National Transportation Safety Board
Office of Public Affairs
National Transportation Safety Board Chairman Jim Hall today issued the following statement on the investigation of the crash of Alaska Airlines flight 261:
The Safety Board's investigation of the January 31 crash of Alaska Airlines flight 261 is continuing, both here in Washington and in California.
As has been widely reported, based on an examination of the jackscrew/gimbal nut assembly from the horizontal stabilizer of flight 261, which was recovered by the United States Navy from the wreckage field on the bottom of the Pacific Ocean, the Federal Aviation Administration ordered an inspection of those assemblies for more than 1,000 aircraft in the U.S. commercial airline fleet (the FAA can provide a full account of the extent and results of those inspections). Some assemblies that were found with "anomalies" were removed from the aircraft. As of today, our materials laboratory in Washington has received 5 of those assemblies, in addition to the one from the accident aircraft. More are expected to arrive.
Safety Board materials specialists are examining the units to determine the extent of wear or damage to them. They also are examining grease samples from each unit to identify specific products being used, to determine compatibility between those products and to detect possible contamination. This work is expected to go on for several weeks.
The threads of the gimbal nut from the accident aircraft are stripped, and metal shreds made of the same material as that nut were found on the jackscrew. There are also impact marks on the outside of the gimbal nut and the lower stop nut; the Board will try to determine if those impact marks - as well as the stripping of both nuts' threads - were made before the aircraft contacted the water or after. The primary and alternate trim motors were recovered, but because of damage during the impact and subsequent immersion in sea water they were not able to be operationally tested. However, laboratory examination of these components is still planned.
A Safety Board representative visited Trig Aerospace in Santa Ana, California, the current supplier of the jackscrew assemblies for MD-80 series aircraft. We obtained records associated with the accident jackscrew.
The assembly on the accident aircraft was supplied to McDonnell Douglas by the Peacock company of Norwalk, California on June 28, 1990. In late 1994, Peacock was purchased by the Derlan company, which in turn was purchased by Trig in July 1999. All of the parts of the jackscrew assembly were manufactured in the United States.
Interviews were conducted with the maintenance personnel in Oakland, California, who performed the last scheduled inspection of the unit on the accident aircraft in September 1997. They told the Board they were unable to recollect many details about the inspection process. The Board continues to examine the history of the accident jackscrew assembly from the date of its manufacture.
Taped conversations between the accident flight crew and airline maintenance personnel during the last half hour of the flight are being analyzed. It appears that the pilots made contact with maintenance personnel about the stabilizer problem around the time that the cockpit voice recorder tape begins.
A sound spectrum analysis is being conducted on the cockpit voice recorder to determine the source of as many noises as possible. The aircraft's previous flight was examined on the flight data recorder; no unusual movements were noted for the stabilizer.
The United States Navy has completed mapping the wreckage area and as a result I have directed the Navy to accelerate the salvage operation next week. Remotely operated vehicles have been used to identify parts of the aircraft we want to recover. Because the water is too deep (about 700 feet) for divers, mechanical equipment will bring the pieces up. Among sections of the aircraft to be recovered will be the remaining parts of the tail section up to the aft pressure bulkhead, flight controls attached to the wings, and the cockpit area. The pieces will be placed into a hangar at the Port Hueneme, California Naval Base for examination and documentation.
As of this morning, the Ventura County Medical Examiner's Office reported that the remains of 49 of the 88 persons aboard the aircraft had been identified and family notifications are proceeding.
We are now entering a stage of the investigation where the tasks are more long-term. We do not expect to issue another factual update for several weeks.
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NTSB Office of Public Affairs: (202) 314-6100
The National Transportation Safety Board (NTSB) is an independent federal agency charged with determining the probable cause
of transportation accidents, promoting transportation safety, and assisting victims of transportation accidents and their families.