Incident
The aircraft sustained damage during a forced landing on snow-covered terrain. The forced landing was necessitated by an engine failure that occurred while the aircraft was climbing.
Investigation
An investigation into the engine failure revealed that the engine contained 50-weight oil, and the ambient temperature at the time of the incident was approximately 15 degrees Fahrenheit. The engine had been pre-heated from the top because the heating hose could not be inserted through the lower cowl near the oil sump.
Teardown Findings
A subsequent teardown of the engine disclosed that the connecting rod cap bolts for cylinders #3 and #4 had failed. The failure occurred after the rod bearings had frozen due to a lack of lubrication.
Conclusion
The investigation determined that the engine failure was caused by the failure of the #3 and #4 connecting rod cap bolts after the rod bearings had frozen from lack of lubrication.