Accident Sequence
About 15 minutes into a cross-country flight, the aircraft's engine quit with a loud bang. The aircraft was over mountainous terrain at the time. The pilot attempted to land in a small pasture. During the landing rollout, the aircraft encountered rough terrain and nosed over.
Investigation Findings
Post-accident investigation determined that the number 2 main bearing had spun, closing off the internal oil passage in the crankshaft and journal. This led to oil starvation, which caused the failure of the number 2 and number 3 connecting rods. The engine had accrued 1,520 hours since its last overhaul, while the manufacturer recommends a time-between-overhaul interval of 1,700 hours.
Maintenance History
Review of the maintenance records established that, 40 hours prior to the accident, a maintenance facility had found a large amount of metal particles in the oil. The facility warned the pilot about excessive internal engine wear and recommended further inspection before flight. However, no corrective action entries were noted in the aircraft's logbook.