What happened
The aircraft had been tentatively sold to two passengers and was being flown from Marlboro, MA to Dumas, AR with a refueling stop at Clarksburg, WV. Shortly after taking off from Clarksburg, a radio problem was encountered. The pilot was cleared to land on Runway 21 (via green light from the tower). Reportedly, the landing touchdown was normal, but during the roll-out, the left gear collapsed and the aircraft sustained minor damage.
The investigation
An examination of the aircraft revealed that the main attaching bolt, located in the gear box, under the fuselage, had failed. Subsequently, the left main landing gear had failed aft and the tire and had separated from the left wheel. A metallurgical examination of the failed bolt, revealed indications of corroded intergranular fracture mode in a crescent shaped area. The remaining portion of the fracture had clean ductile dimples, typical of overstress.