Accident Details
Following a normal approach and landing, the left wing of the fixed-gear aircraft dropped, and the aircraft skidded on its belly-mounted cargo pod. Despite the pilot's attempt to maintain directional control, the aircraft veered off the runway to the left and down an embankment.
Investigation Findings
Investigation revealed that the left main landing gear strut, a tubular spring steel assembly, was broken approximately midway between the wheel assembly and the fuselage attachment. Laboratory metallurgical analysis determined that the strut failed due to multiple fatigue cracks that originated from an extrusion lap on the inside diameter of the strut.
Manufacturing Defect
Further analysis indicated that the extrusion lap was formed during the manufacture of the tubing from which the strut is fabricated. This lap caused a structural discontinuity from which the fatigue cracks initiated, leading to the failure of the strut during the landing roll.