Signs Of Metal Fatigue In Crash

Investigators plan to scour maintenance and flight records in search of evidence that could show why a seaplane's wing broke off during flight, causing the plane to plummet into the water, killing all 20 people on board.

But they may already have a major lead, reports CBS News correspondent Bob Orr: metal fatigue.

"We've seen fatigue. We don't know why that fatigue appeared. That is what we're trying to determine," Mark Rosenker, acting chairman of the National Transportation Safety Board, said Wednesday morning. "This crack appears to extend through a majority of the spar at the location of the separation."

"This is very significant because it suggests the wing was badly compromised before it took off," Orr says. "While investigators still want to review all of the wreckage and the cockpit voice recorder, this discovery of metal fatigue is very close to a 'smoking gun.'"

Orr reports metal fatigue in aircraft isn't unusual, and may be the cause of this crash. (audio)

The propeller and engine were still attached when salvage crews raised the right wing from the channel Tuesday where the 58-year-old turboprop aircraft crashed.

The plane, headed to the Bahamas, crashed Monday into the mouth of Government Cut channel off the southern tip of Miami Beach within sight of horrified beachgoers. Investigators said Tuesday the crash was apparently caused when the wing broke off.

Crews planned to raise the rest of the plane from 35 feet of water Wednesday. Rosenker said the process would be slow and cautious because moving the plane too quickly could cause it to break under the weight of the water.

Rosenker said it's too soon to assign blame.

"Inspection maybe would have found that [metal fatigue], but there would have had to have been a very serious type of inspection to have understood it and found it," he said.

Amateur video of the crash is giving the NTSB a huge lead, reports CBS News correspondent Mark Strassmann.

"It's rare you get to see an accident while it's going on. So we believe there's a great deal of information to be gleaned from it," said Rosenker.

Investigators also hoped to recover the cockpit voice recorder to see if it captured the last words of the pilots and other clues. But the main portion of the recorder was in the tail, which Rosenker said was difficult to reach because the plane was mangled.

Specialists will try to determine whether corrosion and stress contributed to the wing splitting from the fuselage. It could take nine months to a year to report on the probable cause of the crash, Rosenker said.

"Unfortunately, we still have a great distance to go," he said.

Investigators went to Chalk's Ocean Airways' office to get the plane's maintenance and flight records, he said. The airline's owner, Jim Confalone, and general manager, Roger Nair, did not return calls for comment.

The plane's age is not necessarily a factor in the crash, Rosenker said.

Older airplanes have been a concern for federal safety officials since 1988, when fatigue cracking caused the roof of an Aloha Airlines Boeing 737 to peel off over Maui. A flight attendant was sucked out of the airplane and lost at sea. The Aloha 737 was 19 years old when the accident occurred, but it had taken off and landed more than 80,000 times.

That accident, and a subsequent law passed by Congress in 1991, prompted the Federal Aviation Administration to step up its requirements for inspections and maintenance of aging aircraft.

Eighteen passengers — including three infants — and two crew members were on the flight. Most of the people on that flight had been Christmas shopping in Miami, reports Strassmann. Weeping islanders went house to house Tuesday to grieve.

"The island at this time is in an uproar," said Walter Stuart of Miami, who lost 11 family members in the crash.

The plane was a twin-engine Grumman G-73T Turbine Mallard. It previously had few major reported incidents, and no passengers or crew were injured in any of them, according to the FAA.

Rosenker urged witnesses with amateur video or photographs of the crash to come forward.