CEN21LA353

The flight instructor reported that, while performing takeoff and landing practice, the airplane touched down normally, then began drifting to the right, and both he and the student pilot attempted to correct without success. The airplane continued off the right side of the runway, and the right main landing gear impacted a runway light and separated from the airplane. The runway light was mounted on a concrete base that protruded from the ground about 1 inch and the stanchion, which was a small pipe, broke at the threads at its base. Based on these observations, the runway light should not have resulted in complete separation of the landing gear. Examination of remnants of three of the eight bolts that secured the landing gear to the wing spar revealed fracture features consistent with overstress. The five remaining bolts were not recovered, and their failure mode could not be determined. The circumstances of the accident were consistent with a loss of directional control due to the failure of the right main landing gear attachment hardware for reasons that could not be determined based on the available information. The airplane manufacturer relayed information regarding landing gear collapses on similar model airplanes, including one landing gear separation, due to fatigue and corrosion of the landing gear mounting hardware. About 7 months after this accident, the manufacturer issued a service bulletin requiring replacement of landing gear attachment hardware on various models, including the accident airplane model.

On August 3, 2021, about 1115 eastern daylight time, a Piper PA-28-181, N728A, was substantially damaged when it was involved in an accident near Jeffersonville, Indiana. The flight instructor and student pilot were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. The flight instructor reported that they were performing takeoff and landing practice and that the accident occurred on the sixth landing of the flight. He noted that the approach and landing were normal, with the airplane touching down on the main landing gear with the engine at idle. The airplane was slightly left of centerline and began drifting toward the right. The student and flight instructor both attempted to correct for the right drift without success, and the airplane continued off the right side of the runway. The right main landing gear impacted a runway light and separated from the airplane. The airplane incurred substantial damage to the right wing and fuselage. Photos of the runway light indicated that the concrete base was about 1 inch above the surrounding ground, and the light stanchion was a small pipe threaded into a flange base. The pipe broke at the threads at the flanged base. Examination of the airplane revealed that the landing gear leg was intact and the bolts and screws securing it to the wing main spar had fractured. The landing gear is attached to the main wing spar by four screws securing it to the top spar cap, and four bolts securing it to the bottom spar cap. Four fragments from three bolts were recovered for examination. The recovered bolt remnants were examined at the NTSB Material Laboratory and exhibited fracture features consistent with overstress. The airplane manufacturer relayed information of several aircraft that had broken or corroded landing gear attachment bolts discovered during maintenance, and one that resulted in separation of the landing gear during landing roll. On March 31, 2022, the manufacturer issued Piper Service Bulletin 1375, requiring replacement of landing gear attachment hardware on select Piper model PA28 and PA32 airplanes.