By,

JAMES WALLACE

SEATTLE, March 10 - A United Airlines 767-300 carrying 238 passengers lost power in both engines on a flight from Maui to Los Angeles last Sunday, but the pilots were able to restart the engines and land the big jet safely on the island of Hawaii, an airline spokesman confirmed yesterday.

The jet was flying at between 27,000 and 29,000 feet, according to the National Transportation Safety Board, which is investigating.

Both engines were out for only a short time, a board spokesman said. Investigators are analyzing the jet's flight data recorder.

It is very rare for a twin-engine commercial jetliner to experience a dual engine failure, aviation experts say. And it is usually the result of either fuel starvation or pilot error, they say.

The Boeing Co., manufacturer of the widebody jet, said it has received only four other reports of a 767 having lost power in both engines since the plane entered service in September 1982. During that time, the 767 has logged nearly 9 million flights.

"This is an extremely rare event," said Boeing's 767 spokeswoman Debbie Heathers.

The last occurred in 1987, when the pilot accidentally shut off both engines. Boeing subsequently moved the 767 engine control switches and placed guards over them.

Boeing and United, along with engine-maker Pratt & Whitney, are assisting in the investigation of what happened on United Flight 42.

United is not releasing details because of the NTSB investigation, said spokesman Joe Hopkins in Chicago.

But the Seattle Post-Intelligencer pieced together this account based on interviews and a sketchy report by the Federal Aviation Administration.

Flight 42, carrying 238 passengers and a crew of 12, left the Kahului airport on Maui about 1 p.m. local time, bound for Los Angeles.

About 70 miles past Hawaii over the Pacific, one of the engines was shut down, possibly because it overheated. The second engine then quit.

The crew was able to restart both engines and the plane diverted to Keahole-Kona Airport on Hawaii, where it landed safely. No one was injured. The jet had minor wheel and brake damage from making an overweight landing because it carried so much fuel.

Hopkins said passengers were put on another flight and the 767 was ferried to San Francisco for testing before being returned to service.

Aviation safety expert and author John Nance of Tacoma said pilot error cannot be ruled out as the cause of the second engine shutdown.

"It's always possible there was a mechanical problem," he said. "But other than turning off the engine start switch or pulling the fire control handle, having an engine just quit would be so extremely rare an occurrence as to be almost unheard of. To have an engine on the 767 suddenly stop running with no actions by the crew just doesn't happen."

That view was echoed by Todd Curtis of Seattle, a former Boeing accident data analysis expert who manages the airsafe.com Web site.

"It's almost always either fuel exhaustion or inadvertent action by the crew," he said. "But restarting an engine is fairly routine as long as you have altitude."

Such was not the case with a Delta 767 that departed Los Angeles on June 30, 1987, with 205 passengers. The captain mistakenly moved the fuel control knobs to the off position. The plane, at 2,000 feet, dropped to only 500 feet above the ocean before the engines were restarted.

A year earlier, a United 767 pilot accidentally shut off both engines as the jet climbed through 3,000 feet out of San Francisco.

Boeing was already working on modifying the engine switch design, but that change had not been implemented on the Delta 767.

Two other dual-engine shutdowns occurred not long after the 767 entered service.

One involved an Air Canada 767 that ran out of fuel at 41,000 feet while en route from Ottawa to Edmonton in July 1983. The pilot glided the jet about 100 miles to a safe landing at a closed-down airport at Gimli in Manitoba. The so-called Gimli Glider incident became the basis for a television movie.

Lori Gunter, a Boeing safety spokeswoman, said there was one other case of a dual-engine shutdown on a 767 before Gimli, but she did not know the date. It was apparently a mechanical problem.

Nance, the aviation expert, said a 767 can glide in unpowered flight a distance that is equal to about 3.5 times its altitude. That means United Flight 42 could have glided more than 100 miles had the pilots not been able to restart the engines.

But an unpowered, or "dead stick," landing is tricky and dangerous. The plane lands much faster than normal and engine thrust reversers can't be used to slow the plane after touchdown.

And there is no room for error.

The engines on a commercial jetliner provide electrical and hydraulic power to the airplane. The hydraulic system is necessary to move flight control surfaces. Electrical power is needed for flight deck instruments.

The 767 has several backup systems in the event both engines quit.

A ram air turbine automatically deploys from the belly of the jet.

But it kicks in only after the engines have spooled down to a level where they can no longer produce electrical or hydraulic power. Until the jet's airspeed drops significantly, engine blades windmill from the rush or air, which produces some power.

There is also an auxiliary power unit in the tail that runs on batteries and can provide power.

"You are never going to be in a situation where you don't have the ability to fly the airplane," Nance said.

"With the backup systems, you should have minimum instrumentation and hydraulics even if you can't restart the engines."

But the pilots of an Ethiopian Airlines 767-200 were not so lucky after their hijacked jet ran out of fuel on a flight from Ethiopia to Kenya in November 1996.

The aircraft ditched in waters off the Comoros Islands. Ten of the 12 crew and 117 of the 160 passengers died, including the three hijackers.