The National Transportation Safety Board today released the following update 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.
Composite Lug Test
On August 13, 2003, the NTSB conducted a lug sub- component structural test at the Airbus test facility in Hamburg, Germany. Engineers from the NTSB, Airbus, American Airlines, BEA, and the NASA Langley Research Center supported the testing and analysis.
The test component was a rear main attachment lug from an A310-300 Carbon Fiber Reinforced Plastics (CFRP) fin box skin panel. The panel was originally constructed as a manufacturing quality test article and was used to demonstrate the interior quality of the skin panel.
The test was to demonstrate the behavior of the lug under a load condition similar to that experienced by American Airlines 587 during the accident flight. The load condition used was derived from the flight data recorder information and the subsequent structural finite element analyses.
During the test, the lug structurally failed at a load beyond its design ultimate limit. The test failure appeared to be consistent with calculated failure load analyses performed by both Airbus and NASA Langley. Work is continuing at the Safety Board to continue refining a reliable estimate of the loads on the AA587 fin during the accident.
The Safety Board has obtained two other lugs for testing. Two rear lugs were removed from the tail fin from the A-300-600 aircraft that was involved in a loss-of- control incident in 1997 as American Airlines flight 903 (see Fifth Update, February 25, 2002). These lugs will undergo structural tests in December of this year and February 2004 in Hamburg.
The team has completed its examination of the flight control cable routing for possible failure modes that could have led to the accident. The team has also examined the design of the A300-600 rudder limiter system and performed comparisons of other rudder-limited systems.
The group has examined issues related to the directional stability and control characteristics of the Airbus A300-600, obtaining expert information on pilot/aircraft coupling design issues, evaluating aircraft response to differing rudder designs, and examining the service history of the A300-600 for high tail load events that might involve issues related to the accident.
The Safety Board currently expects to deliberate over a final accident report in a public meeting in Washington, D.C. during the Spring of 2004.