Alaska Airlines Flight 261

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January 31, 2000, Alaska Airlines Flight 261 Details On January 31, 2000, Alaska Airlines, Inc., flight 261, a McDonnell Douglas MD-80, crashed into the Pacific Ocean about 2.7 miles north of Anacapa Island, California. The two pilots, three cabin crewmembers, and 83 passengers on board were killed, and the impact destroyed the airplane. Flight 261 was operating as a scheduled international passenger flight from Lic Gustavo Diaz Ordaz International Airport (PVR), Puerto Vallarta, Mexico, to Seattle-Tacoma International Airport, Seattle, Washington, with an intermediate stop planned at San Francisco International Airport, San Francisco, California.
National Transportation Safety Board Ruling
The National Transportation Safety Board determined …show more content…

(See figures 3 through 6 for details of the longitudinal trim system actuating mechanism and the jackscrew assembly.) The upper end of the jackscrew assembly is attached to the front spar of the horizontal stabilizer, and the lower end is threaded through the acme nut, which is connected to the vertical stabilizer with a gimbal ring and retaining pins. The acme screw and nut each have two threads that rotate in a spiral along their length. Figure 6 shows the longitudinal trim system and the jackscrew …show more content…

Investigators observed that, when the dial indicator was mounted above the acme nut instead of below it (as is called for in the current end play check procedure), the dial indicator was easier to install, its face could be seen more easily (without the need for an inspection mirror, as was the case when it was installed below the acme nut), and the end play measurement could be more easily discerned from the movement of the indicator needle. Investigators also observed that, when the dial indicator was mounted such that the plunger contacted the canted surface of the acme nut stop lug at a skewed angle to the plunger axis, the end play measurement was lower than it was when it contacted a level surface on the acme nut at a right angle to the plunger axis. On April 13 and November 20, 2000, Boeing issued revisions to the end play check

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