As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE DOING OVERSPEED GOVERNOR CHECK, ENGINE RPM STAYS ABOVE TAKEOFF, PROP GOVERNOR HIGH, AND WILL NOT REDUCE WHEN POWER LEVER AND CONDITION LEVER ARE RETARDED. THIS CONDITION ALSO PREVENTS THE PROP FROM COMING OFF THE LOCKS. TROUBLE SHOOTING HAS DETERMINED THAT THE INLET SENSOR AND THE PROP GOVERNOR ARE NOT THE CAUSE OF THIS MALFUNCTION ANDTHE FUEL CONTROL IS, INDEED THE PROBLEM. REPLACED FUEL CONTROL, RAN AND ADJUSTED AS REQUIRED.