As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING TAXI A SQUEEL WAS HEARD FROM THE ENGINE. AFTER SHUTDOWN PILOT OBSERVED THAT PULLY WAS LOOSE ON FRONT ALTERNATOR, 2. THE PULLY HAD BEEN RUBBING ON ALTERNATOR CASE, CAUSING THE NOISE. THE ALTERNATOR BELT WAS REMOVED AND ACFT FLEW BACK VFR TO BASE WITH NR 1 ALTERNATOR. DURING REMOVAL ALL INDICATIONS POINT TOWARD THE NUT ON THE ALTERNATOR SHAFT THAT HOLDS THE PULLY IN PLACE HAD BECOME LOOSE.