As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING A TRAINING FLIGHT, IT WAS NOTED THE NR 2 ALTERNATOR WAS NOT FUNCTIONING. TROUBLESHOOTING BY MAINTENANCE DISCOVERED THE NUT FOR THE STATOR TERMINAL WAS MISSING AND THIS ALLOWED THE BOLT TO MIGRATE INTO THE CORE OF ALTERNATOR WHERE IT WAS CHEWED UP BY THE ROTOR ASSY CAUSING DAMAGE TO THE ROTOR AND STATOR COILS, ALTERNATOR,.