Alaska Airlines parent company disclosed last week that federal prosecutors have reactivated a criminal investigation of maintenance performed on an MD-83 that crashed off the coast of California three years ago because of inadequate lubrication.
In a March 12 filing with the U.S. Securities and Exchange Commission, Alaska Air Group said the U.S. Attorney for the Northern District of California resumed the investigation after the National Transportation Safety Board concluded in December that the plane crashed because a screw and nut in its horizontal stabilizer had been inadequately greased.
The Seattle, Washington-based carrier declined further comment, as did the U.S. attorneys office.
Alaska Airs Oakland, Calif., maintenance facility was already under investigation when Flight 261 plunged into the sea Jan. 31, 2000, killing 88 passengers and crew members. Prosecutors had begun a grand jury investigation in 1998 after a former lead mechanic accused the shop of falsifying maintenance records that year. The shop maintains Alaska Airs MD-80/90 series planes. After the crash, prosecutors extended their case to include Flight 261.
Their investigation was halted in December 2001. The U.S. attorneys office said it had completed the investigation into the 1998 maintenance activities, deciding they did not warrant criminal charges. The portion of the investigation concerning the crash was suspended with the possibility that it could be reopened after the safety board finished its inquiry.
The NTSB finished its work in December, concluding that the horizontal stabilizer – a tail wing assembly that controls the planes pitch – had failed due to excessive wear of threads on a nut that helps limit the stabilizers up and down movement. The board blamed Alaska Air for not adequately greasing the system and the Federal Aviation Administration for allowing the company to lengthen its maintenance intervals.
At the urging of Alaska Air, the safety board looked at whether two greases used by the carrier were incompatible or otherwise caused the excessive wear on the nut. After extensive tests, the board concluded that the greases were not incompatible and did not contribute to the crash.
Representatives of all 88 passengers and crew members initially sued Alaska Air, but the company subsequently settled 48 of those cases. The rest have been consolidated and are scheduled for trial in civil court in July.