What was found
ON THE 29TH OF JUNE 2010, THE ACFT WAS FLYING IN CRUISE, THE PILOT NOTICED THE NR 4 ENGINE OIL PRESSURE DROP TO BELOW 75PSI. THE PILOT SHUTDOWN THE ENGINE IAW QRH. THE ACFT RETURNED TO BASE SAFELY. INVESTIGATING THE SEAL, FOUND OIL LEAK FROM HYD PUMP, GARLOC SEAL ON THE ENGINE REAR ACCESSORY GEAR BOX. THE GARLOC SEAL WAS REPLACED, ENGINE RUN CARRIED OUT, NO LEAKS FOUND, AND THE ACFT RETURNED TO SERVICE.