As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE RETURNING TO BASE DURING FLIGHT, N2 RPM DROOPED. PILOT LANDED AIRCRAFT AND REPORTED MALFUNCTION TO THE MECHANIC. UPON INSPECTION OF GOVERNOR AND ATTACHING AIR LINES, THE DRIVE SPLINE RETAINING CAP WAS FOUND DETACHED AND SMALLER SHAFT FOUND PARTIALLY FAILED AND TWISTED.