Alaska Air Maintenance Questions Intensify

Questions about Alaska Airlines’ maintenance procedures intensified Friday as federal officials announced that no lubrication grease was found on a key part recovered from the wreckage of the Alaska jet that crashed six weeks ago.

The airline’s maintenance has been the subject of two federal investigations into allegations that mechanics at its Oakland maintenance facility falsified inspection records and allowed at least two “unairworthy” planes to fly.

The MD-83 that crashed Jan. 31 had been serviced repeatedly in Oakland, but National Transportation Safety Board investigators have said it is much to early to say whether maintenance was a factor in the crash.

Several minutes before Flight 261 plunged into the sea near Anacapa Island, killing all 88 people on board, the pilots radioed that they were having trouble controlling the jetliner because of problems with its horizontal stabilizer.

The NTSB investigation has focused for weeks on the stabilizer--the wing-like portion of the tail that largely controls the up-or-down pitch of the plane’s nose.

The stabilizer is moved by a jackscrew, a thick, threaded bolt that travels back and forth through a threaded gimbal nut.

“The thread on the accident gimbal nut is missing, and remnant strips of the thread were wrapped around the jackscrew,” NTSB Chairman Jim Hall said Friday. “No grease was found on the portion of the jackscrew where the gimbal nut would normally be expected to operate.”

Hall said it has not yet been determined whether the threads were damaged before the crash or stripped by the plane’s high-speed impact with the sea.

However, several safety experts have suggested that the pilots’ problems with the stabilizer, which may have begun shortly after the plane took off from Puerta Vallarta more than two hours before the crash, might have been caused by damage that occurred over a protracted period.

The NTSB said inspections ordered by the Federal Aviation Administration after the crash have turned up damaged jackscrew mechanisms on eight similar planes, one of which was being flown by Alaska.

“The eight other assemblies have been removed because of excessive end play or the presence of metal shavings,” Hall said. “We also received, for comparative purposes, five additional Alaska Airlines gimbal nuts that had been rejected because of excessive wear during overhauls conducted prior to the accident.”

Hall said NTSB investigators will conduct additional interviews with Alaska maintenance personnel in Oakland.

Under an FAA-approved plan, Alaska was permitted to inspect the stabilizer actuator assemblies as infrequently as every 2,500 flight hours, or about every eight months.

Since the crash, the FAA has ordered that the assemblies be checked every 650 flight hours.

Hall said the investigation on the ocean floor off Port Hueneme was completed Thursday. About 90% of the wreckage has been recovered, about a third more than originally expected.

“All of the major components of the tail section are among the recovered pieces,” Hall said. “A portion of the fairing just above the horizontal stabilizer has not been located.”

Radar data show that a piece may have broken off just before the plane began its final dive. But investigative sources say that if it was the fairing, it probably broke off as a result of stabilizer failure, and did not cause the failure. An undersea search where the piece apparently landed, about four miles from the main debris field, failed to turn up anything.

The Ventura County coroner’s office said the fragmented remains of 58 of the victims have been positively identified. DNA testing is continuing in an attempt to identify more.