Rapport du NTSB publié hier 20 juin:
A 2015 engine fire on a British Airways 777-236ER was caused by a fatigue crack in the high-pressure compressor stage 8 disk web and subsequent uncontained engine failure, which led to the detachment of the main fuel supply line, the National Transportation Safety Board found Wednesday.
The high-pressure compressor stage 8-10 spool in the left engine, one of two GE GE90-85BG11 engines on the airplane, had accumulated 11,459 total cycles. Investigators found that the crack initiated after about 6,000 cycles, much earlier than the engine’s manufacturer, GE, predicted; the cause of the crack initiation could not be identified. There were no additional cracks found on the disk during a post-accident inspection of the engine.
The disk web was not an area that either the Federal Aviation Administration or the manufacturer required to be inspected, so the crack went undetected. During maintenance in September 2008, when the high-pressure compressor was removed from the engine and disassembled, exposing the stage 8-10 spool, the surface crack length would have been about 0.05 inches. “If the disk web had been required to be inspected during this maintenance, the crack should have been detectable,” the report said. The lack of inspection procedures for the stage 8 disk contributed to the accident, the NTSB found. After the accident, GE implemented inspection procedures designed to detect disk web cracks.
Le moteur a été coupé 43 secondes après l'ordre de coupure (bien vu eolien au message 3 en page 1): mauvaise application de la procédure, l'absence de coupure n' a été remarquée que par le 3 ème pilote.
Le rapport complet est disponible ici:
L'ensemble des "dockets" disponibles ici: