As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING ROUTINE MAINTENANCE, IT WAS FOUND THAT ACTIVATION OF THE NR 1 STANDBY HYDRAULIC POWER UNIT CAUSED THE NR 1 ENGINE DRIVEN PUMP TO BE DRIVEN, IN TURN CAUSING THE PROP TO WINDMILL..MAINTENANCE REPLACED THE NR 1 HYDRAULIC PRESSURE MANIFOLD WHICH CONTAINS THE SYSTEM CHECK VALVE, AND THE AIRCRAFT WAS RETURNED TO SERVICE.