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. INVESTIGATION BY MAINTENANCE DISCOVERED THE FIELD WAS OPEN ON ALTERNATOR. DURING REPLACEMENT IT WAS NOTED THE COOLING FAN AREA WAS COVERED WITH A DUSTING OF BRASS, COPPER COLORED PARTICLES, WHICH COULD BE FROM THE BRUSH SLIP RINGS. ALTERNATOR WAS COVERED UNDER WARRANTY, SO FURTHER DISASSEMBLY AND INVESTIGATION WAS NOT DONE.