As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE AIRCRAFT WAS AT NORMAL CRUISE, THE PILOT STATED THAT IT STARTED TO LOSS POWER AND RAN ROUGH. AFTER LANDING AT A ALTERNATE AIRPORT THE AIRCRAFT STOPPED RUNNING. AFTER PULLING THE CYLINDER, THE TOP OF THE EXHAUST VALVE WAS MISSING. THE STEM AND RETAINING CLIPS WHERE STILL IN PLACE. THE TOP OF THE VALVE HAD BEEN FOUND IN THE INTAKES. CAUSE OF THE MALFUNCTION UNKNOWN. TOTAL TIME ON THE VALVE IS 1146.8 HOURS. (M)