As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PROPELLER FEATHERING AT HIGH RPM''S. OIL TRANSFER COLLAR WAS SCORED CAUSING INSUFFICIENT OIL PRESSURE BETWEEN COLLAR AND CRANKSHAFT PILOT SHAFT. RECOMMEND DESIGN CHANGE ON TRANSFER COLLAR, OR CRANKCASE MODIFICATION TO ALLOW REPLACEMENT OF LEFT HALF OF COLLAR INSTEAD OF ENGINE DISASSEMBLY. (X)