WASHINGTON (CNN) -- Federal investigators found cracked wing fasteners on a US Airways plane that lost a wing panel over Maryland in March, according to the National Transportation Safety Board.
iReporter and Flight 1250 passenger Paul Shepherd took this photo of the damage through the aircraft's window.
Investigators found cracked wing clips on seven of the airline's 18 older Boeing 757 aircraft, the NTSB said.
All of the aircraft have been repaired, according to the NTSB, which is checking to see if other airlines' fleets could be affected.
But while broadening the scope of its investigation, the NTSB also appeared to play down the seriousness of the March 22 "accident," recharacterizing it as an "incident."
The safety board changed its characterization because, contrary to its earlier belief, evidence shows the missing wing panel did not change the way the airplane was able to fly, it said.
The composite materials panel, measuring 4 feet by 5 feet, broke loose from the upper side of the left wing on US Airways Flight 1250 somewhere over Maryland.
The panel struck several windows towards the rear of the aircraft, causing the outer pane of one window to crack. The inner panel was undamaged, and the plane remained pressurized.
The flight, en route from Orlando, Florida, to Philadelphia, Pennsylvania, landed safely about 30 minutes after the incident. None of the 174 passengers or six crew members were injured.
The wing panel has not been found, but the NTSB said investigators examined the remaining components and found that metal fatigue had caused two of the three clips securing the panel to fail before the March flight, and the remaining clip failed during the incident flight.
The NTSB said the clips involved were installed after faults were found in earlier fasteners.
In the late 1980s, the Federal Aviation Administration ordered operators of 757s to install a redesigned fastening system. At the time, Eastern Airlines, which operated the 757 involved in the incident, installed the redesigned system, the NTSB said. It was these redesigned fasteners that failed on Flight 1250, the safety board said.
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 effect on the 757 fleet. E-mail to a friend