4.22.08 – Update on Investigation of 757 In-Flight Wing Panel Separation

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NTSB ADVISORY
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National Transportation Safety Board
Washington, DC 20594

April 22, 2008

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NTSB ISSUES UPDATE ON INVESTIGATION OF 757 IN-FLIGHT WING
PANEL SEPARATION

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In its continuing investigation of US Airways flight 1250 on
March 22, 2008, in which a wing panel, measuring about 4
feet by 5 feet, separated from the B-757, the National
Transportation Safety Board has developed the following
factual information:

Although the separated wing panel has not been located,
investigators have been able to examine the remaining
components of the assembly to determine why the panel
fastening system failed. 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
remaining clip failed during flight 1250, causing the panel
to separate from the aircraft.

After problems with the 757 wing panel fastening system were
identified in the late 1980s, the Federal Aviation
Administration issued an Airworthiness Directive (AD)
requiring operators of 757s to install a redesigned
fastening system. Eastern Airlines, which ceased operations
in 1991, operated the 757 involved in this incident at the
time the AD was issued in 1991, and had installed the
redesigned system. It was these redesigned fasteners that
failed on flight 1250.

Since the incident on March 22, US Airways reported to the
Safety Board that it had inspected the wing panels on all of
its 757s and found problems with wing panel fasteners on
several other aircraft, which were since repaired and
returned to service.

The Safety Board is continuing to evaluate the design,
installation, inspection and maintenance of the failed
components to determine the cause of the failure and the
impact on the 757 fleet.

The NTSB has also reviewed the data extracted from
aircraft’s flight data recorder (FDR), and in conjunction
with statements from the flight crew, the Safety Board found
that there was no substantial change to the aircraft’s
handling characteristics after the panel separated from the
wing. Because of this, the NTSB has reclassified this event
from an accident to an incident.

NTSB Media Contact: Peter Knudson
(202) 314-6100
[email protected]