Incident Overview
During a local area personal flight, the aircraft experienced a sudden reduction in engine power. The engine RPM dropped from 2,300 to 1,400, accompanied by noticeable vibration. In response, the pilot decided to perform a forced landing.
Forced Landing and Collision
The only suitable landing area in the vicinity was a road. However, this road contained a 40-degree right turn along the landing roll path. As the aircraft navigated the turn, the right wing struck a fence post. The impact caused the aircraft to spin into an adjacent ditch.
Post-Incident Examination
Following the occurrence, an examination of the aircraft's engine was conducted. The investigation revealed a failure of the right forward cylinder valve rocker box exhaust stud. The stud had backed out, preventing the intake valve from operating correctly. This mechanical issue was the direct cause of the power loss and subsequent forced landing.