Detailed analysis of a jetliner that had part of its fuselage blown off while flying at 24,000 feet found cracks apparently caused by metal fatigue, a federal official said.
"What appears preliminarily to be fatigue cracking" was found at six rivet holes on a metal strip running the length of the aircraft, Joseph Nall of the National Transportation Safety Board said at a news conference Sunday night.The cracks, measuring 0.2 to 0.6 inch, were discovered on the metal strip, called the No. 10 stringer, that ran above the passenger windows on the left side of the Aloha Airlines' Boeing 737, Nall said.
Nall said all of the plane's rivets, as well as those on Aloha's other 737s, were being tested electronically in an effort to find any other cracks.
The plane made an emergency landing Thursday at the airport in this Maui Island town. The flight from Hilo to Honolulu carried 95 people, including 89 passengers.
Twenty feet of the plane's upper fuselage covering first-class passengers tore away. A flight attendant who had worked 37 years with Aloha, Clarabelle Lansing, 57, of Honolulu, apparently was sucked from the plane to her death, while 61 other people were injured.
Seven remained at Maui Memorial Hospital on Sunday in stable condition with burns and lacerations, nursing supervisor Beverly Perreira said.
The seven, who were sitting in the area of the rupture, mainly in window seats, received their cuts from jagged sections of what remained of the fuselage, Nall said.
They also suffered wind burn, he said.
Only 30 percent of the fuselage remained intact at the point of the rupture.
Nall said tests found that repairs made last November to two cracks in the plane's No. 4 stringer, located farther up the fuselage, appeared to have held.
A service bulletin issued by Boeing in April told airlines to look for corroding fasteners that hold pieces of the fuselage together.
Close inspection of the upper skin of early model Boeing 737s was ordered Oct. 5 by the Federal Aviation Administration after routine inspections turned up cracks near where sections of sheet metal overlap, officials said Friday. The agency warned the problem could cause rapid cabin decompression, they said.
Inspections carried out because of the FAA order turned up nothing unusual, said Aloha Airlines spokeswoman Stephanie Ackerman.
In the wake of the accident, the FAA has barred some of the oldest versions of the 737 from flying above 23,000 feet.
The order affects 66 plans, operated by Aloha, American and Piedmont airlines, that have made more than 55,000 landings. The Aloha plane, in service since 1969, had made 85,000 to 90,000 landings.
Air and sea searches failed to locate any trace of the missing fuselage section, officials said.