As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THIS ALTERNATOR, O/H WAS INSTALLED. TEST RUN-UP SHOWED NORMAL OPERATION. CHARGING SYS PROBLEMS WERE ENCOUNTERED AGAIN ON THE NEXT FLIGHT. UPON LANDING IT WAS DISCOVERED THAT THE HEX NUT ON THE ROTOR SHAFT WAS MISSING, INDICATING IMPROPER TORQUE AT UNIT O/H. BOTH THE FAN PULLEY AND ROTOR SHAFT WERE FOUND TO BE UNSERVICEABLE.