Incident Overview
A local pleasure flight experienced a sudden decrease in engine power accompanied by a puff of smoke observed in the cockpit. The pilot applied full power in an attempt to return to the departure airport but determined that it was not possible to reach the field. Instead, the pilot executed a forced landing into an open, snow-covered field.
Landing Sequence
After touchdown, the aircraft rolled for approximately 125 feet before flipping over onto its back. The landing gear and structure sustained damage during the overturn.
Power Loss Cause
Post-incident examination revealed that the engine power loss was due to a broken connecting rod on the #5 cylinder. Additionally, a nut on the rod end cap had detached, allowing the rod to separate. No other causes were identified.
Conclusion
The forced landing and subsequent overturn were the result of a complete loss of engine power caused by a mechanical failure internal to the engine. The pilot's decision to land in the snow-covered field prevented a worse outcome.