What happened
While climbing to an assigned altitude, the pilot was in contact with air traffic control when the engine lost power. The pilot attempted to restart the engine but was unsuccessful, subsequently notifying the controller of the loss of power. The pilot then initiated a forced landing into a field.
During the landing roll-out, the aircraft collided with upslope terraces. This impact caused the aircraft to rotate 30 degrees to the left, which resulted in the separation of the left wing.
The investigation
The engine was removed and subjected to examination. Upon disassembly, investigators found that the No. 5 main bearing journal and the bearing shells were severely worn and gouged.
Analysis by the NTSB Materials laboratory showed that the journal surface was circumferentially gouged across its entire width, accompanied by heat tinting on the journal and adjacent surfaces. Macro etching of a rough ground cross section through the crankshaft revealed lighter etching regions near the journal surface, which were consistent with overheating of the journal surface.