As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING POST-FLIGHT INSPECTION, PILOT FOUND 1 INCH CRACKS EMANATING FROM RIVETS THAT ATTACH BALANCE WEIGHTS TO INTERIOR TO DRIVESHAFT. SUBMITTER RECOMMENDS THIS AREA BE DYE-PENETRANT INSPECTED DURING 1800 HR INSPECTION OF DRIVESHAFT. SHAFT INSTALLED ON TURBINE CONVERTED AIRCRAFT. (STC S4178WE).