Accident Sequence
During a forced landing following a total loss of engine power in dark night conditions, the airplane struck transmission wires and trees before coming to rest inverted along a fence row.
Engine Examination
Inspection of the engine revealed a hole in the #2 piston. Physical evidence indicated that the exhaust valve had migrated out through the exhaust port. Metal debris found in the oil sump was identified as parts of the #2 exhaust valve seat.
Maintenance History
The engine, serial number 217105R, had been overhauled in March 1992. However, the maintenance records did not indicate that the valves were replaced during that overhaul. According to a manufacturer representative, the guidelines for an engine overhaul require changing the valve. The engine was subsequently removed and reassembled in August 1993 and again in February 1994.