FAA Orders Jet Tail Inspections

The Federal Aviation Administration ordered the inspection of more than 1,100 airliners after metal shavings were found Thursday in the horizontal stabilizer mechanisms of two jetliners like the one that crashed last week off Anacapa Island, officials said.

The discovery suggests that the problems afflicting the Alaska Airlines MD-83 that crashed may affect others among the more than 1,900 similar planes now flying worldwide.

The FAA isn’t grounding all the U.S.-registered DC-9, MD-80 series, MD-90 series and Boeing 717 airliners that use the mechanisms, but the agency is demanding that the planes be checked within two to three days.

Officials say that because of the number of planes affected, the inspections could snarl traffic for a day or more, especially for giant American Airlines, which flies 284 of the sleek, twin-engine jetliners.

“I think the average member of the traveling public will understand the delay,” said Tom McSweeney, an FAA associate administrator.

Foreign officials are expected to issue similar orders governing their air carriers within a few days.

The bronze slivers found Thursday at Alaska’s Seattle and Portland, Ore., maintenance facilities apparently had been stripped from the gimbal nut that rides the stabilizer’s jackscrew--a thick, threaded bolt about two feet long.

The spinning jackscrew moves up and down through the nut, raising and lowering the leading edge of the stabilizer--the wing-like part of the tail of the jetliner that controls the up-and-down pitch of the plane’s nose.

In radio conversations with maintenance personnel and air traffic controllers, the pilots of Alaska’s ill-fated Flight 261 said they were having trouble controlling their plane because of problems with the stabilizer.

The stabilizer eventually jammed in the nose-down position, and 12 minutes later, despite the pilots’ frantic efforts to control the plane, the MD-83 spiraled down into the Pacific, killing all 88 on board.

On one of the planes in which damage was found Thursday, the shavings were embedded in the threads of the jackscrew and twisted around the screw like a curl of wire. On the other plane, the shavings were found in the grease that lubricates the mechanism. Neither plane had reported stabilizer problems before the inspection. The planes, apparently manufactured sequentially in 1997, have both been grounded.

McSweeney stressed that thus far, investigators have not determined how the shavings were stripped from the nuts. Aviation safety experts have suggested inadequate lubrication, misalignment, the failure of an automatic shut-off, or contamination by foreign material.

The National Transportation Safety Board said similar shavings--also apparently from the gimbal nut--were found twisted around the jackscrew recovered earlier this week after Alaska Airlines Flight 261 crashed.

The safety experts said much of the damage found on the jackscrew from Flight 261 probably occurred well before the fatal plunge. They said that damage could have worsened until the elevator jammed, setting off an as yet undetermined chain of events that led to the crash of Flight 261. Why the damage to the three planes was not spotted earlier, during routine maintenance before the crash, was not immediately clear.

“I don’t have an answer for that,” McSweeney said.

He said the jackscrew mechanisms haven’t had a history of problems, and under FAA regulations they are inspected only once every two to three years.

Alaska maintenance officials said their “C” check inspection interval wasn’t quite that long--more like every 15 months.

McSweeney said the failure to detect the problems earlier may just be “a timing issue.”

“The problem wasn’t there before, but it is now,” he said.

Alaska, responding to a request from Boeing Co.--which has taken over McDonnell Douglas, the firm that built most of the planes--began checking its 34 MD-80 series jetliners Thursday morning, finding the problems on two of them.

American began its checks Thursday afternoon, as did many other airlines that decided not to wait for the mandatory FAA airworthiness directive to take effect this morning.

There were no other reports of problems.

“We have found nothing,” said Sarah Anthony, a spokeswoman for Continental Airlines, which flies 69 MD-80s.

“Nothing so far,” said John Kennedy, a spokesman for Delta Air Lines, which already had checked more than 100 of its MD-80s and MD-90s.

McSweeney said the checks were being done at maintenance facilities with the necessary equipment, including a working stand or a “cherry picker” lift tall enough to reach the top of the tail, where the access door to the stabilizer mechanism is located.

“It takes specialized tools . . . to do this job,” he said. “We want it done right. We want it done thorough.”

The Navy reported Thursday that it had found and recovered some more pieces of the tail from Flight 261 while mapping the main debris field on the ocean floor about three miles north of the east end of Anacapa. Several other pieces of the tail assembly, including the jackscrew and its gearbox, were found Tuesday night.

An undersea search has begun about four miles away for another piece that apparently broke off the plane just before its final dive. What that piece may be has not been determined.

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Times staff writer Ricardo Alonso-Zaldivar in Washington contributed to this story.

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FAA Orders Inspections

On Thursday, the FAA ordered all airlines that fly MD-80 and related aircraft to inspect them. Here is a breakdown of the number of MD-80s, MD-90s and DC-9s flown by major airlines.

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*Includes entire MD-80 series

Sources: Air Transport Assn.; individual airlines

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Shredded Threads

Bronze shavings, found inside the nut assembly of two jets, prompted inspection of more than 1,100 aircraft.

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Source: The Boeing Co.; compiled by RICHARD O’REILLY/Los Angeles Times