What was found
THE AIRCRAFT WAS ON APPROACH TO THE AIRPORT. THERE WAS A LOSS OF HYDRAULIC PRESSURE. THE AIRCRAFT LANDED WITHOUT INCIDENT. UPON INVESTIGATION BY MAINTENANCE STAFF THE RT ENGINE DRIVEN HYDRAULIC PUMP O-RING AT THE PRESSURE LINE FITTING HAD BLOWN ALLOWING THE HYDRAULIC FLUID TO LEAK OUT UNDER PRESSURE. THE FAILED O-RING WAS REPLACED WITH A SERVICEABLE O-RING AND THE HYDRAULIC SYSTEM WAS REPLENISHED. THE RT HYDRAULIC PUMP CHECKED SERVICEABLE. THE LT PUMP WAS REPLACED AND THE AIRCRAFT WAS RETURNED TO SERVICE.