Incident Overview
A single-engine airplane experienced a catastrophic engine failure during a cruise climb and subsequently collided with terrain during an emergency landing. The commercial pilot reported hearing and feeling a loud explosion from the engine, followed by observation of numerous punctures in the top of the engine cowling. The engine stopped producing power within 10 seconds of the explosion.
Pilot Report
The pilot elected to land on a gravel road. The airplane touched down at 70 knots and eventually ran off the side of the road due to a sharp left bend. After leaving the road, the airplane impacted low brush and boulders and continued down a hill before coming to rest.
Engine Examination
The engine had undergone its last overhaul on June 16, 2000, and had accumulated approximately 5 hours of operation since then, of which 2 hours were in an engine test cell. Post-accident examination revealed that the two connecting rod bolt nuts for the number 6 rod were found loose in the bottom of the engine case. The nuts were not stripped or damaged.
Probable Cause
No probable cause was stated in the source.