Two Doomed 767S Were Partners On Assembly Line

They were identical models, the 282nd and 283rd planes off the 767 assembly line at Boeing's Everett factory in fall 1989. Both were 767-300ERs, extended-range versions of the twin-engine jetliner.

And they met identical fates.

No. 283 was delivered to Austria's Lauda Airlines in October 1989. Less than two years later, on May 26, 1991, it crashed in the jungle outside Bangkok, Thailand, killing all 223 people on board.

No. 282, delivered to EgyptAir in September 1989, was the plane that plunged into the Atlantic Ocean off the coast of Massachusetts yesterday, killing all 217 on board.

There were other similarities between the two crashes, though they were eight years apart.

Like EgyptAir's cockpit crew, Lauda Air Capt. Thomas Welch, a Seattle native, and Austrian First Officer Josef Thurner issued no distress signals.

In the Lauda crash, Thai authorities ultimately determined that an engine braking device, called a thrust reverser, inadvertently deployed, heaving the 206-ton Lauda jet into a furious, supersonic dive.

The Lauda jet's cockpit voice recorder captured Thurner saying, "Ah, reverser's deployed," followed moments later by sounds of the jet breaking apart.

As U.S. investigators gathered in Rhode Island this morning, recovery of the EgyptAir's cockpit voice recorder and flight data recorder took on heightened significance. The voice recorder holds telling cockpit noises and conversation, while the flight data recorder logs detailed information about the jet's moment-to-moment movements.

`A very rapid descent'

With jet debris scattered on the ocean floor, all possibilities remain open, including a terrorist's bomb or some combination of weather effects, pilot error or mechanical malfunction.

"We do not know at this point what caused this crash," National Transportation Safety Board Chairman Jim Hall said yesterday.

But Hall also noted that local radar tracked EgyptAir 767 routinely cruising at 33,000 feet one moment, then plummeting to 19,100 feet - 2.6 miles - in the next 36 seconds, in what he described as "a very rapid descent."

Radar similarly tracked the Lauda jet careening from 24,700 feet to about 8,000 feet - 3.1 miles - in less than 30 seconds. From sounds captured in the final hundredth of a second on the cockpit voice recorder, investigators deciphered the jet breaking up at speed and forces it was not designed to withstand.

FAA ordered fixes

In 1994, three years after the Lauda crash, the Federal Aviation Administration ordered a series of major thrust-reverser fixes for all U.S.-registered 767s. Foreign carriers, like EgyptAir, typically abide by such FAA-mandated upgrades, though they are not strictly required to do so.

The EgyptAir 767 did undergo that modification, Maged el-Masri, EgyptAir vice president for technical affairs, told The Associated Press today. He said the modification was made in 1993 at a British Airways workshop in London.

Even so, investigators will still explore whether some type of mechanical failure involving the thrust reverser or some other system came into play.

Initially, though, they are likely to focus most closely on the EgyptAir-Lauda parallels.

"The similarities certainly scream out between this crash and Lauda Air," said Terry Ford, a Santa Rosa, Calif.-based aviation consultant who helped investigate the Lauda Air crash for victims' families.

The Lauda investigation

Thai investigators in 1991 initially thought a terrorist bomb brought down the Lauda jet. In the weeks following the accident, speculation on the cause ranged from catastrophic engine failure to spontaneous combustion of a crate of lithium wristwatches in the cargo hold.

Adding to the confusion was the fact that the airplane crashed in a remote jungle hillside 130 miles from Bangkok, and villagers looted the wreckage.

However, a crucial piece of evidence emerged when the left engine was recovered with its thrust reverser in a fully deployed position. Reversers slow a jetliner by diverting engine thrust forward, and are designed to be used only on the ground as a supplement to the wheel breaks.

Even with the deployed reverser as evidence, investigators thought the pilots should have been able to maintain control of the aircraft.

Airline owner Niki Lauda, a seasoned pilot, accepted that line of reasoning after flying through a reverser deployment in a Boeing 767 simulator in London. A week after the accident, Lauda said he thought that a bomb or fire caused the crash.

Then, in August 1991, Boeing lab technicians discovered how a worn seal could cause the directional control valve to misdirect pressurized fluid and deploy a reverser during flight.

The finding prompted the FAA to order a ban on use of reversers like the one used on the Lauda 767. Still, the FAA was not yet willing to completely blame the reverser because Boeing continued to maintain that pilots should have been able to fly the aircraft, even with the left reverser deployed.

However, the NTSB pushed Boeing to recalculate its aerodynamic formulas predicting how a 767 would behave if a reverser deployed.

Fresh data from new wind-tunnel tests showed a reverser deployment was apt to plunge a plane furiously out of control.

The data were fed into a 767 simulator in Seattle, and airline owner Lauda was brought in to fly it. Lauda told news reporters after the simulation that, upon deploying the left reverser, the simulator twisted and flipped completely over to its left in a couple of seconds. A few seconds more and it was careening, nose aimed down.

"You're suddenly upside down in a dive," Lauda said. "There's nothing you can do. It turns over, then it goes nose down. You go right into overspeed, and then you lose all of your controls. The airplane broke up at exactly 17 seconds after it went out of control."

In 1994, the FAA ordered extra locks for reversers on all late model Boeing 767s, 737s and 757s registered in the United States. The agency also ordered upgraded directional control valves installed in some 757s and substantially modified wiring and directional control valves on 767s with the same type of engines as the Lauda airplane.

Autopilot glitches

Beyond the thrust reverser, another possible scenario for investigators could involve the 767's autopilot controls, which have a history of troublesome glitches.

NTSB records point to 29 incidents of "uncommanded autopilot engagements, disengagement, mode changes" and control panel changes on 757s and 767s which used autopilot systems built by Collins Avionics of Cedar Rapids, Iowa.

In October 1993, the safety board called on the FAA to order airlines to remove all power from the Collins autopilot systems when not in use and to inform pilots about the possibility of such malfunctions.

Boeing opposed the recommendations, though it initially could not pinpoint a cause for the autopilot glitches.

Then, in June 1995, the FAA advised the NTSB that a batch of 106 mode control switches, parts of the autopilot, were defective. The FAA warned the flaw "could produce an intermittently open circuit" that could cause the autopilot to engage inadvertently.

Collins and Boeing issued advisories for airlines to test and replace the faulty switches. And a Boeing survey submitted to the FAA indicated all of the faulty mode control panels had been modified. The FAA determined the problem was not "flight critical" and took no action.

Seattle Times reporter James Grimaldi and research specialist Justin Mayo contributed to this story.

Byron Acohido's phone message number is 206-464-2352. His e-mail address is: ------------------------------- Boeing 767-300ER

Teh boeing 767-300ER that disappeared early yesterday is the company's longest-range aircraft and the type most commonly used for trans-Atlantic flights.

Delivered to the airline: September 1989. It had logged over 30,000 flight hours and 6,900 takeoffs and landings.

Configuration: Two-aisle, twin-engine aircraft. Range: Up to 7.",080 miles.

Capacity: Upt to 218 passengers ina three-class cabin.

Max. gross weight: 300,000 pounds for the basic 767.

767 history: Estimated to have carried 813 million passengers on more than 3 million flights since it first entered service on Sept.l 8, 1982.

767-300 history: Program got under way in September 1983. The model is longer than earlier versions by more than 21 feet and has 20 percent more seating capacity.

SOURCE: The Boeing Co. ------------------------------- THE ASSOCIATED PRESS.