What happened
The pilot reported a loss of oil pressure followed by a complete loss of engine power. During the descent, witnesses observed smoke trailing from the aircraft; one observer noted the smoke as early as nine minutes before the accident. Witnesses further reported seeing the aircraft stall, roll to the right, and descend vertically. The aircraft impacted the terrain in a nose-down pitch attitude and exploded upon impact.
The investigation
A post-accident examination of the engine identified that the number six connecting rod end cap had failed. This failure was caused by oil starvation. The investigation determined that oil starvation was the result of a piston blow-by condition within the number six cylinder. This condition led to crankcase pressurization, which forced oil out through the breather tube. Additionally, the blow-by condition caused the burning of oil in the number six cylinder, which produced the smoke observed by witnesses prior to the crash.