The Incident
While cruising at an altitude of 11,500 feet to clear cloud cover, the pilot noticed the engine slowly losing power. Suspecting carburetor icing, he activated the carburetor heat. However, the engine continued to lose power, eventually rendering the pilot unable to maintain altitude. Forced to descend, he executed a landing in an open field.
Landing and Damage
The touchdown was uneventful, but during the landing roll, the aircraft encountered rough terrain. This resulted in substantial damage to the aircraft. No further details about the extent of damage or the aircraft's condition were provided in the report.
Post-Accident Examination
A teardown inspection of the engine revealed a large hole in the top of the crankcase and numerous internal part failures. Several engine components exhibited coloration consistent with heat stress due to lack of lubrication. Despite these findings, an examination of the oil filter, oil filter adapter, propeller governor, push rod seals, oil pressure line, dipstick tube, oil sump quick drain, oil pump, tachometer drive, and oil filler port/cap found no evidence of a pre-existing oil leak.
Cause Determination
Investigators were unable to determine the initiating event that led to the sequence of failures resulting in the catastrophic engine failure. The specific cause of the power loss and subsequent engine destruction remains unknown.