Says Panels Should Be Inspected For Missing, Cracked Clips

Following a March incident involving a Boeing 757-200 flying for US Airways, on Thursday the National Transportation Safety Board issued three recommendations to address loose, cracked, and incorrectly-fastened wing panels on the type.

As ANN reported, on March 22 a Boeing 757-225 operated by US Airways as flight 1250 experienced an in-flight separation of the left upper wing fixed trailing edge panel during cruise flight at FL270 enroute from Orlando, FL, to Philadelphia, PA. The panel struck several windows toward the middle of the aircraft, cracking the outer pane of one window. The inner failsafe pane was undamaged, and the pressurization of the aircraft was not compromised.

No emergency was declared, and the airplane landed at Philadelphia International Airport about 30 minutes after the separation occurred. None of the 174 passengers or six crewmembers was injured.

To date, the panel has not been recovered. The B757 upper wing fixed trailing edge panel is a rectangular panel approximately four feet by five feet, with approximately half of the forward side of the panel attached to the panel support beam, which is in turn attached to the wing rear spar vertical stiffeners using three support clips and spacers.

The NTSB says if these attachment points fail -- as what appears to have happened to flight 1250 -- air can flow under the panel, causing it to lift off the wing and separate. The National Transportation Safety Board’s investigation of this incident is ongoing; however, examination of the left wing revealed that the three support clips had fatigue cracks, and the mechanic who removed the clips reported that no spacers had been installed. Additionally, the clips were oriented incorrectly.

The NTSB issued the following recommendations to the FAA:

• Require operators of Boeing 757 airplanes to conduct a one-time visual inspection of the upper wing fixed trailing edge panel support beam clips for cracks, proper orientation, and spacers, and to replace cracked clips and reinstall any clips that are improperly oriented or that lack spacers, in accordance with Boeing Service Bulletin 757-57-0027, Revision 2, dated November 14, 1991. (A-08-22)
• Require operators to report any cracked clips found during the one-time inspection, as requested in Safety Recommendation A-08-22, as well as the part number and orientation of the clips relative to the wing rear spar vertical stiffeners and whether spacers were present; then analyze this information to determine if repetitive inspections are required. (A-08-23)
• Require Boeing to issue more explicit instructions and figures that clearly illustrate the correct orientation of the clips and spacers that attach the Boeing 757 panel support beam to the wing rear spar vertical stiffeners. (A-08-24)

FMI: Read The Full Recommendation (.pdf), www.usairways.com