Washington -- Computer Alert Problem & Possible Connection to Alaska Airlines

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Interesting crosspost from Spider's discussion group at http://hv.greenspun.com/bboard/q-and-a-fetch-msg.tcl?msg_id=004FjG

The last 12/17/2001 entry is particularly interesting.

Computer Warning 3 Days After Alaska Airlines Crash greenspun.com : LUSENET : Y2K discussion group : One Thread --------------------------------------------------------------------------------

Washington -- An Alaska Airlines computer alerted the carrier to check the jackscrews of its MD-80 planes for problems three days after Flight 261 slammed into the Pacific Ocean, killing all 88 people aboard, an airline official testified today. SF Gate

-- spider (spider0@usa.net), December 16, 2000

Answers 3 other worn jackscrews found before jet crash WASHINGTON -- Alaska Airlines replaced worn jackscrews in three of its planes only months before the crash of Flight 261. Three days after Alaska Flight 261 plunged into the Pacific, an automated computer program alerted the airline to potential wear problems with the part that failed and caused the crash, an airline official testified yesterday.

The three jackscrews were replaced within a five-month span in 1999. This was the first time since Alaska began operating the McDonnell Douglas MD-80 series jets in 1985 that it had had to replace even one of the jackscrews, a key control mechanism in the tail.

The jackscrew problem surfaced after the airline switched lubricating grease and after it stretched the time between wear checks on the jackscrew as well as the interval for lubricating it.

"Unfortunately, it (the computer) did not react in time to tip us off there may be a problem with the jackscrews," Wright McCartney, reliability and maintenance program manager for Alaska, said of the computer-generated maintenance alert.

Testifying before the National Transportation Safety Board, McCartney said the alert did not suggest the kind of catastrophic jackscrew failure that occurred on Flight 261, so even if the alert had been issued earlier, it would not have predicted the crash.

"Never in the history of the industry . . . has there been a catastrophic failure of a jackscrew like occurred in this aircraft," he said. "I don't see how we could predict it, no."

Still, the revelations yesterday stunned family members attending the board's first public hearings into the crash.

"It was really disturbing . . . very upsetting," said Claire Barnett of Seattle, whose two daughters, Cori and Blake Barnett Clemetson, died in the crash Jan. 31, along with 86 others. More than half the victims were from the Seattle area.

Another family member, who asked not to be quoted by name, said she was "angry and dismayed" by what she has heard, not just yesterday, but since the hearings began Wednesday.

Alaska had 35 MD-80 jets in its fleet before the crash of Flight 261, so the three jets with the worn jackscrews represented nearly 10 percent of the carrier's total fleet.

Investigators believe the jackscrew mechanism in the plane that crashed failed because it was badly worn and may have lacked adequate lubrication.

A lead mechanic had ordered the jackscrew be replaced during a heavy maintenance check of the same plane at Alaska's Oakland, Calif., facility Sept. 27, 1997, but it was left in the plane after being retested by other mechanics and determined to be well within wear limits.

Questions have been raised by investigators about whether the $60,000 jackscrew assembly may have been left in the plane because replacing it would have delayed the jet's return to service, an allegation that Alaska officials have strongly denied. A federal grand jury in Oakland is looking into the matter as part of a criminal investigation that is separate from the crash inquiry by the safety board, which will not issue its final report on the crash, including the probable cause, until later next year.

Two witnesses were asked questions yesterday about the mechanics' decision not to replace the jackscrew of the jet that later crashed. One of them, Robert Hinman, received immunity from prosecution from the Justice Department before he would agree to testify.

Hinman was formerly director of base maintenance at Alaska's Oakland facility. He retired Oct. 1.

Jackscrews on MD-80s must be replaced if a so-called "end-play" check shows more than 0.040 of an inch of wear. The first test on the ill-fated jetliner found exactly forty-thousandths of an inch wear, and lead mechanic, John Liotine, ordered that it be replaced.

Hinman said he was not familiar with that order in September 1997. He also said he did not know if a replacement jackscrew was in Alaska's inventory at the time, or if the part would have to have been ordered. That would have kept the jet out of service for an even longer time.

But a couple days after the original inspection, another mechanics rechecked the jackscrew and got measurements that fell well within the wear limits. So the jackscrew was not replaced. The jet was returned to service.

Richard Rodriguez, the NTSB investigator in charge of the Flight 261 crash, pressed Hinman about those subsequent tests.

"Why would someone remeasure that? Isn't that a waste of manpower?" Rodriguez asked.

Hinman said he had no knowledge about the decision.

Art Fitzpatrick, director of base maintenance for Alaska and formerly line maintenance director in Oakland, also said he had no knowledge about the decision not to replace the jackscrew. Like Hinman, he said he did not know if there was a replacement jackscrew in Alaska's inventory.

When asked why the jackscrew had to be retested several times, Fitzpatrick said it was his understanding that the initial test had been performed by an "inexperienced" mechanic.

In testimony earlier, McCartney said maintenance workers first noticed unusual wear on the jackscrew of a MD-80 that was undergoing heavy maintenance in June 1999. That jackscrew failed the end-play test.

In November 1999, the jackscrew of a second Alaska plane was replaced after it failed the end-play test during a heavy maintenance.

A third jackscrew was removed in November during a heavy maintenance check by a third party in Phoenix. But the replacement part was not installed until January of this year.

After all those planes were returned to service -- the last in January -- a computer-generated statistical analysis of maintenance triggered an alert Feb. 3, just three days after the Flight 261 crash.

That formal alert meant mechanics were to pay particular attention to the condition -- and lubrication -- of jackscrews.

McCartney's testimony came on the third day of the NTSB's hearing into the crash and on a day when the pace quickened considerably. In addition to McCartney, the NTSB heard from witnesses about Alaska Airlines' decision to use a different kind of grease to lubricate the jackscrew.

Later in the day, the panel examined the airline's maintenance procedures.

As on previous days, however, the NTSB's gaze remained fixed on the jackscrew assembly and the stabilizer at the rear of the plane it controls. While investigators believe a failed jackscrew caused the crash, they are unsure about the conditions that caused the part to fail. A prime goal of the hearing, which is expected to end today, is to collect evidence to determine the conditions and practices that lead up to the failure.

The stabilizer, which resembles a small wing on the plane's tail, controls the up and down pitch of a plane and allows pilots to maintain level flight.

Wreckage from Flight 261 showed that the threads on the jackscrew were stripped and that large sections of the rodlike assembly were not lubricated.

Since the crash, Alaska has shortened the time that the jackscrew can be used without new lubrication. That directive to Alaska and other carriers was issued by the Federal Aviation Administration.

At the time of the Flight 261 crash, The Boeing Co. was recommending end-play checks on MD-80 jackscrews every 30 months or 7,200 flight hours, whichever comes first.

In 1996, Alaska had received approval from the FAA to drop the hourly requirement. About the same time, Alaska began operating its jets more hours per day as traffic demands grew.

The jet that crashed had flown for 8,884 hours since its last jackscrew wear test.

Seattle P-I

-- spider (spider0@usa.net), December 16, 2000.

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From the GICC archives

UPDATE - FAA Working to Improve Inspection System Flaws Criticism after the ValuJet crash in 1996 in the Florida Everglades was so sharp that the FAA completely revamped its maintenance inspection program. But while that new program, called the Air Transport Oversight System, has gotten good marks for its intent, it has stumbled in practice, congressional investigators found last year.

The new inspection program was designed to give federal aviation regulators a better overall picture of an airline's operations. Instead of inspecting individual aircraft, government inspectors are now expected to monitor how an airline maintains its fleet by using sophisticated computer systems.

. . .

Nick Lacey, the FAA's director of flight safety, said Thursday that he was ''disturbed'' that the new program had failed to adequately keep track of issues at Alaska.

. . .

Alaska officials, who have taken numerous steps to improve maintenance in the wake of the FAA's actions, insist that none of the problems has compromised safety on a flight.

GICC

-- spider (spider0@usa.net), December 17, 2000.

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But the airline's computer programming that tracks mechanical trends did not warn the airline until three days after the crash that three of the MD-80 series two-engine jets needed jackscrews replaced in 1999. SacBee

-- spider (spider0@usa.net), December 17, 2000.

Alaska Airlines maintenance software failure

-- Paula Gordon (pgordon@erols.com), February 20, 2001

Answers

The NTSB and the FAA have lost all credibility after the sorry investigation conducted on TWA flight 800. The NTSB still clings to the notion that the boost pump in the wing caused the explosion. There is an outside chance this could happen but probably did not occur. Now most cars have fuel pumps in their gas tanks and I am certain that some of these pumps have shorted to ground over the years but how many times have cars exploded. The NTSB did not find that imfamous boost pump in the sea but they still without facts cling to this absurd conclusion. Now this notion that the jackscrew caused this Alaska Airlines plane to crash is another one of their light-headed conclusions. So they find a jacksrew--jackscrews also control the flaps--at the bottom of the ocean after the plane hits the water at God only knows what speed and draw the conclusion that this is the culprit. I wish the NTSB would set up a test platform with a jackscrew and sevomotor and see if this servo can strip the threads. Jackscrews are about an 1.5 inch in diameter and are made from very hard steel. They also have acne threads which means they are very rugged. This type of thread is found on most house jacks. What happened to the limit sensors that stop that servomotor from jacking the screw too far. There is a feed back loop on all these systems and if the jackscrew positioned itself too far forcing the stabilizer to an extreme position something, namely a computer, sent the instructions. As I have mentioned before the flight controler sends out these commands. What galls me more than anything is we pay these nincompoops for this tripe and still the families do not know why this plane crashed.

-- David Williams (DAVIDWILL@prodigy.net), February 20, 2001.

Maybe lawyers will get to the bottom of it.

CNN

FAA, DOT face lawsuits over Alaska Airlines crash

LOS ANGELES, California (CNN) -- Families of victims of last year's Alaska Airlines crash are suing two government transportation agencies. Thirteen families are filing claims against the Federal Aviation Administration and the Department of Transportation over the crash last year, alleging that the federal agencies failed in their oversight roles.

The families say the FAA and DOT failed to ensure compliance with applicable maintenance regulations, failed to implement the Air Transportation Oversight System (ATOS) program and negligently certified the jackscrew assembly without the required redundancy.

"There is no other way to force the FAA to adequately do its job of overseeing the carriers of this country and enforcing aviation safety," said attorney Mary Schiavo.

(snip)

-- Rachel Gibson (rgibson@hotmail.com), February 20, 2001.


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