As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING ROUTINE MAINTENANCE, A METALLIC CLUNK WAS DETECTED WHILE ROCKING THE PROPELLER. FURTHER INVESTIATION REQUIRED REMOVAL OF THE ALTERNATOR. NOISE DID NOT EXIT WITH ALTERNATOR REMOVED. VISUAL INSPECTION OF THE RING GEAR ON THE CRANKSHAFT SHOWED IRREGULAR WEAR PATTERN. BACKLASH CHECK OF GEAR SHOWED .038 INCH BACKLASH. TCM MAXIMUM SERVICEABLE LIMIT, 15.012 INCH.