November 2002 NTSB Hearings on American Airlines 587 Crash Focus Now on the Pilots, Not the Composite Fin - Part 2 of 2

摘要

Our attendee at the NTSB review of the crash of American Airlines flight AA587 in November 2001 in New York told us of his personal conjecture on the meaning of the information presented at the meeting: It is not clear from the evidence presented whether the failure load as described accounted for the actual environment of the AA587 fin. These conditions were significantly less severe than the full hot-wet condition used in the structural testing. The temperature at JFK was 42 F versus the 158 F "hot" condition tested. The moisture content of specimens retrieved form the failed AA587 fin was measured by Airbus at 0.6 percent, whereas the design "wet" moisture content that the preconditioned structural test fin reached 0.9 percent. Another area of interest to the composite community involves the use of NDI to inspect the tail structure. NDI is performed at the factory for final inspection. Standard maintenance inspection of the fin defined by Airbus and certified by the DGAC and FAA is a thorough visual inspection every five years. Immediately after the AA587 accident, the FAA issued an Emergency Airworthiness Directive (AD) for all A300-600R operators to perform a "one-time detailed visual inspection" of the vertical tails. According to the FAA, "The purpose of this AD was to quickly determine whether there was any systematic degradation of the structure to an extent that would pose a safety threat and whether a repair noted in the structure of the accident aircraft was common of other aircraft." No damage was found in the fleet, but there were many calls for more rigorous inspection. In April the FAA rejected a petition by about 200 American Airlines pilots who fly the A300-600R that NDI (ultrasonic inspection) be performed, stating the tail was "designed and certified with an appropriate, intended inspection method".