As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ENGINE LOST ABILITY TO GOVERN THE PROPELLER RPM DRIVING THE PROPELLER TO FEATHER. LOSS OF PROPELLER RPM LED TO A NO-POWER SITUATION REQUIRING A NO POWER GLIDING APPROACH BACK TO DEPARTURE AIRFIELD. TROUBLESHOOTING FOUND THE PROBLEM TO BE A ROTATED PROPELLER SLEEVE IN THE NOSE GEARBOX, DEFORMING THE PROPELLER OIL TRANSFER TUBES, AND CUTTING OFF OF OIL PRESSURE TO THE GOVERNOR AND THE PROPELLER. ENGINE IS APPROXIMATELY 10 HOURS SINCE OVERHAUL.