Mon May 12 2003, 09:39 PMBF
FAA to Advise Crews on Smoke-Related Safety Procedure
FAA to Advise Crews on Smoke-Related Safety Procedure
By Don Phillips
Washington Post Staff Writer
Monday, May 12, 2003; Page A02
America West Flight 44 was cruising at 37,000 feet on its way from Phoenix to Washington on April 27 when passengers heard a muffled "thump" that seemed to come from below.
"I said to my seatmate, 'Uh oh, I don't think so,' " passenger John McCarthy said, simultaneously pressing the flight attendant call button. A few minutes later, there was a louder thump, "like someone hit the floor with a crowbar," said McCarthy, a private pilot and atmospheric scientist traveling to Washington for a meeting at the Federal Aviation Administration.
The cockpit crew heard the same sounds, and some instrument readings did not look right. The captain told the passengers he was sorry to interrupt the movie but the plane was diverting to St. Louis because of an "engine problem." What appeared to be an explosion then shook the left engine.
Thick smoke immediately filled the Airbus A319, so thick that the crew could not see the instruments and passengers could not see the people ahead of them. "It was stunning how fast it happened," McCarthy said.
Some screamed, some cried and some, including flight attendants wearing portable oxygen masks, moved about to comfort the panicked.
The pilots, pressing their oxygen masks against the instrument panel to see, programmed the computer into an unusually steep descent of perhaps 3,000 feet a minute toward St. Louis, aiming for the closest major airport as quickly as possible. So many alarms were going off that the crew initially could not tell whether their main problem was the engine or something worse: a fire in the cargo hold and the electrical bay beneath the cockpit.
Luckily, there was no fire, and 12 minutes later, the pilots managed to land and taxi to a gate, where the captain addressed the passengers to cheers and applause. There were no injuries.
The culprit was a bearing box, a part already known to be occasionally troublesome. There had been other failures, including three others on America West. The engine manufacturer, International Aero Engines, had previously urged airlines to periodically inspect the bearing box until the part could be replaced at the next scheduled engine overhaul. But until the Flight 44 incident, it was not considered a serious safety issue. None of the incidents had produced thick smoke, which turned out to be a thick oil mist rather than smoke produced by a fire.
The FAA, as early as today, plans to issue an "airworthiness directive" to advise crews how to prevent thick smoke from entering the plane when they are confronted by the same problem. The suspect boxes may be in 300 to 400 of the 2,100 engines of the V2500 model. They are used on some members of the Airbus A320 family and the Boeing 717, a smaller twin-engine plane being built as a replacement for the DC-9.
"We are now evaluating what to do about this," said Nicholas Sabatini, the FAA's associate administrator for regulation and certification. "We consider this serious."
Sabatini said the defect does give early warnings, such as the muffled thumps and a cockpit instrument indication that an engine oil filter is becoming contaminated with debris.
The Flight 44 incident, ironically, illustrates how safe aviation has become. In past years, crashes were caused by obvious factors such as pilot error, collisions with other aircraft or bad weather.
However, new equipment, better training and more sophisticated jetliners have combined to prevent crashes caused by such low-hanging fruit." Today, crashes are usually caused by a series of highly unlikely events that combine in just the right order to defeat even the most sophisticated safety equipment. This is usually called the "long thin chain." If any one link is broken, the crash does not happen.
In the case of Flight 44, the cockpit crew broke the chain.
The first link in the chain was something microscopic. Mark Sullivan, spokesman for Pratt & Whitney, one of the companies in the International Aero engine-manufacturing consortium, said that after problems began cropping up, engineers discovered that a coating applied to a shaft in some bearing boxes could flake off into tiny pieces and contaminate the bearings.
The bearings and shaft are sealed into a box that is filled with oil. Once the bearings are contaminated, they begin to vibrate. That can break the seal and allow oil to spew out into the high-pressure compressor at the front of the engine, the last stage before fuel is injected into the engine.
The clean, pressurized air from this area is injected into the aircraft to provide fresh air, heating and cooling. Therefore, hot oil mist from the bearing box can spew directly into the air in the cockpit and cabin.
The crew of Flight 44 donned oxygen masks as soon as they noticed this oil mist pouring into the right side of the cockpit. They declared an emergency, giving them air traffic control priority into St. Louis.
Joe Chronic, America West Airlines vice president for flight operations, said there was a series of alarms indicating smoke in the cargo hold and the electronics bay. The possibility of a fire in those areas had to be the crew's first priority, While the captain flew the plane, the first officer put his mask down to a screen to better read an emergency checklist.
"One emergency is enough," Chronic said. "When multiple things go wrong, you prioritize." He declined to identify the pilots.
The crew shut down the engine, continuing to fly on one engine, and within a few minutes the oil mist began to clear. After landing, the St. Louis tower informed them that no smoke or fire was visible outside the aircraft, so they decided to taxi to the gate rather than take a chance on injuring passengers by evacuating the plane on the runway.
"I think they did a magnificent job under very trying circumstances for a few minutes," Chronic said.
McCarthy agreed, as did other passengers, who could hear alarms and bells continuously as the plane descended. Many thought they would die. Instead, they stumbled, uninjured, off the plane into the concourse, hugging and cheering.
"From all I could tell, the crew performed admirably," McCarthy said. "And I felt the cabin crew did a superb job." http://www.washingtonpost.com/wp-dyn/articles/A42972-2003May11.html