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part two of Four |
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'Aft cargo door was latched - but the upper half of the door was torn off from the lower half.' The Spectre of Faulty Wiring Causing Non-Plug Cargo Door Openings may be with us again on the 747 |
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| K.F. Chou Accident Investigation Division Aviation Safety Council 16th Floor, 99 Fu-Hsing North Road, Taipei 105, Taiwan, R.O.C. Ken Smart Chief Inspector of Accidents, Air Accidents Investigations Branch AAIB DRA Farnborough Hants GU14 6TD United Kingdom W.T. (Bill) Tucker Director General, Investigation Operations Transportation Safety Board Canada Lyle Streeter FAA AAI Aircraft Accident Investigator FAA National Headquarters 800 Independence Avenue, S.W Building FOB 10A, Room 838, Washington D.C 20591 James F. Wildey II National Resource Specialist National Transportation Safety Board 490 L'Enfant Plaza East, SW. Washington, DC 20594 Dear Mr. Chou, Mr. Smart, Mr. Tucker, Mr. Wildey, and Mr. Streeter, 1 August 2002 'Aft cargo door was latched but upper half of the door were tore off from the lower half.' I got chills when I just read the above quote from the ASC press release. The description is that of the forward cargo doors of Air India Flight 182, Pan Am Flight 103, United Airlines Flight 811, and Trans World Airlines Flight 800. Pictures and text of all on website at www.corazon.com and available in pdf for download. (Door story). The cargo door suddenly fractures longitudinally at the aft midspan latches that have no locking sectors. The bottom eight latches with strengthened locking sectors are able to stop the inadvertent unlatching. The bottom locking sectors were strengthened after the PA 125 event but too late for United Airlines Flight 811. From NTSB AAR 92/02: '1.16.1.2 After Recovery of the Door The documentation of the recovered cargo door was divided into four areas: 1) door structure, 2) master latch lock system, 3) latch system, and 4) hook system. A description of the recovered door follows. 1. Door Structure: The cargo door had fractured longitudinally near the mid-span lap joint near stringer 34R, just beneath the mid-span torque tubes.' The description does not mean that the shorted wiring/cargo door rupture/explosive decompression/inflight breakup explanation happened to China Airlines Flight 611. It does mean that extensive examination and consideration of the wiring/cargo door explanation be conducted for China Airlines Flight 611. That level of examination was conducted for United Airlines Flight 811 and is seen in NTSB AAR 92/02 and available on the www.corazon.com web site. It now appears hull rupture occurred aft of wing in section 46 for China Airlines Flight 611. The logical suspects are still there, aft pressure bulkhead, all the doors, and also the repair. Each gives specific evidence if it occurred if one knows where to look. The aft cargo door needs the hinges checked for overtravel, the pins for high pressure 'bluing', the fuselage skin for paint transfer from door, status of manual locking handle, status of pressure relief doors, torque tubes for bending, bellcranks for slack, status of ten latches and eight locking sectors, all wiring that activates door unlatch motor checked for chafing, cracking, or arcing. The unhappiness for the investigators is the prospect of the aft cargo door rupturing in flight for electrical problems because that will show inherent faults in all Poly X wired Boeing 747s which exploit the design weakness of outward opening non plug cargo doors that have only one midspan latch for eight feet of fuselage slice and those lone midspan latches do not have safety locking sectors. From ASC for China Airlines Flight 611: 'The sound prior to the CVR power cut-off was more likely be the rapid decompression rather than the explosive decompression or external explosive, after the spectrum analysis by the NTSB, ASC, and Boeing personnel at the NTSB Lab.' The later implications for all is that Air India Flight 182 and Pan Am Flight 103 were not bombs and Trans World Airlines Flight 800 was not a CWT fire/explosion with undetermined ignition source. The explosions and noises reported for all were explosive decompressions yes, but not from bombs. To use logic for China Airlines Flight 611, a bulk cargo door has never split in flight or on the ground. The passenger doors aft have never opened in flight or on the ground. The aft pressure bulkhead has never fractured on the ground but has in flight. The aft cargo door has never opened in flight but has on the ground and has leaked often. What is the most likely suspect? I would say the aft pressure bulkhead but apparently that is not named as a suspect so that leaves the aft cargo door. The aft cargo door and the forward cargo door are identical in size, function, and weaknesses. Cheers, Barry John Barry Smith barry@corazon.com
Aviation Safety Council Press Release Subject: CI611 Accident investigation update Date: 2002.7.30 Dr. Kay Yong, Managing Director of ASC held a press conference today and released the following information. Radar Data After trip to Mainland China, the Flight Data Recorder group had confirmed that there were 3 additional transponder radar points received from Xiamens's secondary radar after the CVR power cut off. Time Altitude 15:28:05 34,613 15:28:09 34,777 15:28:13 34,843 CVR sound spectrum analysis A simulation flight was conducted on June 29 to compare the un-identified sound from CVR and the initial inspection is as follow. 15:38:34-15:20:30 4 times unidentified Ka-Da sounds could be the knobs by the flight crew. 15:21:52-15:21:13 No spectrum comparison to the 7 times unidentified heart beat sounds. The sound prior to the CVR power cut-off was more likely be the rapid decompression rather than the explosive decompression or external explosive, after the spectrum analysis by the NTSB, ASC, and Boeing personnel at the NTSB Lab. The 0.3 second blank might come from the defect of the CVR tape.
Wreckage There were a total of 828 wreckage pieces been recovered including; 4 engines, nose gear, three set of main landing gear, tail, both wings, cockpit, section 41 through 44, and part of section 46, approximately 60% of the total wreckage There were 4 wreckage pieces that required further examination Uncontinuous flat fracture found on the piece near bulk cargo door Spiked-tooth shaped damage on the lower portion of the door 4L, which might be the result of high-energy impact. Flat fractures from door 5L and a steel metal piece. Aft cargo door was latched but upper half of the door were tore off from the lower half. Wreckage inspection Samples from those 4 pieces had sent to Chung Shan Institute of Science and Technology(CSIST). Representatives from ASC, NTSB, Boeing and CAL will commence detail inspection and further testing on July 31. There are three sets of 11 samples will send to CSIST, NTSB Lab and Boeing. The ASC noted that all those wreckage pieces would be inspected according to the process; however, whether those pieces were the causes of the in-flight break up still remain unknown and need further studies.
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