A 1940s-era seaplane that lost a wing during takeoff and crashed within sight of the beach, killing all 20 people aboard, had undetected cracks in its airframe that apparently caused the aircraft to break up, federal investigators said Wednesday.
After the discovery was disclosed, Chalk's Ocean Airways voluntarily grounded its fleet of four planes for inspection. All four planes are the same model as the one that crashed.
The cracks were found in the main support beam of a wing that fell off the seaplane shortly after it took off for the Bahamas on Monday.
As salvage crews and divers worked to haul the wreckage from a channel just off Miami Beach, investigators focused on how the cracks escaped notice by maintenance crews.
Authorities also recovered the plane's cockpit voice recorder, which was sent along with part of the beam to the National Transportation Safety Board in Washington. The recorder, however, was unreadable for an unknown reason, said Mark Rosenker, acting chairman of the NTSB.
Rosenker said the cracking in the 58-year-old seaplane should have been found and repaired, though the cracks could not be seen with the naked eye and it would have taken "a very serious" inspection to find them.
If Chalk's officials had known about the cracking in the Grumman G-73T Turbine Mallards "they would have repaired it and we wouldn't be here today. I don't think they knew it," Rosenker said.
Investigators planned to scour maintenance and flight records for evidence of work done.
The Federal Aviation Administration took no immediate action against the airline.
"These are trying times for this great airline. But we will be back in the air very soon," Chalk's general manager Roger Nair said in a statement. He did not return phone messages seeking additional comment.
Rosenker said the age of the plane built in 1947 could have been a factor in the cracking. The aircraft was retrofitted in the 1980s with more powerful engines, but it was not clear whether that played any role in the cracking, Rosenker said. Both engines were operating when they hit the water, he added.
At the time of those modifications, the airplane "would have a thorough inspection to make sure that it was a suitable aircraft to be modified," said Joseph Frakes, assistant manager of Frakes Aviation, the company that installed the new engines and refurbished the seaplanes. He declined to give further details because his company is part of the NTSB investigation.
Finding such damage would require "very sophisticated testing," such as a special dye that penetrates the aluminum structure, said Bill English, NTSB investigator in charge of the crash investigation.
Some additional stress on the airframe must have contributed to the cracking because age alone would not cause it, Rosenker said.
Crews used a crane Wednesday to lift out of the water the plane's left wing, an engine, a propeller, and parts of the fuselage and landing gear. The right wing was removed Tuesday.
Chalk's, which flies between Florida and the Bahamas, has lost hundreds of thousands of dollars in recent years, according to the federal Bureau of Transportation Statistics. In 2002, the latest year available, Chalk's had net losses of $244,000 on operating revenue of $5.4 million.
Owner Jim Confalone bought Chalk's after it was forced into involuntary bankruptcy in 1999 under previous management.
Associated Press Writer John Pain in Miami contributed to this report.
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