As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT LOST ELECTRICAL POWER. FOUND RT ENGINE ALTERNATOR BELT NOT ON THE PULLEY SYSTEM. REINSTALLED AND CORRECTLY TENSIONED ALTERNATOR BELT, OPS CHECK OF ELECTRICAL SYSTEM GOOD. PROBABLE CAUSE IS IDLER PULLEY BECAME LOOSE ALLOWING THE ALTERNATOR BELT TO JUMP OFF OF PULLEY SYSTEM. RECOMMEND THAT ALTERNATOR BELT TENSION BE CHECKED AT ALL SCHEDULED MAINTENANCE OF ENGINE. (AL01200404502)