Fastener Change Performed As Part Of 1991 AD

It now appears a Boeing 757 which lost a four-by-five-foot composite wing panel somewhere over Maryland late last month, suffered failed fasteners which were installed as part of an FAA airworthiness directive in 1991.

The National Transportation Safety Board says that missing panel -- which flew off the jet March 22, as ANN reported -- was never located, but adds the Board has found enough evidence in surrounding components to determine what happened to US Airways flight 1250.

"Initial examination of these components revealed that two of the three clips that secured the leading edge of the panel to the wing had failed due to metal fatigue sometime prior to the incident flight," the NTSB noted in an update Tuesday. "The remaining clip failed during flight 1250, causing the panel to separate from the aircraft."

The board added that a fastener change was mandated in an FAA airworthiness directive in 1991, and was completed on this particular 757 by its then-owner, Eastern Airlines. The board says it was the redesigned fasteners that failed on flight 1250.

Since the March incident, NTSB says inspections of all flying 757s has found problems with wing panel fasteners on several other aircraft, which have since been repaired and returned to service.

The loss of the panel has also been downgraded from an accident to an incident in official jargon, since the plane's flight data recorder revealed no adverse affect on the plane's handling after the panel detached. The debris did strike the side of the plane, however, causing minor damage to the fuselage and cracking the outer pane of a cabin window in row 19.

FMI: www.ntsb.gov, www.usairways.com