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Screw blamed for Alaska Airlines crash

Investigators believe the gimbal nut, left, failed and came off the jackscrew, right.
Investigators believe the gimbal nut, left, failed and came off the jackscrew, right.

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WASHINGTON (CNN) -- Insufficient lubrication of a critical control mechanism caused an Alaska Airlines jet to plunge into the ocean off Los Angeles almost three years ago, killing all 88 people on board, investigators have determined.

Alaska Airlines Flight 261 was en route from Puerto Vallarta, Mexico, to Seattle, Washington, by way of San Francisco, California, when it crashed into the Pacific Ocean on January 31, 2000.

Investigators focused on the jackscrew assembly in the horizontal stabilizer, which keeps the plane flying level.

A source close to the investigation said the National Transportation Safety Board's draft report on the crash will conclude that a lack of lubrication of the jackscrew caused excessive wear and caused the gimbal nut -- which moves the two-foot jackscrew up and down to adjust to stabilizer -- to fail.

The report is expected to focus on potential contributing factors, including a lack of Federal Aviation Administration oversight of Alaska Airlines maintenance operations and faulty design of the jackscrew assembly, which left no backup system when the jackscrew's threads failed, the source said.

The FAA allowed the airline to extend its maintenance schedule of the jackscrew assembly, sources said.

Since the crash, the FAA has required more frequent lubrication of those assemblies, agency spokesman Paul Takemoto said.

Before the crash, it required all carriers to lubricate jackscrews after each 2,135 hours of flight time. After after the crash, they tightened that requirement to every 650 hours.

The NTSB is scheduled to review the conclusions and release a final report on the matter Tuesday.

All 83 passengers and five crew members were killed when the MD-80 crashed north of Los Angeles.

Before the crash, the doomed jet's pilots told air traffic controllers they had a jammed stabilizer and were struggling to maintain altitude.

FAA spokesman Diane Spitalari said the agency has dramatically increased the number of inspectors it now has working with the airline from nine to 37.

Alaska Airlines representatives said the air carrier has undergone a stringent review process, including a major FAA inspection and Defense Department audits, since the accident.

The Transportation Department's inspector general testified in April that investigators found problems to "some degree in the internal maintenance monitoring systems at all nine air carriers reviewed, and in at least three cases these problems were significant."

"Both our report and FAA, in its own review, showed that FAA inspectors needed to provide better surveillance of air carrier's internal maintenance oversight systems," the report said.

CNN Aviation Correspondent Patty Davis and Producer Beth Lewandowski contributed to this report.



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