As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE CHANGING RT PROPELLER GEARBOX, WHEN REINSTALLING BOLTS WOULD NOT GO BACK INTO DRIVESHAFT HOLES. WHEN MANUFACTURER (ZEPPELIN) WAS CONTACTED THEY WERE AWARE OF A MANUFACTURING DEFECT WITH CERTAIN SERIAL NUMBER DRIVESHAFTS. THIS DRIVESHAFT WAS ONE OF THOSE SERIAL NUMBERS THAT THEY IDENTIFIED AS HAVING AN ISSUE. ON INITIAL INSTALL THE BOLT HEAD SMASHED MATERIAL DOWN IN THE HOLES OF THE DRIVESHAFT BOLTS, MAKING THE BOLTS HARD TO REMOVE & TOO HARD, WITHOUT CONCERN, TO INSTALL.