What happened
During the landing rollout, the right main landing gear of the aircraft collapsed. The captain reported that the first officer had completed a normal landing. Upon taking control of the aircraft, the captain experienced a sharp drop to the right, causing the aircraft to skid down the runway accompanied by a continuous warning horn. Despite continued braking efforts, the aircraft came to a stop on the centerline with a significant lean to the right. There were no injuries reported.
The investigation
An examination of the right main landing gear by the NTSB Materials Laboratory revealed that the outer cylinder had fractured through the transition area above the fused section. This fracture was located approximately 19 inches from the upper end of the cylinder. Investigators identified a fracture initiation point located approximately 28 7/8 inches from the lower end of the cylinder, oriented transverse to the gear.
Analysis of the fracture sample uncovered multiple inclusions and intergranular cracks. These inclusions primarily consisted of aluminum and calcium oxides, with some containing small amounts of iron and manganese sulfides. The investigation identified fracture features consistent with overstress separation, characterized by mostly ductile dimple formations and some cleavage-like features.