Boeing Isn't Convinced On Engine Reverse -- It's Looking At Other Possibilities

A Boeing Co. expert on jet-engine thrust reversers has been sent to Thailand to join the probe of a fatal jetliner crash even though the company says it is not yet convinced that a wrongly activated reverser actually caused the accident.

Boeing said yesterday it has no plans to advise airlines to ground any of its 767 airliners, and the company seemed to play down an Austrian official's statement that a computer malfunction caused the crash.

A Boeing 767-300 operated by the Austrian airline Lauda Air crashed shortly after takeoff from Bangkok on May 26, killing all 223 people aboard. It was Thailand's worst aviation disaster and the first-ever crash of a 767.

Last night, John Nance, a Tacoma-based aviation safety expert, said the accidental deployment of a reverser, by itself, normally would not be enough to cause a crash. And Nance expressed frustration at the investigation and statements made by various parties.

"I've never seen an accident in which so many irresponsible statements have been made . . ." he said.

Frustration also is building for Boeing officials. Mark Hooper, Boeing Commercial Airplane Group spokesman, said his company's representatives in Thailand are having difficulty gaining access to the wreckage so they can make their own inspections. In addition, looters have removed much of what could be key pieces to the investigation.

"We still have a lot to analyze," Hooper said, "and we want to listen to the (cockpit) tape. Our investigation is far from over."

Austrian Transport Minister Rudolf Streicher said in a statement yesterday that a cockpit voice recording, being analyzed in Washington, D.C., indicated that a computer malfunction switched one engine into reverse and caused the jetliner to crash.

And at a news conference in Vienna, Niki Lauda, the owner of Lauda Air, also said he believes the crash was caused by an engine that suddenly reversed thrust. Lauda said the last words of the crew audible on cockpit recording was "it deployed" - apparently referring to the mechanism that he thinks sent an engine into a reverse thrust normally used for braking.

Lauda said he hoped the nearly 350 767-300s in service around with world will be inspected.

Boeing spokesman Randy Harrison said Boeing has not grounded any 767s and has no plan to do so because its investigation, so far, has not turned up evidence that it is necessary.

"Based on the reliability of this plane, we don't have any reason to do that," Harrison said. "On-site investigators believe there are other factors that must be examined, as well as the cockpit voice recorder data, before any firm conclusions about the cause of the accident can be drawn."

He noted that, as part of the 767's certification for commercial flight by the Federal Aviation Administration, Boeing had to demonstrate the plane could remain under control when a single thrust reverser is deployed in flight.

Thrust reversers on a 767 are a set of diverters and doors that open on the engines to deflect exhaust and act like a brake. On a 767, they are designed to be used only when the aircraft is on the ground, during landing.

Pressed on what other possible causes Boeing was looking at, Harrison would only say, "other phenomena, several of which are not connected in any way, shape or form with thrust reversers."

Streicher's statement said all Austrian operators had been ordered to carefully investigate such engines for faults. The Lauda jet was equipped with Pratt & Whitney PW4060 engines.

FAA spokesman Paul Steucke said the agency and the National Transportation Safety Board were helping the Thai government investigate the accident.

"We will issue warnings to owners and operators as soon as we can determine what the cause is," said Steucke.

Information obtained from the cockpit tape did not pose any problems that would prompt the NTSB or the FAA to recommend or order any new inspections of the engines or of the 767s themselves, Alan Pollock, NTSB spokesman, said today.

Aviation expert Nance said that while thrust reversers have accidentally deployed on other planes, he could not recall it happening before on a 767.

He said it is "ludicrous" to think an engine reverse thrust would be the principal cause of such an accident. "If it were pushing full force, it (the engine) would drop off the wing."

Nance said "there has to more here . . . possibly a human factor. Nothing must be ruled out." He said the idea that the engine caused the wing to break up "heightens the possibility that a bomb may have been involved. It could have been placed in or around the engine." Initially, there was speculation that the crash of Lauda Air flight 004 might have been caused by a bomb.

Nance was critical of the Thai and Austrian governments for their handling of the investigation, saying that politics is involved and that no one wants to accept blame.

Bob Goehring, a spokesman for engine maker Pratt & Whitney, said company officials have seen a transcript of the cockpit tape and heard nothing substantially different than what Lauda reported. But he stressed that it revealed only "pilot interpretation" of what was happening.

But Goehring said Boeing is looking at "something else," but he wouldn't say what it was.

The company has two experts in Thailand who have been allowed to visit the crash site only once in the week since the plane went down.

"We're having a dreadful time because authorities won't give us access," he said.

Goehring also said it "doesn't seem plausible that an engine going into reverse would break up a wing." He said Boeing manufactures the thrust reversers for the Pratt & Whitney engines and has a set procedure for how to handle them.

-- Times business reporter Polly Lane, and Associated Press and Reuters contributed to this report.