As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
HYDRAULIC PRESSURE LIGHT ILLUMINATED IN FLIGHT. RETURNED TO BASE. DURING INSPECTION, DETERMINED THE DRIVE BELT HAD DISENGAGED FROM THE HYRAULIC PUMP DRIVE PULLEY. EXAMINATION REVEALED THAT THERE HAD BEEN A LOSS OF INTERFERENCE FIT BETWEEN THE PULLY AND THE PULLEY'S BEARING INNER RACE WHICH ALLOWED THE PULLY TO OPERATE WITHOUT BEARING ACTION. DRIVE PULLY TO BEARING INNER RACE CIRCLIP CAME UNDONE ALLOWING ENOUGH PLAY IN THE ASSY THAT THE PULLEY WOBBLED ENOUGH TO THROW THE BELT. BELT FOUND UNDAMAGED. SERVICEABLE DRIVE PULLEY ASSY WITH PUMP WAS INSTALLED AND RETURNED TO SERVICE.