Incident Description
The pilot reported that during cruise flight, the airplane began to vibrate, followed by a loud "bang" and a complete loss of engine power. He attempted to restart the engine, trimmed the airplane for best glide speed, and searched for a suitable emergency landing site. The touchdown was normal, but during the landing rollout, the nose landing gear collapsed, causing the airplane to come to rest inverted.
Engine Inspection Findings
A thorough inspection of the engine revealed that the number 3 cylinder connecting rod had broken at the crankshaft journal. Cracks were observed in multiple locations on the right side of the engine case. Various engine pieces were found in the oil sump, oil pump housing, and oil filter element. The number 3 connecting rod, piston, and cylinder exhibited thermal discoloration, appearing black. A complete teardown of the engine showed that the crankshaft at the number 3 journal area had signs of thermal discoloration and distortion. The other connecting rods and main bearings appeared adequately lubricated. No discrepancies were noted in the oil system.
Maintenance History
A review of the engine logbooks indicated that routine maintenance had been performed, including 50-hour oil changes and servicing.