As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOTS NOTICED A VIBTATION IN FLIGHT (APP 25 MIN. INTO FLIGHT). CREW TRIED TO DETERMINE SOURCE OF VIBRATION (RUMBLE). RT GENERATOR WENT OFF LINE, CREW RETURNED TO HOME BASE. REMOVED RT STARTER/GENERATOR AND FOUND THE BEARINGS & SHAFT SHIFTED OUT OF THE STARTER/GEN HOUSING DESTROYING INTERNAL COMPONETS. STARTER/GENERATOR IS BEING SENT TO REPAIR/O/H FACILITY TO DETERMINE CAUSE OF CATISTROPHIC FAILURE.