As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) PILOT NOTED SEVERE VIBRATION WITH NO WARNING. PRIOR TO SHUTDOWN, THE TORQUE WENT TO ZERO. AIRCRAFT RETURNED OK. INSPECTION REVEALED THE PLANETARY PIN P/N 868051-1 WAS CHAFED BY THE PLANETARY GEAR P/N 358268-1 WHICH IN TURN ABNORMALLY LOADED THE SUN GEAR WHICH SUBSEQUENTLY FAILED.