Incident Overview
An aircraft experienced an engine failure during flight and was forced to land in a field. The landing resulted in substantial damage to the aircraft.
Engine Examination
A post-crash inspection of the engine revealed that the number three connecting rod had separated from the crankshaft. The separation occurred when the connecting rod bolts failed.
Metallurgical Findings
Metallurgical examination of the bolts determined that they had been subjected to extreme heat. This heat caused softening of the bolt material, which subsequently led to failure under an overstress condition. Additionally, the connecting rod was found to have been overheated in the area of the bearing between the connecting rod and crankshaft, indicating prior failure and overheating of the bearing.