What was found
ON APPROACH INTO PHX EN ROUTE FROM PHL RECEIVED GREEN HYDRAULIC SYSTEM LOW LEVEL INDICATION ON LIGHT PANEL. DECLARED EMERGENCY AND LANDED WITHOUT FURTHER EVENT. MAINTENANCE SERVICED 6 QUARTS IN GREEN HYDRAULIC SYSTEM AND INSPECTED AIRCRAFT FOR EVIDENCE OF HYDRAULIC LEAKS, NO LEAKS WERE NOTED. ON ENGINE START HYDRAULIC FLUID WAS FOUND DRIPPING FROM NR 1 ENGINE DRAIN MAST. INSPECTED NR 1 ENGINE AND DISCOVERED FLUID LEAK AT PRESSURE LINE FITTING THAT CONNECTS TO NR 1 ENGINE DRIVEN HYDRAULIC PUMP. REMOVED AND REPLACED O-RING SEAL AT FITTING OF HYDRAULIC PUMP, RAN ENGINE, LEAK CHECK WAS GOOD.