Incident Overview
During the landing roll at a speed of approximately 10 to 15 miles per hour, the right main landing gear failed, causing the airplane to come to a stop on a taxiway. The failure resulted in the separation of the right main landing gear trailing link and wheel assembly from the aircraft. A portion of the upper trailing link and axle assembly remained attached to the main trunnion.
Landing Gear History
At the time of the incident, the landing gear assembly had accumulated 5,228.5 total flight hours and 3,358 total cycles since new. The trailing link and axle assembly was certified for a service life of 44,400 total cycles.
Metallurgical Examination
A metallurgical examination of the right main landing gear trailing link determined that the failure was due to fatigue cracking. This cracking was initiated by an undetected manufacturing defect. The defect originated from electrical arcing, which produced physical craters on the interior surface of the trailing link and locally altered the microstructure of the material.
Manufacturing Defect Details
The craters and the changed microstructure acted as stress concentrators, which, under the influence of cyclic stresses, would initiate fatigue cracks. The defects were covered by cadmium plating and primer paint. The presence of cadmium plating established that the damage had occurred prior to or during the early stages of the plating process during manufacture.