As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FORWARD COUPLING ON MAIN DRIVESHAFT WAS LEAKING GREASE. UPON TEAR-DOWN INSPECTION, THE SPRING WAS FOUND BROKEN INTO MANY PIECES. THE SPRING WAS MOVING AROUND IN THE COUPLING WHICH CAUSED GOUGES ON THE CAP AND GEAR. REPLACED CAP GEAR AND SPRING. RETURNED TO SERVICE. (X)