WASHINGTON - Investigators focused Thursday on the role that grease and maintenance may have played in a breakdown in the tail section of the Alaska Airlines passenger jet that plunged into the Pacific Ocean in January.
The tail jackscrew was found thread-worn and fractured when recovered by divers on Feb. 8. It helps control up-and-down movement in the McDonnell Douglas MD-83 aircraft.
While investigators have concluded that the jackscrew stripped through a nut and broke, leaving the pilots unable to control the horizontal stabilizer, they said it will be months before they can determine why.
In the second day of a hearing to collect evidence and testimony this week, the National Transportation Safety Board heard from three witnesses about possible causes of the Jan. 31 crash that killed all 88 people aboard.
Under scrutiny are the Seattle-based airline's maintenance problems, which have been the subject of a criminal investigation, and whether the Boeing Co.-approved grease may have corroded the jackscrew's threads.
The jet was made by McDonnell Douglas. Boeing took over McDonnell Douglas in a 1997 merger.
Alaska Airlines' former engineering director Jay Maloney acknowledged that a maintenance record displayed at the hearing was incomplete, lacking proper signatures.
''I'm trying to understand how it (the paperwork) was advanced further,'' said board member Frank McGill. ''How do we know they changed the lubrications?''
''I don't have an explanation for how it got to that point,'' Maloney replied.
Two Federal Aviation Administration officials, questioned for most of the day, were not eager to be pinned down on crash theories.
''We don't deal on the level of anything more than 'What if?''' testified Lee R. Koegel, an FAA aviation safety inspector from Long Beach, Calif.
His colleague, Mike O'Neil, a Long Beach-based FAA aerospace engineer, testified the jackscrew was found with little grease on it, and other considerations such as ''fatigue'' limits and maintenance history were not critical factors.
''The jackscrew assembly ... had exhibited an acceptable service record,'' he said.
O'Neil dodged a question whether the horizontal stabilizer system that includes the jackscrew is safe for the Boeing MD-80 twinjets or their DC-9 predecessors. He said it ''demonstrates compliance'' with federal safety regulations.
An hour later, board member John Clark circled back. ''Since we've had this catastrophic problem,'' he asked, ''would that suggest to you that there's a problem with the regulations?''
''No, sir,'' replied O'Neil.
O'Neil said FAA inspectors such as himself concern themselves with ensuring aircraft meet government requirements for safety and ''to a lesser degree about wear'' of aircraft parts.
Louie Key, regional director of the airline's mechanics' union, disputed some of O'Neil's testimony. He told The Associated Press that when he witnessed the jackscrew's recovery from the water, ''it was apparent there was grease on the jackscrew'' with a ''very thin sheen or film'' over the entire assembly.
On the Net: National Transportation Safety Board site: http://www.alaskasworld.com/newsroom/ASnews/ASstories/AS-20001214-10 2004.asp http://www.ntsb.gov