April 17, 2011

Scrutiny Lags as Jets Show Effects of Age

By CHRISTOPHER DREW and JAD MOUAWAD

In April 1988, when the cabin roof ripped off an Aloha Airlines 737 and swept a flight attendant to her death, it sent a startling signal to the airline industry about the dangers of metal fatigue. Airlines immediately stepped up inspections of aging jets. Federal regulators cut up old planes to look for the spots under the most stress. And Boeing redesigned the joints that hold its 737s together.

They thought they had solved the problems.

But the five-foot hole in the roof of a Southwest Airlines 737 this month and other recent incidents indicated that they had not. In fact, a stream of safety directives from the Federal Aviation Administration in the years since the Aloha incident shows that structural cracks from metal fatigue remain a persistent problem on older planes.

Chillingly, the agency said in one directive that the discovery of some of the most serious damage had been “a purely random occurrence.”

Safety experts say that the industry and regulators rely far too much on a patchwork of rules that are largely reactive: each time a problem in one part of the plane is found, inspectors add that area to their checklists. Late last year, the F.A.A. itself acknowledged the seriousness of the issue when, for the first time, it issued a rule to set flying limits for aging aircraft. “The potential for catastrophic structural failure,” it said, “is very significant.”

Even so, the F.A.A. took more than four years to write the rule, as airlines objected that it would reduce the value of their planes and force them to ground some they thought could still fly. In response, the F.A.A. toned down the rule, extending a deadline for plane makers to come up with the lifetime limits.

John J. Goglia, a former member of the National Transportation Safety Board, which investigates accidents, says the F.A.A. needs to do more than wait for the industry to set plane-retirement deadlines and rely on the airlines to do piecemeal inspections. The Southwest incident showed, he said, that the agency should order thorough inspections of a couple of the older and most heavily used 737s, using the latest technologies, to determine where cracks might develop.

Right now, he said, “it looks like you’re putting Band-Aids on the airplane.”

Referring to both the Southwest incident and an earlier one in 2009, in which an 18-inch hole appeared in another Southwest 737, he said, “Here’s a case where we have a small hole, a big hole and if we’re not going to do something serious about the entire airplane, we’re going to end up with a smoking hole.”

F.A.A. and industry officials say they are reviewing their policies on aging planes. But they note that fatigue problems have not caused any deaths on jetliners since the Aloha accident, even with millions of flights a year in the United States.

J. Randolph Babbitt, the head of the F.A.A., and Boeing officials said last week that it was too early to conclude that the latest Southwest incident stemmed from metal fatigue. He said investigators were also examining Boeing’s manufacturing processes and other possible causes.

But whatever the outcome of the investigation, the older 737s have provided an early warning about the kinds of fatigue damage that other planes could eventually face. They have been sold since 1968, although the Southwest planes that have had problems are part of the series that was redesigned after Aloha, built from 1993 to 2000.

The 737 has been an industry workhorse because it is economical for both short and long trips. These planes tend to accumulate the highest number of flights. And given the weak financial state of the industry, some airlines have held on to them longer.

But engineers have long known that metal fatigue can develop as a plane’s cabin is pressurized then depressurized over tens of thousands of takeoffs and landings. Crucial parts of the fuselage can develop cracks, much like a paper clip that snaps after being bent back and forth. It is when many small cracks link up that they pose a danger.

The Aloha plane had flown nearly 90,000 flights. Boeing had pleaded with the carrier to ground its most-used planes and fix corrosion problems. Federal investigators faulted Aloha’s poor maintenance practices for the accident.

But this also led Boeing to redesign, twice, the glued and riveted joints that hold the overlapping pieces of skin connecting the top of the plane to its sides. Boeing figured that this design would last for at least 75,000 flights and would not need to be inspected for cracks until about 60,000 flights. (Designs of the 737 after 2000 eliminated the need for these lap joints.)

The damage on the roof of the Southwest plane, which suddenly appeared midflight on April 1 and forced an emergency landing in Yuma, Ariz., baffled safety experts because the jet, at 15 years old, had logged only about 40,000 takeoffs and landings. The F.A.A. ordered more frequent inspections of those joints starting at 30,000 flights.

Southwest checked 78 similar planes in its fleet and found five others that had developed single small cracks in various spots at just over 40,000 flights.

Boeing said on Sunday that inspections on several dozen other planes, mostly owned by foreign carriers, had not found any cracks. It said it was premature to say whether the cracks on the other Southwest jets were related to the problems that caused the hole on the April 1 flight.

Since 1988, the F.A.A. has issued nearly 100 directives tied to widespread fatigue, requiring airlines to look for cracks in various locations on a variety of airplane models. A quarter were described as urgent. The agency has listed about a dozen serious incidents over the past 16 years, including cracks that were found by people painting planes.

It said, for example, that airline inspectors had found substantial cracks in a bulkhead on a midsize Boeing 767 in 2003, and in fuselage frames of an Airbus A300 in 2002 and a jumbo Boeing 747 in 2005. The most recent incidents, since 2007, have involved the single-aisle 737s and 757s. At least nine have involved areas of the fuselage where overlapping sheets of metal are thinned out to help decrease weight.

In November, an American Airlines 757 depressurized after a two-foot hole opened over a door, forcing the crew and 154 passengers to put on oxygen masks. The plane quickly returned to Miami. Boeing had recommended inspections in that area by 25,000 flights; the plane had 22,000.

Most experts agree that huge progress has been made since the Aloha incident in 1988. Still, in 2007, an F.A.A. inspector allowed Southwest to operate 1,450 flights even though 46 of its planes had not been inspected for cracks in nine months. Southwest was fined $7.5 million for violating federal safety mandates.

The Department of Transportation’s Office of Inspector General reported last December that the F.A.A. had failed to make 576 safety inspections from 2005 to 2009. Even though the F.A.A. had cut the number of planned inspections in half over the last 10 years, the report noted, some were eight years late.

The F.A.A. says that it seeks to prevent fatigue through rules governing things like aircraft design and maintenance and that pilots are also trained to handle emergencies that could be caused by fatigue.

In the rule issued late last year, the F.A.A. sought to determine the time before widespread metal fatigue could affect the entire aircraft. F.A.A. officials said the agency was still considering a separate rule on some of the objections raised by the airlines. The agency is still awaiting more testing from the manufacturers to determine what the lifetime flying limits of planes should be.

But ultimately, the answer to combating metal fatigue on older planes may simply come down to economics, aviation experts say. An improving economy, combined with concerns about fuel efficiency given high oil prices, is once more prompting airlines to buy new planes. Southwest, for one, plans to phase out its older 737-300s with bigger planes that are more affordable to fly.

9-Hour Breaks Mandated

The transportation secretary, Ray LaHood, said that required rest time for air traffic controllers would be increased to nine hours to help prevent workers from falling asleep on the job.

“We’re going to make sure that controllers are well rested,” Mr. LaHood said in an interview on Fox News Sunday. “We cannot allow controllers to fall asleep.”

The F.A.A. suspended an air traffic controller on Saturday “for falling asleep while on duty” at night at the Miami Air Route Traffic Control Center.

New scheduling rules have been put in place and will be fully in effect by the end of the week, according to a statement posted on the F.A.A. Web site on Sunday.