In-flight separation of B-757 wing panel

Citation

(2008), "In-flight separation of B-757 wing panel", Aircraft Engineering and Aerospace Technology, Vol. 80 No. 5. https://doi.org/10.1108/aeat.2008.12780eab.020

In-flight separation of B-757 wing panel

Article Type: Safety topics and notes From: Aircraft Engineering and Aerospace Technology: An International Journal, Volume 80, Issue 5

The National Transportation Safety Board is investigating an aircraft accident in which a panel from the wing of a US Airways B-757, flight 1250 en route from Orlando, Florida, to Philadelphia, Pennsylvania, separated from the aircraft somewhere over Maryland. The aircraft landed in Philadelphia about 30 min after the separation occurred. None of the 174 passengers or 6 crew were injured.

On Saturday, 22 March 2008, at about 9:30 a.m. EDT, a composite panel, measuring about 4 × 5 ft, on the trailing edge of the upper side of the left wing, broke lose from the aircraft and struck several of the windows towards the rear of the aircraft. The impact caused the outer pane of one window to crack. The inner pane was undamaged and the pressurisation of the aircraft was not compromised.

Because the loss of the wing panel adversely affected the flight characteristics of the aircraft, the event has been classified as an accident.

The wing panel has not yet been located. Safety Board investigators are using a specialised computer program to perform a Ballistic Trajectory Analysis with data such as the aircraft ground track, speed, prevailing winds and other factors to create a search area where the missing panel is most likely to be found. Once a specific search area has been created, local authorities in the vicinity will be notified that an aircraft part may be located in their jurisdiction.

The cockpit voice recorder and flight data recorder (FDR) have arrived at the NTSB’s laboratory in Washington, DC, where the content of each is being evaluated.

Parties to the investigation are the Federal Aviation Administration (FAA), Boeing Commercial Aeroplanes, US Airways, and the Air Line Pilots Association.

Continuing investigation of US Airways flight 1250 on 22 March 2008, the National Transportation Safety Board has developed the following factual information.

Although the separated wing panel has still 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 FAA issued an Airworthiness Directive (AD) requiring operators of 757 s 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 22 March US Airways reported to the Safety Board that it had inspected the wing panels on all of its 757 s 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 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.