Accident Summary
The pilot reported a loss of oil pressure followed by a total loss of engine power. Numerous witnesses observed smoke trailing from the airplane, with one witness noting the smoke up to nine minutes before the accident. Some witnesses saw the airplane stall, roll to the right, and descend vertically. The airplane exploded upon impact with the terrain.
Engine Examination
Post-accident examination revealed that the number six connecting rod end cap had failed due to oil starvation. The oil starvation was traced to a piston blow-by condition that formed in the number six cylinder. This blow-by condition led to crankcase pressurization and the loss of oil 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. The underlying cause of the blow-by condition was not determined.
Sequence of Events
According to the pilot, the engine lost oil pressure, resulting in a subsequent loss of power. The airplane then stalled, and witnesses described the aircraft rolling to the right before descending vertically. The impact with terrain was followed by an explosion.