As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FOLLOWING A ROUTINE FLIGHT, A ROUTINE INSPECTION FOUND THAT THE AFT ALTERNATOR BELT GROOVE HAD BROKEN AWAY FROM THE STARTER RING ASSY. THIS HAD CAUSED THE BELT TO BE DAMAGED BEYOND USE. PIECES OF MATERIAL FROM THE STARTER RING AND RUBBER FROM THE BELT WERE FOUND THROUGHOUT THE ENGINE BAY. POSSIBLE CAUSE COULD BE A MFG FLAW OR EXCESSIVE BELT TENSION.