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Aging Transport Systems Rulemaking Advisory Committee Harmonization Working Group 10 Small Transport Category Aircraft Final Report and Recommendations February 7, 2003 1 BACKGROUND ..............................................................................................................5 EXECUTIVE SUMMARY.................................................................................................6 PURPOSE .......................................................................................................................7 ESTABLISHING A HARMONIZATION WORKING GROUP (HWG) ..............................8 PART I - NON-INTRUSIVE INSPECTIONS ....................................................................9 Airplane Evaluation Document Development .............................................................9 Sample Fleet ................................................................................................................10 Survey Accomplishment Observations .....................................................................11 Survey Results Evaluation Method ............................................................................11 Evaluation Results Summary .....................................................................................12 Evaluation Results Summary Matrix..........................................................................13 Non-intrusive Survey Conclusions ............................................................................14 Non-Intrusive Evaluation Recommendations ...........................................................14 PART II - SERVICE DATA REVIEW .............................................................................15 Review Methods ..........................................................................................................15 Service Data Review Results Summary.....................................................................16 Service Data Review Notes.........................................................................................16 Service Data Review Recommendations...................................................................17 PART III – REPETITIVE INSPECTION AIRWORTHINESS DIRECTIVE REVIEW.......17 Task Statement ............................................................................................................17 Review methods ..........................................................................................................17 Repetitive Action AD Review Conclusions ...............................................................18 Repetitive Action AD Review Recommendations .....................................................18 2 PART IV – INTRUSIVE EVALUATIONS.......................................................................19 Introduction..................................................................................................................19 Test Procedure ............................................................................................................19 Samples........................................................................................................................19 Summary of Findings:.................................................................................................20 Recommendations: .....................................................................................................21 PART V ATSRAC WORKING GROUPS 6 TO 9 - RECOMMENDATIONS RELEVANT TO SMALL TRANSPORT CATEGORY AIRCRAFT.....................................................22 Methodology ................................................................................................................22 Sub-Groups..................................................................................................................22 Harmonization Working Group 6 Work Product Review:.........................................22 Background................................................................................................................22 Summary of HWG-6 Tasking: ....................................................................................23 HWG-6 Tasking Products: .........................................................................................23 HWG-10 Conclusion, Recommendations and Rationale............................................23 Harmonization Working Group 7 Work Product Review ..........................................24 Background................................................................................................................24 Summary of HWG-7 Tasking: ....................................................................................24 HWG-7 Tasking Products: .........................................................................................25 HWG-10 Conclusion, Recommendations and Rationale............................................25 Harmonization Working Group 8 Work Product Review ..........................................26 Background................................................................................................................26 Summary of HWG-8 Tasking: ....................................................................................26 HWG-8 Tasking Products: .........................................................................................26 HWG-10 Conclusion, Recommendations and Rationale............................................26 Harmonization Working Group 9 Work Product Review ..........................................27 Background................................................................................................................27 Summary of HWG-9 Tasking: ....................................................................................27 HWG-9 Tasking Products: .........................................................................................27 3 HWG-10 Conclusion, Recommendations and Rationale............................................28 CONCLUSION AND SUMMARY OF RECOMMENDATIONS FOR SMALL TRANSPORT CATEGORY AIRCRAFT........................................................................29 ADDITIONAL RECOMMENDATIONS FROM HWG-10................................................31 CLOSING REMARKS ...................................................................................................32 APPENDIX 1 - ATSRAC HWG-10 MEMBERS AND PARTICIPANTS.........................33 APPENDIX 2 - AGING SMALL TRANSPORT WIRING EVALUATION PROTOCOL ..35 APPENDIX 3 - SUPPLEMENTAL LABORATORY WIRING TESTS FOR SMALL TRANSPORT AIRPLANES...........................................................................................45 APPENDIX 4 – INTRUSIVE INSPECTION REPORT....................................................54 APPENDIX 5 – REVISION TO HWG8 APPENDIX A....................................................55 4 Background Safety concerns about aging wiring systems in airplanes were brought to the forefront of public and governmental attention by a fatal accident involving a Boeing Model 747-131 airplane on July 17, 1996. The National Transportation Safety Board (NTSB) determined that “the probable cause of the accident was an explosion of the center wing fuel tank resulting from ignition of the flammable fuel/air mixture in the tank.” Although they were unable to determine the specific source of the ignition, the NTSB found several potentially unsafe conditions in and near the electrical wiring of the airplane, including cracked wire insulation, metal shavings adhered to a floor beam along which fuel quantity indication system wires were routed, other debris, and sulfide deposits. The NTSB also found that deterioration, damage, contamination of aircraft wiring and related components, and unsatisfactory repairs were common in the airline transport airplanes that it inspected during the investigation. According to the NTSB’s report “the condition of the wiring system in the accident airplane was not atypical for an airplane of its age and one that had been maintained in accordance with prevailing industry practices.” The NTSB found the deteriorated conditions of aircraft wiring systems of particular concern because the existence of these conditions revealed the general shortcomings of the current maintenance practices. As a result of its examinations the NTSB stated that a large portion of the aircraft wiring is difficult, if not impossible, to inspect because of its inaccessibility and that wire damage or other potentially unsafe conditions may not be detected, even on visible and accessible portions of aircraft wiring. The NTSB concluded “insufficient attention has been paid to the condition of aircraft electrical wiring, resulting in potential safety hazards.” The accident investigation into the July 17, 1996, fatal accident resulted in a heightened awareness of the importance of maintaining the integrity of aircraft wiring. The FAA began to investigate fuel tank wiring, and to strengthen its focus on aging wiring in general. In 1997, the White House Commission on Aviation Safety and Security (WHCSS) issued the following recommendation to the FAA: “In cooperation with airlines and manufacturers, the FAA’s Aging Aircraft Program should be expanded to cover non-structural systems.” ATSRAC was formed shortly after this mandate. Phase 1 of this program included performing a non-intrusive and intrusive inspection of aircraft wiring. The data collected during these inspections was used to develop recommendations for regulatory agencies and industry to review and make comment. Phase 1 was conducted from 1998 to 2001 through Harmonization Working Groups (HWG) 1 to 5. The recommendations from HWG 1 through 5 lead to the development of a Phase 2 tasking. HWG 6 to 9 were developed to review the data and make the next level of recommendations to ATSRAC and the FAA. The basis of all effort was for Transport Category Aircraft with =30 passengers and/or =7500 pound payloads. As a result of the Bombardier Aerospace Learjet 35 accident on October 25, 1999, the NTSB recommended to FAA that all Transport Category Aircraft be included in the 5 Study even though NTSB found no electrical wiring safety related issues in the accident aircraft. In October 2001, Small Transport Working Group (STWG) was formed to assist FAA/JAA in the study. In January 2002, STWG was added to ATSRAC as Small Transport Aircraft Harmonization Working Group 10 (STAHWG10). In April 2002, the Federal Register announced and established STAHWG10 tasking them to: 1. Investigate the applicability of previous ATSRAC recommendations to small transport airplane electrical wire systems; and 2. Identify issues unique to these (aircraft), systems and recommend appropriate actions based on results from— • Performing a sample inspection of in-service and retired small transport airplanes that correlate to the inspection previously performed under the original task 1 and task 2 of the ATSRAC; • Reviewing fleet-service history to identify trends or areas for actions; and • Coordinating with other ATSRAC Harmonization Working Groups to ensure that the ATSRAC reports to the FAA/JAA consider the needs of small transport airplanes. (i.e. review/modify collateral documents the working group determines to be appropriate and submit them to the ATSRAC for review and approval by January 2003.) 3. Make recommendations to ATSRAC and the FAA/JAA. HWG-10 began its tasks in earnest starting in April of 2002 to investigate the applicability of previous ATSRAC recommendations to Small Transport Category Aircraft (6 to 30 type certificated passenger load and