Boeing asks airlines to inspect MD-80 fleets

LOS ANGELES (AP) -- The builder of MD-80 jetliners urged airlines Wednesday to inspect their fleets after a damaged piece of the tail<br>wing that could have contributed to the crash of Alaska Airlines

Wednesday, February 9th 2000, 12:00 am

By: News On 6

LOS ANGELES (AP) -- The builder of MD-80 jetliners urged airlines Wednesday to inspect their fleets after a damaged piece of the tail
wing that could have contributed to the crash of Alaska Airlines Flight 261 was recovered.

The Boeing Co. recommended that mechanics visually check the jackscrew that moves the horizontal stabilizer, a tail-mounted wing that is the focus of the investigation into the Jan. 31 crash that killed 88 people off the coast of Southern California.

The recommendation covers about 2,000 planes, in the MD-80 series like the Alaska Airlines plane, as well as MD-90s, DC-9s and
Boeing 717s.

Carriers should check the jackscrew assemblies at their convenience, Boeing said. Boeing bought aircraft builder McDonnell
Douglas in 1997.

Inspection reports will be studied by the Federal Aviation Administration, which can order further action if it finds evidence of a safety problem.

We've been talking to the carriers and strongly encouraging them to make this inspection as rapidly as possible," said FAA spokesman Eliot Brenner.

Alaska, American and Delta airlines said earlier in the day they had begun inspecting their fleets. Some schedule delays were
possible, airline officials said.

Alaska expected to have its 34-plane fleet inspected within hours, American said it would take a week to look at its 284 series
planes and Delta said all 136 of its series planes would be inspected by the end of the week.

Pilots aboard the ill-fated flight spent their final minutes struggling to control the stabilizer before the aircraft nose-dived into the Pacific.

A two-foot section of the jackscrew was recovered with the main wreckage of the MD-83 about 10 miles off the coast. At first Alaska
said Wednesday the jackscrew was found to be stripped, but later the airline changed its statement and said only that the screw had
been damaged, reflecting the description by the National Transportation Safety Board.

"It appeared to investigators who looked at the mechanism ...that there was some damage to it," NTSB Chairman James Hall said. "It was unclear whether the damage was pre-impact or from hitting the water."

More than 1,100 MD-80 series aircraft are flown by nearly 70 airlines worldwide, making them some of the most popular commercial
jetliners ever built.

The Federal Aviation Administration has not told airlines to make additional checks of the tail section of MD-80 series aircraft, but that could change as the investigation evolves,
agency spokesman Paul Turk said. "We won't hesitate to do whatever is necessary," he said.

Investigators in the Alaska Airlines crash are focusing on the stabilizer, a wing-like device on the jet's tail, because pilots reported problems with it after taking off from Puerto Vallarta, Mexico, for San Francisco.

The jackscrew is powered by two motors and resembles the corkscrew-like device that opens many automatic garage doors. If the jackscrew was damaged during flight, the horizontal stabilizer could move beyond its normal range, causing the tail wing to stall,
or lose its lift, said William Waldock, associate director for the Center for Aerospace Safety Education at Embry-Riddle Aeronautical
University in Prescott, Ariz.

It would be nearly impossible to recover from such a stall, Waldock said.

The pilots would not be able to control the up-or-down motion of the aircraft -- which would be consistent with flight data that shows the plane went into a 3.4-mile nosedive and radar tracking that shows something may have fallen off the plane as the dive began.

The plane's autopilot was disengaged when the jetliner reached 29,000 feet, and the jet was flown manually for one hour and 53
minutes. Pilots say it is unusual to fly manually for that long and could suggest a problem with the autopilot or any number of other systems.

Officials said the MD-83 involved in the crash had two maintenance write-ups last fall for problems with the horizontal stabilizer. In October, the system was checked and the plane returned to service. A month later, mechanics replaced a switch.