45K 50K 55K Flight Cycles 26
  73. 73. MD-80 Audit Findings ISP or SMPs Less than LOV• Audit results - pending results from DC-9 review 27
  74. 74. High Flight Cycle DC-10 / MD-10 LOV - 60,000 Flight Cycles / 150,000 Flight Hours DSO - DC-10-10 42,000 Flight Cycles DC-10-30/-40, MD-10 30,000 Flight Cycles 100NUMBER OF AIRPLANES 80 60 40 20 0 5K 10K 15K 20K 25K 30K 35K 40K 45K Flight Cycles 28
  75. 75. DC-10 / MD-10 Audit Findings ISP or SMPs Less than LOV• Audit results (all fatigue test and fleet information reviewed) • One area of concern: 0Possible frame area • Lower section near cargo floor beams • Multiple frames in a row • Failed during fatigue tests • Still investigating • Preliminary ISP < 30,000 flights 0ISP and SMP TBD 29
  76. 76. High Flight Cycle 747 Classic747 Classic LOV - 30,000 f/c / 115,000 f/h (SR 35,000 f/c) LOVext – 35,000 f/c (SR 40,000 f/c)DSO - 20,000 Flights / 60,000 Hours (SP, SR variable) 12 Number of Airplanes 10 8 6 -SR 4 -100/-200/-200F 2 0 24000 26000 28000 30000 32000 34000 36000 Flight Cycles 30
  77. 77. 747 Classic Audit Results ISP or SMPs Less than LOV• Tension Tie, ISP at 20,000 f/c / SMP at 30,000 f/c• 7075 U D Floor Beams (at floor panel holes), SMP at 23,000 f/c• 2024 U D Floor Beams, SMP at 30,000 f/c• Lower Lobe Frame, ISP = 14,000 f/c• Stringer 44 Skin Lap Splice, SMP = 30,000 f/c• Other Lap Splices < 0.071” Thick, ISP = 26,000 f/c• Aft Pressure Bulkhead Web Splices, ISP = 28,000 f/c• Frames Section 41 (redesigned frames), ISP = 30,000 f/c• Circumferential Skin Splices, ISP = 25,000 f/c 31
  78. 78. 747 Classic Audit Results ISP or SMPs Less than LOV• LOVEXT = 35,000 f/c or 135,000 hours • Accomplish Mandatory Modifications of all remaining WFD audit findings at 30,000 f/c • Perform limited teardowns and refurbishments at LOV (wing, stabilizer, circumferential splices) • Incorporate additional identified SBs • SSID Rev. G (unless already incorporated)• Actions necessary to raise LOVEXT • Fatigue test and teardown of airframe with all mandated modifications 32
  79. 79. Summary• Last Aging Airplane Program addressed by AAWG is WFD• FAA developing Part 121 Operational Rule to require operators to adjust maintenance in order to preclude WFD • Introduces concept of LOV • May have additional inspections and structural modifications at locations susceptible to WFD• Boeing conducted WFD audits of Post Production, Pre Amdt 25-45 airplanes and established LOVs 33
  80. 80. Damage RemovalDuring Structural Repairs
  81. 81. ObjectivesDiscuss necessity for identification and removal ofdamage when accomplishing structural repairs. 1
  82. 82. Contents• Background• Recent 747 Action• Damage Removal - SRM Guidance• Maintenance Damage• Corrosion Removal and Repair 2
  83. 83. Background• Multiple findings of unremoved damage on 747 fuselage skins under tailstrike repair doublers S- 46L & S- 46R STA 2360 STA 1961 3
  84. 84. Background• Skin scratches under repair doublers 4
  85. 85. Scratches FatigueOriginal Skin Cracks
  86. 86. Background• Repair doublers • Inhibit inspectability • Reduce likelihood of venting Pressure Repair Doubler keeps skin from moving outboard when pressurized Potential skin crack location 6
  87. 87. Crack Growth ProfilesTypical skin crack growthoriginates from hole andprogresses along skin(hole-to-hole) Limited crack length detectable by visual and HFECSkin crack growth originatingfrom longitudinal scratchinitiates from surface andprogresses through thickness Visual and HFEC only detects cracks when fully through thickness 7
  88. 88. Service Bulletin 747-53A2489• Released 26 November 2002• Addresses potential skin cracks resulting from unremoved damage at tailstrike repairs • Tailstrike events can result in long, longitudinal scratches• Immediately adopted AD 2003-03-19 effective 20 February 2003 • Initial inspection prior to later of 21 May 2003 or 15,000 f/c 8
  89. 89. Other Action• No related SB activity anticipated for other models • Stresses are lower in potential tailstrike area• Heightened awareness of skin scratches among regulatory and investigative authorities 9
  90. 90. Skin Assessment 6 inches cutoutScratches hiddenby repair doubler External detailed visual Remove and tactile doubler inspection 10
  91. 91. Optional Repetitive Inspections• Frequent inspections until skin assessment • Internal mid-frequency eddy current @ 250 f/c or • External ultrasonic (UT) @ 250 f/c Internal MFEC Reliably detectSkin cracking whenDoubler External UT 50% through thickness Potential cracks 11
  92. 92. Scratch Removal• Scratches must be removed prior to measuring against rework limits• If beyond limits, trim out damage prior to repair • No allowance for blending and then installing typical skin repairs• For pressurized fuselage – pay particular attention to long, longitudinally oriented scratches 12
  93. 93. SRM Guidance – Chapter 51 : ok for Abrasion What to Lo Corrosion n Crack sc riptio Ab rief de damage Crease of of types Delamination Dent Disbond (12) Scratch: A line of damage in the Gouge material where the result is a Hole cross-sectional area change. This damage is usually caused Nick by contact with a sharp object. Puncture Scratch 13
  94. 94. SRM Guidance – Chapter 51 Defined its are e Lim Wher work in re its for 57 able lim rough Allow rs 52 th te Chap 3. Allowable Damage A. Make sure that you refer to the applicable allowable damage chapter-section-subject in Chapter 52 thru 57 of this structural repair manual for the rework limits and the necessary shot peening data 14
  95. 95. SRM Guidance – Chapter 51 e amag move D How to Re or f pe ctions able and ins thin allow Me thods at is wi th da mage limits 4. Procedures to Remove Nicks, Scratches and Gouges A. Aluminum Metal Alloys Includes acceptable abrasives, NDI inspection requirements, and protective treatments 15
  96. 96. SRM Guidance• Allowable damage defined for each type of structure THE DISTANCE OF THE DAMAGE FROM AN EXISTING HOLE, FASTENERS OR SKIN EDGE MUST NOT BE LESS THAN 20X 20X ROUND OUT TO 1.00R MIN MIN AND TAPER AS SHOWN X = DEPTH OF CLEAN UP SECTION A-A Depth and length of allowed material removal defined Includes restrictions such as distance from fasteners (above) 16
  97. 97. Maintenance Damage• Poor maintenance practices can create damage • Tool contact – scratch/gouge 0Removal of a fillet seal • Removal of a doubler – scratch/gouge • Not replacing removal of CICs - corrosion • Blocking drain paths - corrosion 17
  98. 98. Maintenance Damage• Some mandated SBs inspect for maintenance damage• Industry recommendations have addressed maintenance issues NTSB to FAA: PAMA Article FAA published “Issue maintenance an Advisory PMI Action Notice bulletin to all Circular and two manufacturers, AC 43-16, #145 articles to inform AIRCRAFT SKIN DAMAGE Principle airlines… that In two separate incidents, one in early 1987 and again in late 1988, air carrier aircraft experienced pressurized skin ruptures and associated explosive decompression. In both cases, the probable cause of the pressurized skin rapture has been determined to Maintenance be skin cracking along stress concentrations generated by scratches on the aircraft skin. informs them of Examination by the National Transportation Safety Board (NTSB) has resolved that these scratches were caused by improper marking of the skin by maintenance personnel performing structural repairs. Pressurized General Aviation aircraft can also be adversely affected by similar Inspectors and these incidents,… improper maintenance practices. Although aviation mechanics are provided information concerning the proper handling and marking of materials used in the construction and repair of aircraft, these incidents have generated a concern that maintenance personnel may unknowingly damage stressed or load carrying structure by using improper tools, equipment, methods, or by improper/careless use of the correct tools, industry of the Direct all PMIs to equipment, or methods. Scratches or sharp dents are very susceptible to cracking in service, possibly at a time when the failure of the part will be catastrophic. Scratches, dents, dings, scrapes, and other apparently minor damage, while sometimes appearing insignificant, modify the load path through the structure creating importance of review maintenance undesirable stress concentrations. Before evaluating or repairing any damage to stressed aircraft structure, the airframe manufacturers structural repair manual should be consulted for the correct evaluation criteria and instructions concerning the use of the correct tools, methods, and equipment. removing practices…” scratches NTSB (1989) FAA (1990) 18
  99. 99. Cracking from Gouge Example - Alert SB on 747 to address skin cracks from gouges between a doubler and a lap splice Edge of modification doubler Edge of lap splice Clad Gouge Crack locationDoubler Skin Crack Skin
  100. 100. Maintenance Damage at Fillet SealRepair doublerremoved fromthis areaScratch marks invicinity of fillet seal
  101. 101. Cracking at Scribe MarkExternal viewExternal view Internal view Internal view
  102. 102. Corrosion Removal and Repair• Ensure complete removal of corrosion prior to refinishing • Trapped corrosion will continue to propagate• Replace any damaged/removed finishes • Unfinished area will susceptible to continued corrosion• Restore all drain paths 22
  103. 103. Lap Splice Repair withUnremoved Corrosion
  104. 104. Pressure Deck Repairwith Unremoved Corrosion
  105. 105. Drain Paths• Ensure repairs do not obstruct drain paths • A drain path may be a gap in a structural assembly• Check leveling compound condition • Replace as necessary and check adjacent areas• Check for adequate drainage by spraying area with water • Restore drain paths as necessary 25
  106. 106. Summary• Small damage can cause cracks and require frequent inspections • Crack patterns resulting from damage can vary from cracking addressed in maintenance programs• Completely remove all damage (scratches, gouges, corrosion) prior to repair• Maintenance activity must not create damage• Regulatory authorities have heightened awareness of incomplete damage removal 26
  107. 107. Charging forEngineering Services 0
  108. 108. Objective• To clarify Service Engineering policy of charging for: • Structural Repair Approval • Engineering Technical Support that Boeing considers to exceed normal fleet support 1
  109. 109. Contents• Structural Repair Approval• Work Exceeding Normal Fleet Support 2
  110. 110. Structural Repair ApprovalApplies to: • Operators who are not operating any airplane purchased new from Boeing and who are not the first lessee of a new airplane received directly from Boeing • Maintenance, Repair and Overhaul (MRO) facilities working on components that they own, or working on an airplane or component belonging to operators as defined above 0Includes operators working as an MRO 3
  111. 111. Chargeable Structural RepairsInclude requests that require Boeing to: • Conduct structural analysis to substantiate the structural integrity of a repair 0With or without a request for FAA 8110-3 form approval • Accomplish a Damage Tolerance Analysis (DTA) to provide inspection intervals and / or methods 4
  112. 112. Structural Repair - CommunicationAll Operator Messages • M-1001-00-0021, Dated 21 Dec 2000 0 Implements new charge policy • M-7200-01-02479, Dated 18 Oct 2001 0 Clarifies charge policy • M-7200-02-00355, Dated 1 Mar 2002 0 Expedite by providing PO number with request 5
  113. 113. Structural Repair – Charge Criteria• Single charge of $3500 covers both the repair and 8110-3 • 8110-3 requested at time of repair request• Single charge of $3500 covers both the repair and DTA • DTA requested at time of repair request• New charge of $3500 for an 8110-3 or DTA • 8110-3 or DTA requested after a chargeable repair response has been provided 6
  114. 114. Expediting Repair Approval Response• MRO / Operator has good credit with Boeing • Provide PO number or promise date with initial request 0 Specify company providing PO 0 Include Spares Customer Code• MRO / Operator does not have good credit with Boeing • Provide payment with initial request 0 Specify company providing payment 0 Include Spares Customer Code 7
  115. 115. Work Exceeding Normal Fleet Support• Applies to all customers• Assistance provided with a contract• Policy has always been in effect• All Operator Message issued for clarification • M-7200-02-01766, Dated 11 Nov 2002 8
  116. 116. Examples of Work Requiring Contract• Issuance of multiple FAA 8110-3 forms on previously approved repairs• On-site technical assistance• Structural repairs requiring substantial engineering man-hours• Third party work support• Support to modify airplane configuration 9
  117. 117. Contract Process Flow• Customer sends in request for assistance• Boeing determines work exceeds normal fleet support• Boeing advises customer that assistance requires a contractual agreement• If customer concurs, Boeing provides a Draft Contract for review and signature• Engineering proceeds to accomplish work when customer has signed Contract 10
  118. 118. SummaryStructural Repair Approval• Requests for structural repair assistance are subject to $3500 charge, even if no 8110-3 form is requested• Applies to: • Operators who are not operating any airplane purchased new from Boeing and who are not the first lessee of a new airplane received directly from Boeing • MROs working on their own components or the above operators’ airplanes or components 11
  119. 119. SummaryWork Beyond Normal Fleet Support• Engineering Technical Assistance will be provided under a contractual agreement for time, labor and material• Applies to all customers 12
  120. 120. Structural Health Management (SHM) 1
  121. 121. ObjectivesReduce cost of ownership and introduceon-condition structural maintenanceDevise an automated structural inspectionsystem capable of diagnostics, predictingstructural damage and specifying maintenanceactions 2
  122. 122. Contents• SHM Goals and Benefits• SHM Definition, Development and Technology Status• Industry Collaboration/Engagement• Shm Road Map 3
  123. 123. Potential SHM Benefits• Reduced operating cost• First step in progression to on-condition structural maintenance• Longer economical airframe utilization• Structural inspection tasks customized for each airplane• Could be adapted to current fleet• Allowance of a third option in SBs: Monitoring• Determine the extent of accidental damage in areas prone to accidental damage• Open architecture Allowance to expand upon existing system after airplane entry to service 4
  124. 124. What is SHM?• SHM is a structural condition assessment system using sensor technology that has potential to locate airplane structural damage • Environmental • Accidental• Load monitoring capabilities are under consideration 5
  125. 125. IVHMAHM SHM IVHM (Integrated Vehicle Health Management) Structures (SHM) • Corrosion detection (ED)Systems (AHM) • Environmental, delamination• Fault message integration and Accidental Damage• Data processing for system monitoring reliability information • Load monitoring • Inspector’s aid
  126. 126. IVHM Operating ConceptMaintenanceControl In Flight Portable Tool Engineering &In Maintenance Technical Maintenance Documentation Technician 7
  127. 127. Potential Onboard Health Management Hierarchy Air/Ground Wireless Ground Maintenance Data Flight crew Communication Link Access Terminal Storage displays Airplane Health Manager Flight Crew/Dispatch AlertingCabin Core Avionics CCS Health Propulsion/ Flight ControlsHealth Mgr Health Mgr Mgr Utilities Structures Health Mgr Health Mgr Health Mgr Structures HM Sensors
  128. 128. SHM Technology Testing• Laboratory testing• In-service testing 9
  129. 129. SensorsMoisture Sensor Damage Sensors 10
  130. 130. Accidental Damage Sensors Installed Surface mounted layers• Two embedded layers• Three part surface mounted layers bonded to inner mold line Embedded layers 11
  131. 131. Event and Damage DetectionSkin-Stringer Composite Barrel Demonstration 12
  132. 132. Data Logger boxesinstalled on equipment racks Battery
  133. 133. Sensor installed next to stringer 8 20 Flight data 12/23/03 3:00pm to 12/24/03 4:51pm Effective CrRt ReHum (NO UNITS) 7 Temperature 31 Temperature 10 6 Corrosion 0Corrosion Rate (microns/year) 5 Rate 4 Humidity -10 3 -20 2 -30 1 0 -4012/23/03 2:01 PM 12/23/03 6:49 PM 12/23/03 11:37 PM Time/Date 12/24/03 4:25 AM 12/24/03 9:13 AM 12/24/03 2:01 PM Time
  134. 134. Implementation• What will it take to implement SHM? • Correlation between SHM technology and existing maintenance 0Can SHM satisfy current fleet structural inspection requirements? • Qualification and approval of SHM as part of airplane maintenance (existing and new fleets) • Industry working together 0In non-competitive areas 0Regulatory concerns 15
  135. 135. Implementation Timeline 2008 2003Phase I• Technology Development and testingPhase II• Working together meetings with industry and regulatory agencies• Introduce concept for current fleetPhase III• Expand testing and confirm in-service a/c SHM architecture• Regulatory and industry concurrence/acceptancePhase IV• Implementation on 7E7
  136. 136. Summary• SHM has potential to reduce airplane structural maintenance cost• Testing and development of SHM technology in progress• Work with airplane operators and regulators to gain acceptance in the industry• Technology Demonstration and Poster Session 17
  137. 137. 737 Lap Joints 0
  138. 138. Contents• Background• Service Bulletin (SB) 737-53A1255• SB 737-53A1177, Revision 7 changes• Inspection issue• Fleet Experience• Rulemaking 1
  139. 139. Background• Two service bulletins currently address cracking in lap joints on 737s: • SB 737-53A1177, Revision 6 0 MSD cracking common to lower row of lower skin 0 Eccentric load path, high bending stresses 0 Modification of S-4, S-10, S-14 lap joints between BS360 and BS908 at 50,000 f/c 0 Inspect other laps beginning at 70,000 f/c, repeat inspections at 5,000 f/c • SB 737-53A1255 0 One-time inspection program instituted in October 2002 for unmodified airplanes over 45,000 f/c 2
  140. 140. Background L/P 292-2565 Lap Joint Configuration Covered by SB 737- 53A1177 and SB 737- 53A1255Cracks inlower skin Acommonto lap jointlower row Cracks initiate at faying surface A A-A 3
  141. 141. Background SB 737-53A1177, Rev 6 Repair Locations STA STA STA STA STA STA 259.50 360 540 727 908 1016 S-26RBL 0 S-19R S-25RS-24R S-20RS-19R S-14RS-14R S-10RS-10R S-4RS-4RS-4L S-4LS-10LS-14L S-10LS-19L S-14LS-24L S-20L S-19L S-25LBL 0 S-26L Areas to be Repaired (50,000 f/c threshold) 4
  142. 142. BackgroundSB 737-53A1177, Rev 6 Inspection Locations STA STA STA STA STA STA 259.50 360 540 727 908 1016 S-26RBL 0 S-19R S-25RS-24R S-20RS-19R S-14RS-14R S-10RS-10R S-4RS-4RS-4L S-4LS-10LS-14L S-10LS-19L S-14LS-24L S-20L S-19L S-25LBL 0 S-26L Repetitive Inspections (Initial = 70,000 f/c Repeat = 5,000 f/c) 5
  143. 143. SB 737-53A1255• Two recent fleet findings have increased concern with extent of lower row cracking • 23-inch linked crack at S-4L on a 737–200 (60,300 f/c) 0Extensive unlinked cracks 0Damage exceeded all prior in-service findings • Significant cracking at S-4R on a 737–300 (52,400 f/c) 0BS 639 to BS 650: every fastener hole had cracks over 0.5 inches emanating from each side 0BS636 to BS620: extensive cracking 0Three stinger clips cracked (one completely severed) 6
  144. 144. Crack Locations STA STA STA STA STA STA 259.50 360 540 727 908 1016 S-26RBL 0 S-25R S-19R S-20RS-24RS-19R S-14RS-14R S-10RS-10R 639 650 23-inch crack S-4RS-4RS-4L on 737-200 11 inches of un-linked S-4LS-10LS-14L 616 639 cracks on 737-300 S-10L S-14LS-19L S-20LS-24L S-19L S-25LBL 0 S-26L Areas reported with large cracks Smaller cracks found 7
  145. 145. Over Wing Cracking
  146. 146. Close up of DamageSeveredStringer Clip Cracks
  147. 147. SB 737-53A1255• Alert SB released 17 Oct 2002• FAA reviewing for possible rulemaking• Inspection directed at unmodified airplanes and does not apply to airplanes under 45,000 f/c • Airplanes inspected prior to AD require no further inspections• Accomplishment instructions included note about sensitivity of NDT inspections • Specific human factor issues listed that could lead to missed cracks • NDT technicians should be specifically trained and qualified with LFEC and MFEC procedures 10
  148. 148. Inspection Details• One-time inspection program with tiered approach based on cycles and extent of findings • Over 50,000 f/c, inspect within 45 days • Between 45,000 - 50,000 f/c, inspect within 90 days • Internal MFEC and visual inspections at S-4 between BS540 and BS727 0If significant cracking found in over wing area, LFEC inspect all other SB 737-53A1177 affected lap joints 0If significant cracking is found with LFEC inspection, internal MFEC inspection required • Directed at specific lap joint where significant damage was found 11
  149. 149. Over Wing Inspection LocationsInspect S-4L and S-4R Lap StringerJoint and Stringer Clips ClipBetween BS 540 and BS 727 Typical Crack S-4 Tear Strap Typical Cracks 12
  150. 150. Fleet Inspection Results• Records indicate 35 airplanes have been inspected • 20 over 50,000 f/c • 15 between 45,000 and 50,000 f/c • Most have had little or no findings • 5 needed SB lap joint repair• Data is currently being reviewed • No consistent crack distribution found • Cutout sections being inspected to determine crack lengths • Evaluation for frequency and location of cracking 13
  151. 151. Proposed Revision 7 Changes• Compliance related to SB 737-53A1255 inspection results• Additional repair information for 737–200C’s at S-4R and S-10R between BS360 and BS540• Revisions to 737–300 repair drawings• New repair drawings for 737–400/–500s• Additional window corner inspections and updates to window corner repairs• Release anticipated late 2003 14
  152. 152. Proposed Revision 7 Changes• Compliance changes may result from data gathered from SB 737-53A1255 inspections • Data is being reviewed 0Inspection thresholds may be impacted and one-time internal inspection likely to be added 0Modification threshold may be reduced below current 50,000 f/c 15
  153. 153. Proposed Changes: 737-200C• Rev 6 has incomplete repair information for S-4R and S-10R between BS360 and BS540 • Instructs operators to contact Boeing for instructions • Boeing has provided repair information and approval as AMOC to AD • Rev 7 will add complete repair instructions• To date, 18 cargo airplanes have been modified 16
  154. 154. Proposed Changes: 737-300/400/500• 737 –300 repair drawings are incomplete • Unique structure not covered on drawings 0S - 4L/R just aft of BS540 0S - 10L/R just forward of BS540 0S - 10L/R between BS500D and BS520 0Boeing has provided data to operators and approval as AMOC to AD • Add window corner repairs to S-10 and S-14 drawings• Repair drawings and accomplishment instructions for 737- 400/500s will be added 17
  155. 155. Current Window Belt Recommendations• Accomplish inspections of 3 fasteners in corners common to window frame at 50,000 f/c • BS360 to BS540, Upper Forward / Lower Aft corners • BS727 to BS908, Lower Forward / Upper Aft corners • If no cracks, accomplish Preventative Modification 0Install oversize fasteners at all three locations • Accomplish repair if cracks detected 0Integrated with lap joint repair• Cracks believed to be common to skin/bonded doubler only 18
  156. 156. Rev 6 Window Corner Inspections Rev 6 Inspection Locations 19
  157. 157. Rev 6 Window Corner Experience• Cracks reported deviating from Rev 6 instructions • Common to skin/bonded doubler along S-11 and S-13 and along window frame • In S-11 and S-13 sections • In window frames• Boeing has confirmed cracks• Revised recommendations necessary to capture new crack findings in fleet 20
  158. 158. Rev 7 Window Corner Inspections Rev 6 Inspection Locations New Rev 7 Inspection Locations 21
  159. 159. Proposed Window Corner Changes• Additional inspections and/or rework may be necessary for airplanes inspected per Rev 6 • Rev 7 will include a flowchart to guide operators in decision making• New repair figures will be added to SB, SRM, and 737–300/400/500 repair drawings• Option to replace window belt skin assembly to eliminate need to inspect/repair window corners under study 22
  160. 160. Proposed Window Corner Changes• Data package will be provided to operators in mid 2003, in advance of Rev 7 • Revised inspection instructions, including use of 0.020 notch for open hole inspections 0Updated repair instructions 0Expanded allowable damage limits 0Format similar to Rev 6 • Will be FAA approved and considered an AMOC to AD 2002-07-08, paragraph (g) and (n) 23
  161. 161. Inspection Issue• Alodine (conversion) coated rivets replaced anodized coated rivets 0Phased into production 1985-1995• Alodine coated rivets render sliding probe and Magneto Optical Imaging (MOI) NDT methods ineffective• Significantly impacts lower row external inspections in SB 737-53A1177 and SB 737-53A1255 • May result in missed crack indications 24
  162. 162. Anodize vs. Alodine RivetsConsistently long Inconsistent short rivetrivet signals signals with a phase change Good EDM notch signal Unacceptable EDM notch signal 3/16 inch Anodize Rivets 3/16 inch Alodine Rivets 25
  163. 163. Inspection Issue• Method to identify type of coating on installed rivets under study • Existing sliding probe inspection method may be used on anodized coated rivet locations • Alternative inspection method to be developed for alodine coated rivets• Working with affected operators to identify airplanes impacted near-term by SB 737-53A1177 inspections • Additional inspection steps may necessary 26
  164. 164. Fleet Experience• Approximately 155 airplanes modified to date • 134 737-200/-200Cs • 21 737-300s 0140 have accomplished lap joint cutout repair 015 have Rev 1, 2 or 3 Preventive Modification• No common crack distribution • Significant cracks found on some airplanes • Others have been relatively crack free• Window corner cracking will impact downtime• On-site engineering and NDT assistance available 27
  165. 165. Rulemaking• Three ADs issued against Rev 6 effective 17 May 2002 • AD 2002-07-08: Lap joint cutout repair at 50,000 f/c, window corner inspections at 50,000 f/c, and lower lobe inspections at 70,000 f/c • AD 2002-07-10: Replacement of obsolete local SRM lap joint repairs • AD 2002-07-11: SRM repair of local areas aft of wing on airplanes L/P 1-291• Immediate Adopted Rule expected for SB 737-53A1255 to provide one-time inspection recommendations 28
  166. 166. Summary• Two recent fleet findings have increased concern with extent of lower row cracking • One-time SB 737-53A1255 inspection program• Revision 7 currently scheduled for release late 2003 • Major changes have been communicated to operators • Compliance changes may result from SB 737- 53A1255 inspections • Window corner data package available 2nd Qtr 03• Three ADs for SB 737-53A1177, Rev 6• FAA will review SB 737-53A1255 inspections for possible rulemaking 29
  167. 167. 2003 Structures ConferenceService Engineering Nondestructive Testing (NDT) Personnel Training and Certification 1
  168. 168. ObjectivesIncrease awareness of Nondestructive Testing(NDT) training and certification options, that canpromote better inspections with fewer false ormissed indications. 2
  169. 169. Contents• Background• Options for Training and Certification• FAA Guidelines• CAA/European Requirements 3
  170. 170. Background• Increasing reliance on NDT detecting smaller cracks • Improper inspection evaluation has caused additional downtime and cost • Cracks may be missed due in part to inadequate training• Regulatory authorities now expecting implementation of training and/or certification programs 4
  171. 171. Incorrect Evaluation Result Assumed crack 4 inch 5
  172. 172. Example of Missed Cracks 6
  173. 173. Options• Select a training and / or certification program • Central certification - external agency • Local training - internal airline / MRO• Use an NDT service provider with trained and certified personnel using the same programs 7
  174. 174. Central Certification Programs• USA • ASNT Level III Certification• Europe • EN 473 equivalent for each country• Canada • CAN/CGSB-48.9712-95 Canadian General Standards Board version of ISO 9712 8
  175. 175. Internal Airline/MRO Training and Certification Programs• USA standards • AIA-NAS 410 Draft to combine with EN 4179 (NAS/EN XXXX) • ASNT SNT-TC-1A Guidelines • ATA 105 Guidelines for Training & Qualifying Personnel in NDT• European standards • EN 4179 equivalent for each country 9
  176. 176. FAA Advisory Circular Pending• Requires documented education, training and experience• Recognizes standards / specifications (i.e., EN/PCN/ASNT/CGSB)• Recognizes organizations with independent examination• Recognizes three levels of competence 10
  177. 177. European Standards• EN standards• Internal and external specifications • Three levels of competence • Documented education, training and experience• Regulatory action • Example: U.K. CAA Airworthiness Notice No. 94 regulates training and certification of NDT personnel 11
  178. 178. Summary• Controlled NDT training and certification reduces false and missed indications• Meet a recognized standard that may include: • Recording past training and experience • Attending training for NDT methods • Level II and III examinations as needed • Establishing a company Written Practice 12
  179. 179. 737 ClassicFuselage Issues 0
  180. 180. ObjectiveProvide overview of 737 Classic fuselagestructural issues that may be subject offuture FAA rulemaking. 1
  181. 181. Contents• Existing Service Bulletin Recommendations• New In-Service Findings• New or Revised Boeing Recommendations• FAA Action 2
  182. 182. 737 Classic Fuselage Issues SB 737-53-1216Frame Cracks Between S-8 and S-9SB 737-53A1224 Lap Joint SB 737-53A1228 Lower Cracking: 1-291 Cargo Door Cutout Corner CracksSB 737-53A1210and 737-53A1234 Skin Cracks atChem-mill steps SB 737-53-1125 Frame Cracks Above S-14SB 737-52A1149 SB 737-53A1166Fwd Cargo Door S-18A Cracking at BS727#4 Beam Cracks SB 737-53A1254 Over-wing Exit Frame Cracks 3
  183. 183. Cracked Frames Above S-14 SB 737-53-1125 Frame Cracks Above S-14 4
  184. 184. Cracked Frames Above S-14Existing Recommendations• SB 737-53-1125, Rev 2 released Nov 1991 • Addresses fatigue cracking common to frame between S-13 and S-14 0Last fastener common to fail-safe chord at frame splice 0Effective L/P 1-1919 • Preventive modification by 40,000 f/c 0Trim last fastener off of fail-safe chord 0Install oversize rivets at remaining 4 locations 0Repair frame per SRM if cracked 5
  185. 185. Cracked Frames Above S-14In-Service Findings• Severed BS 747 frame and a 1.3 inch crack in adjacent BS 767 frame at same location • Cracks initiated below existing SB737-53-1125 inspection threshold of 40,000 f/c • Frames between BS380 and BS908 similarly designed• Cracks considered a safety of flight issue • Multi-element damage (adjacent frames cracked) • Frames cracked near S-14 lap joint which has a demonstrated multiple-site damage issue (SB737-53A1177) 6
  186. 186. Cracked Frames Above S-14 Frame Cracks Start At End Fastener Common to Splice 7
  187. 187. Cracked Frames Above S-14• New Recommendations • SB 737-53-1125 to be revised and upgraded to Alert status 0Initial inspection threshold and interval changed 0Inspection method changed 0Repair for cracks provided • Rev 2 preventive mod should not be accomplished• FAA Action • Reviewing SB 737-53-1125 Rev 3 for possible rulemaking 8
  188. 188. Frame Cracks Between S-8 and S-9 SB 737-53-1216 Frame Cracks Between S-8 and S-9 9
  189. 189. Frame Cracks Between S-8 and S-9• Existing Recommendations • No Service Bulletin• In-Service Findings • Numerous cracked frames between S-8 and S-9 common to air conditioning attach brackets 0Reports from 9 airplanes 0Cracks typically 1 inch or less in length • Cracks considered a safety of flight issue 0Multi-element damage (adjacent frames cracked) 0Near S-10 lap joint which has a demonstrated multiple-site damage issue (SB 737-53A1177) 10
  190. 190. Frame Cracks Between S-8 and S-9 11
  191. 191. Frame Cracking between S-8 and S-9• New Recommendations • New 737-53-1216 SB to be released mid 2003 0Effective L/P 991-3132 0Applies to all frames between BS380 and BS908 similarly designed 0Will provide inspection thresholds, terminating modification and repairs• FAA Action • Will review for possible rulemaking following release of SB 737-53-1216 12
  192. 192. Skin Cracks at Chem-mill StepsSB 737-53A1210 and 737-53A1234 Skin Cracks at Chem-mill Steps 13
  193. 193. Skin Cracks at Chem-mill Steps• Existing Recommendations • SB 737-53A1210, Rev 1 released Oct 2001 0Addresses cracking along edges of chem-mill pockets • Cracks found at S-12, above S-4, S-10 and S-14 lap joints, and below S-14 on numerous airplanes 0Effective L/P 292-2565 0Crown area • NDT and visual inspections at 35,000 f/c or within 4,500 f/c from release of Rev 1 • Repeat visual inspections at 4,500 f/c • Repair per SB if cracks found 14
  194. 194. Skin Cracks at Chem-mill Steps• Existing Recommendations • SB 737-53A1210, Rev 1 released Oct 2001 0Section 41 and areas below S-14 • Visual inspections at 40,000 f/c or within 4,500 f/c from release of Rev 1 • Repeat at 9,000 f/c intervals • Repair per SRM or contact Boeing if cracks found 15
  195. 195. Skin Cracks at Chem-mill Steps• Existing Recommendations • SB 737-53A1234 released June 2002 0 Testing predicts cracking along edges of chem -mill pockets in above S-4 and S-10 lap joints • No in-service cracks reported 0 Effective L/P 2553-3132 0 Accomplish external NDT and visual inspections at 21,000, 33,000 or 42,000 f/c depending upon location and series • Initial threshold dependent upon model and location • Repeat visual @ 1,200 f/c or NDT @ 3,000 f/c • Repair per SB if cracks found 16
  196. 196. Skin Cracks at Chem-mill Steps Crack at Chem-mill Step A A A-A 17
  197. 197. Skin Cracks at Chem-mill Steps• In-Service Findings: SB 737-53A1210 • Numerous cracks along edge of chem-milled pockets 0Initiating well below 35,000 f/c inspection threshold 0Appearing in other areas not currently covered in SB 0Multiple cracks in adjacent bays • Cracking considered a safety of flight issue 0Multi-element damage (adjacent bays cracked) 0Near lap joints which have a demonstrated multiple-site damage issue (SB 737-53A1177) 18
  198. 198. Skin Cracks at Chem-mill Steps• Recommendations • SB 737-53A1210 to be revised 0Reduce thresholds for initial visual and NDT inspections and repeat visual inspections 0Expand inspection areas due to in-service findings 0Develop new NDT internal inspection technique for unmodified areas covered by external repairs• FAA Action • Reviewing SB 737-53A1210 and 737-53A1234 for possible rulemaking 19
  199. 199. Forward Cargo Door Beam CracksSB 737-52A1149Fwd Cargo Door#4 Beam Cracks 20
  200. 200. Forward Cargo Door Beam Cracks• Existing Recommendations • SB737-52A1100, Rev 4 released Mar 2001 0Addresses cracking on forward cargo door in lower frames and #5 (lower) cross-beam 0Cracks in radius of frames and in web of #5 cross-beam 0Effective for all 737 Classic airplanes 0Mandated by AD 2000-07-06 • For both frame and #5 cross-beam 0Visual inspections 0Repair per SB if cracks found 0Accomplish preventive mod if no cracks found 21
  201. 201. Forward Cargo Door # 4 Beam Cracks #4 Cross Beam Typical Crack A A #5 Cross Beam 22
  202. 202. Forward Cargo Door # 4 Beam Cracks• In-Service Findings • Four operators reported cracking in #4 stop beam 0Root cause of cracks attributed improper door rigging and/or a cracked #5 cross beam 0Additional load being redistributed into #4 cross beam 23
  203. 203. Forward Cargo Door Beam Cracks• New Recommendations • Release SB737-52-1149 in late 2003 0Will provide inspection, repair, and modification details for #4 cross beam 0Similar to SB737-52A1100 0Effective for all 737 Classic airplanes (L/P 1-3132)• FAA Action 0Reviewing SB737-52-1149 for possible rulemaking 24
  204. 204. Lap Joint Corrosion and Cracking SB 737-53A1224Lap Joint Lower Cracking: 1-291 25
  205. 205. Lap Joint Corrosion and Cracking• Existing Recommendations • AD 2000-17-04 mandated original inspection program • SB 737-53A1224, Rev 1 released Mar 2002 0 Addresses cracking and corrosion in cold-bonded lap joints 0 Effective L/P 1-291 0 NDT external and internal crack inspections repeated • 1,000 f/c intervals for airplanes above 70,000 f/c • 2,000 f/c intervals for airplanes below 70,000 f/c • Repair cracks or corrosion per SRM 0 Visual corrosion inspections repeated every 4 years 0 Modification of all 44 lap joints terminates inspections 26
  206. 206. Lap Joint Corrosion and Cracking Upper skinCracks in lowerfastener rowCovered bySB 737-53A1224 Corrosion - upper and lower skin Lower skin Cracks in upper fasteners row 27

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