The National Transportation Safety Board today released the following updated information on its investigation of the November 12, 2001, crash of American Airlines flight 587, an Airbus A300-600, in Belle Harbor, New York, which resulted in the deaths of all 260 persons aboard and 5 persons on the ground.
Vertical Stabilizer and Rudder
Testing has begun on small composite samples that have been removed from the accident aircraft's vertical stabilizer and rudder - which separated from the aircraft during the accident - at NASA's facility in Hampton, Virginia. Three of the six lugs (the attachment points between the stabilizer and the empennage) will be taken to the U.S. Army's Research Laboratory at Aberdeen Proving Ground in Maryland to undergo a CT-Scan (commonly referred to as a CAT-Scan) to further define any sub-surface damage. Two other lugs are being taken to the Lawrence Livermore National Laboratory in California because they are too large to be accommodated at Aberdeen. The Board has not made a decision yet on whether to take the sixth lug for further testing.
Previous Airbus Events
The vertical stabilizer of an American Airlines Airbus A300-600 that experienced an upset event in 1997 (see February 25 advisory for details) was removed from the aircraft and has undergone ultrasonic examination at American Airlines' maintenance facility in Tulsa, Oklahoma. This aircraft experienced high lateral loads associated with reversing rudder movements during the 1997 accident and Safety Board, Airbus, American Airlines and BEA (the NTSB counterpart agency in France) investigators wanted to see if any damage might have resulted from that event that wasn't detected in the post-accident inspection. This event was classified as an accident because a flight attendant received a serious injury.
Investigators report that an indication of damage (possibly delamination) has been found that apparently was not present at the time of manufacture. The indication is at the pin bushing of the right rear lug. Airbus has informed the Board that the stabilizer will be removed from service. The Safety Board will conduct further examinations of this component once the current testing in Tulsa is complete.
Airbus and the FAA are evaluating service history data to identify other upset or maneuver events, if any, that may warrant further investigation. Airbus has advised the NTSB that in May 1995, a FedEx Airbus experienced large rudder deflections, but not rudder reversals. The deflections were the result of a rudder trim/autopilot interaction. A course of action will be taken once the evaluation is complete (This is not to be confused with the FedEx Airbus A300-600 that was found during maintenance in February to have a damaged rudder [mentioned in NTSB Chairman Marion Blakey's February 8 press conference statement]. That rudder is being taken to Germany for further examination).
"Filtering" of Flight Recorder Data
As previously reported, some of the information dealing with flight control movements contained on flight 587's flight data recorder was filtered (see January 15 media advisory for details). The Board has made good progress in defining the original filter characteristics, and in designing an inverse filter to better define actual rudder movement. The Board still has some on-aircraft testing to complete to finalize its work in that area. Airplane motion and loads will be further refined through simulation and analysis.