As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING RUN-UP, LEFT ALTERNATOR FAILED AND COULD NOT BE RESET. INSPECTION REVEALED THE DRIVE PULLEY HOUSING HAD SHEARED. SUSPECTED CAUSE IS MATERIAL FAILURE OF THE METAL ITSELF. SUBMITTER RECOMMENDS THAT OTHER OPERATORS INSPECT THE DRIVE PULLEYS OF SIMILAR ALTERNATORS. PART HAS BEEN RETAINED FOR INSPECTION.