As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTED THAT RT PROPELLER WENT TO COURSE PITCH WITHOUT PILOT INPUT. PILOT FEATHERED PROP AND KEPT ENGINE RUNNING WITH NORMAL INDICATIONS. PILOT EXECUTED 1 ENGINE LANDING. COMPLETED MAINTENANCE RUN UP, EXERCISING PROP IN VARIOUS PITCHES. NO ANOMALLIES NOTED ON GROUND RUN. R & R PROP GOVERNOR WITH AN O/H UNIT AS PRECAUTIONARY MEASURE. COMPLETED GROUND RUN AND TEST FLIGHT. NO ANOMALLIES NOTED ON EITHER.