Three days earlier expands cracks in a five foot hole in the roof of a Southwest Airlines flight, forcing the aircraft, a 737-300, to make an emergency landing at a military base, undetected. The F.A.A. announcement applies 175 aircraft worldwide, including 80, based in the United States. Most are operated from the Southwest, which started controls over the weekend and found three more aircraft with small cracks.
The airline canceled also 70 flights from its schedule 3,400 runs on Monday. About 300 flights were cancelled on Saturday and Sunday.
The incident on Friday was the third with metal fatigue at least in the last few years, and the most horrible. The other parties involved other Southwest 737-300, flight in 2009 and an American Airlines Boeing 757 in the last year.
The recent string has confused similar problems of security experts who said that industry assumes that it flew from Aloha Airlines successfully had solved the problem of metal fatigue after an accident in 1988 with a 737 Jet. During the flight, an 18-foot section was opened the forward cabin and a flight attendant of the level.
Southwest to insisted that it had done the necessary inspections of its aircraft. But the last issue focused on how the carrier its aircraft up to 12 flight used segments per day. Other airlines which fly longer routes, have usually six to eight segments for their aircraft. The aircraft the incident Friday involved had logged, 39,000 take-offs and landings, a relatively large number of 15-year-old aircraft.
The F.A.A. focused directive on aircraft had accumulated a large number of takeoff and landing cycles. It applies not only to the 737-300 model, but also similar 737-400 and 500 models, a design, which comes from the early of 1980s and is known as the 737 classic series.
"It was a very serious error," said William R. Voss, the President and Chief Executive of the flight safety Foundation, an independent non profit group. "There are wrong with something we have in the past 20 years the inspections, or was there something wrong on the inspection with a level?"
Hans j. Weber, owner of Tecop international, a consulting firm of aviation in San Diego, said that jetliner could easily survive a small crack in the aluminum skin on the body. But what happens in the Aloha accident and the recent events is that several small cracks in nearby rivets in areas where the level gives the most stress experience, the skin again withdraw. "It's like it the decompress," said Mr Weber.
The F.A.A.-directive to detect cracks in places where the skins overlap and other structural weaknesses, j. Randolph Babbitt, the F.A.A. administrator, said in a statement. The directive came shortly after Boeing, manufacturer, said, it was also recommend airlines where the skin covers joints on the older models of 737 examine the areas.
The National Transportation Safety Board, which incident leads an investigation on Friday, said that it was probably the result of fatigue cracks in these connections. Southwest began flying the aircraft, carrying 1996 118 passengers, and it is one of the oldest in their fleet.
Mr Weber, said that after the accident of Aloha, metal fatigue was a big problem, and the F.A.A. began carrying out more frequent and intense inspections airlines as aircraft in the age and collected more takeoffs and landings to demand.
"In recent years, the attitude that we solved the fatigue problem," he said. "But we see what happens when attention on anything that moves, that we a little slip the quality of the work we do?" "This is just speculation, but that's what I am concerned."
Whitney Eichinger, a spokeswoman for Southwest, said the airline in accordance with all F.A.A and Boeing control requirements was. "Security very seriously as we our people take maintenance, which is why our safety record is so solid," she said.
An expert, John j. Goglia, a former N.T.S.B.-Chairman, said that that could lead flight 812-episode, to change airlines for metal fatigue look like. "The crack formation for a long time is known," he said. "It is nothing new." "What could be new finds it at this point."
But Mr. Weber said, that also if the precise location of previous incidents difference, the fact that it has occurred in the roof of the level "no surprise." He added: "Everybody knows that the highest load are in the Crown."
This is not the first time that a plane was a crack in the flight Southwest. In July 2009, another level developed a skin fatigue problem that causes a small puncture in the fuselage.
And in the last year, Boeing 757 an American Airlines experienced a sudden decompression, after a 1-foot by 2 foot left a hole in the hull in the upper Crown above the open door. This prompted the F.A.A., a new certificate of airworthiness issue directive require that repeated inspections of more than 680 757 s of airlines in the United States operated. The last F.A.A. directive requires initial inspections, with called eddy currents, inspectors cracks in the 300, detect low voltage electrical currents, help those 737 s 400 and 500 series, collected more than 30,000 were flight cycles. It is then "repetitive inspections" at regular intervals require. More details are expected Tuesday, when the directive is formally released.
Mike Boyd, who said Chief Executive of the Boyd Group, an aviation consultant, that while the episode Southwest traumatic, can seem especially for passengers on board, they are in fact, extremely rare and would not have much impact on how their run Southwest or other airlines.
"You will find always cracks on an airplane, but I don't think this is going to be earth shattering anyone," he said.
