Incident Overview
An aircraft experienced a mechanical failure while en route at an altitude of 10,000 feet MSL. The #3 cylinder, along with its piston and connecting rod, separated from the engine and departed through the cowling.
Pilot Actions
The pilot reported that oil rapidly exited the engine following the separation. Despite this, he was able to maintain partial power for approximately 12 minutes. During that time, he located a semi-circled area suitable for an emergency landing.
Landing and Gear Collapse
During the landing, the aircraft struck a stump and a log, causing the nose landing gear and left main landing gear to collapse.
Investigation Findings
The separated piston, rod, and cylinder were not recovered, so the precise sequence of events leading to the failure could not be verified. Examination of the remaining components revealed that one rod end cap bolt was still in place but its associated nut was missing. The other bolt had failed due to tensile overload. The engine had accumulated 1,107 hours since its last major overhaul.