NTSB: 757 In Overrun Missing A Bushing
Investigators poring over the American Airlines Boeing 757-200 that ran off Runway 19 while landing at Jackson Hole, Nov. 19, have so far found that a bushing was missing on part of the auto speed brake mechanism. During testing, investigators found "no discrepancies" in the aircraft's air/ground, autobrake, and thrust reverser systems. They found the linear actuator of the auto speed brake mechanism had been "improperly installed." The actuator resides in the cockpit pedestal and without the bushing, a cam and switch could become misaligned. The NTSB is investigating system operation with consideration to that condition. The CVR data has been transcribed and will be released when the NTSB's public docket is opened. The NTSB's FDR group has begun the process of mining data and has released some information.
Flight 2253's data recorder showed that the speed brakes were manually extended by the flight crew during the approach and left in the armed position until landing. The FDR does not record the position of individual spoiler panels. As the aircraft touched down, the aircraft's air/ground system registered that the aircraft was on the ground but switched for roughly one half second to air before registering ground for the remaining of the rollout. During that half second the speed brake handle momentarily moved "toward the down position" and then returned to armed. The thrust reversers began to deploy during that half second and remained in the "in-transit" position for about 10 seconds. They then moved to stowed and back again to in-transit, this time for six seconds, before becoming deployed. The FDR indicates it took 18 seconds from the time the reversers began moving until they were fully deployed. The NTSB says it has examined video taken by a passenger during landing. Video shot by a passenger during landing -- against the airlines regulations -- is available here.