Loss of Control and Impact with Pacific Ocean Alaska Airlines Flight 261
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NTSB/AAR-02/01 PB2002-910402 Aircraft Accident Report Loss of Control and Impact with Pacific Ocean Alaska Airlines Flight 261 McDonnell Douglas MD-83, N963AS About 2.7 Miles North of Anacapa Island, California January 31, 2000 RANS T PO National L R A T N LURIB US A P UNUM E O T I Transportation I O T N A N Safety Board S A D F E R T Y B OA Washington, D.C. Aircraft Accident Report Loss of Control and Impact with Pacific Ocean Alaska Airlines Flight 261 McDonnell Douglas MD-83, N963AS About 2.7 Miles North of Anacapa Island, California January 31, 2000 RAN S P T O L R A T LUR IBUS N P UNUM A E O T I I O T A N N S A F D E AR NTSB/AAR-02/01 T Y B O PB2002-910402 National Transportation Safety Board Notation 7263E 490 L’Enfant Plaza, S.W. Adopted December 30, 2002 Washington, D.C. 20594 National Transportation Safety Board. 2003. Loss of Control and Impact with Pacific Ocean, Alaska Airlines Flight 261, McDonnell Douglas MD-83, N963AS, About 2.7 Miles North of Anacapa Island, California, January 31, 2000. Aircraft Accident Report NTSB/AAR-02/01. Washington, DC. Abstract: This report explains the accident involving Alaska Airlines flight 261, a McDonnell Douglas MD-83, which crashed into the Pacific Ocean about 2.7 miles north of Anacapa Island, California. Safety issues discussed in this report include lubrication and inspection of the jackscrew assembly, extension of lubrication and end play check intervals, jackscrew assembly overhaul procedures, the design and certification of the MD-80 horizontal stabilizer trim control system, Alaska Airlines’ maintenance program, and Federal Aviation Administration (FAA) oversight of Alaska Airlines. Safety recommendations are addressed to the FAA. The National Transportation Safety Board is an independent Federal agency dedicated to promoting aviation, railroad, highway, marine, pipeline, and hazardous materials safety. Established in 1967, the agency is mandated by Congress through the Independent Safety Board Act of 1974 to investigate transportation accidents, determine the probable causes of the accidents, issue safety recommendations, study transportation safety issues, and evaluate the safety effectiveness of government agencies involved in transportation. The Safety Board makes public its actions and decisions through accident reports, safety studies, special investigation reports, safety recommendations, and statistical reviews. Recent publications are available in their entirety on the Web at <http://www.ntsb.gov>. Other information about available publications also may be obtained from the Web site or by contacting: National Transportation Safety Board Public Inquiries Section, RE-51 490 L’Enfant Plaza, S.W. Washington, D.C. 20594 (800) 877-6799 or (202) 314-6551 Safety Board publications may be purchased, by individual copy or by subscription, from the National Technical Information Service. To purchase this publication, order report number PB2002-910402 from: National Technical Information Service 5285 Port Royal Road Springfield, Virginia 22161 (800) 553-6847 or (703) 605-6000 The Independent Safety Board Act, as codified at 49 U.S.C. Section 1154(b), precludes the admission into evidence or use of Board reports related to an incident or accident in a civil action for damages resulting from a matter mentioned in the report. iii Aircraft Accident Report Contents Abbreviations . ix Executive Summary . xii 1. Factual Information . 1 1.1 History of Flight . 1 1.2 Injuries to Persons. 10 1.3 Damage to Airplane . 10 1.4 Other Damage. 10 1.5 Personnel Information. 10 1.5.1 The Captain . 10 1.5.2 The First Officer. 11 1.6 Airplane Information . 11 1.6.1 MD-80 Longitudinal Trim Control System Information . 13 1.6.1.1 Primary Trim Control System . 18 1.6.1.2 Alternate Trim Control System . 18 1.6.1.3 Autopilot Pitch Control . 19 1.6.2 Design and Certification of MD-80 Series Airplanes . 19 1.6.2.1 General. 19 1.6.2.2 Longitudinal Trim Control System Certification. 19 1.6.3 Maintenance Information. 24 1.6.3.1 Alaska Airlines’ MD-80 Maintenance Program . 24 1.6.3.1.1 Maintenance Program Development Guidance. 24 1.6.3.1.2 Alaska Airlines’ Continuous Airworthiness Maintenance Program . 26 1.6.3.1.3 Alaska Airlines’ Reliability Analysis Program. 26 1.6.3.2 Jackscrew Assembly Lubrication Procedures . 29 1.6.3.2.1 Jackscrew Assembly Lubrication Intervals. 31 1.6.3.2.1.1 Manufacturer-Recommended Lubrication Intervals. 31 1.6.3.2.1.2 Alaska Airlines’ Lubrication Intervals . 32 1.6.3.2.2 Chronology of Grease Type Changes . 34 1.6.3.2.3 July 19, 2002, Alaska Airlines Maintenance Information Letter . 36 1.6.3.3 Procedures for Monitoring Acme Nut Thread Wear . 37 1.6.3.3.1 Defining and Calculating Wear Rate. 37 1.6.3.3.2 Development of End Play Check Procedures . 38 1.6.3.3.2.1 Alaska Airlines’ End Play Check Procedure . 43 1.6.3.3.3 Horizontal Stabilizer Restraining Fixture . 44 1.6.3.3.3.1 General . 44 1.6.3.3.3.2 Alaska Airlines-Manufactured Restraining Fixtures . 44 1.6.3.3.4 End Play Check Intervals . 47 1.6.3.3.4.1 Manufacturer-Recommended End Play Check Intervals . 47 1.6.3.3.4.2 Alaska Airlines’ End Play Check Intervals . 47 1.6.3.4 Accident Airplane’s Maintenance Information . 49 1.6.3.4.1 Accident Airplane’s Last C Check Requiring an End Play Check . 50 Contents iv Aircraft Accident Report 1.6.3.4.2 Maintenance Personnel Statements Regarding the Accident Airplane’s Last End Play Check . 53 1.7 Meteorological Information . 54 1.8 Aids to Navigation . 54 1.9 Communications . 54 1.10 Airport Information . 55 1.11 Flight Recorders. 55 1.11.1 Cockpit Voice Recorder. 55 1.11.1.1 CVR Sound Spectrum Study . 55 1.11.2 Flight Data Recorder . 56 1.12 Wreckage and Impact Information . 57 1.12.1 General . 57 1.12.2 Horizontal Stabilizer Jackscrew Assembly Components. 58 1.13 Medical and Pathological Information . 62 1.14 Fire. 62 1.15 Survival Aspects . 62 1.16 Tests and Research. 63 1.16.1 Airplane Performance . 63 1.16.1.1 Airplane Performance Simulation Studies. 66 1.16.2 Metallurgical Examinations . 67 1.16.2.1 Horizontal Stabilizer Forward Spar . 67 1.16.2.2 Acme Screw. 68 1.16.2.3 Acme Screw Torque Tube . 70 1.16.2.4 Lower Mechanical Stop and Corresponding Spline Area on the Acme Screw . 71 1.16.2.5 Acme Nut. 72 1.16.2.6 Acme Nut Thread Remnant Examination . 76 1.16.3 Shear Load Capability of the Acme Nut Threads . 77 1.16.4 Studies of Thread Stress and Deformation . 77 1.16.5 Torque Tube Testing . 79 1.16.6 Additional Safety Board Jackscrew Assembly Examinations . 80 1.16.6.1 February 2000 Post-AD 2000-03-51 Jackscrew Assembly Examinations . 80 1.16.6.2 Examinations of Hawaiian Airlines’ Jackscrew Assemblies. 81 1.16.6.3 Examinations of Alaska Airlines Reports of Acme Screw “Wobble”. 83 1.16.7 Chemical and Microscopic Analyses of Grease Residues from the Accident Jackscrew Assembly . ..