As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING THE 100/300/600 HOUR INSPECTION AN ANOMALY WAS FOUND ON THE MAIN DRIVESHAFT COUPLING. 1 FLANGE INNER SURFACE APPEARS TO HAVE BEEN TURNED DOWN ON A LATHE SO THAT IT IS APPROXIMATELY 0.050" THINNER THAN THE FLANGE ON THE OPPOSITE END OF THE COUPLING.