What was found
THE A-SYSTEM HYDRAULIC QUANTITY WAS LOST APPROXIMATELY 15 MINUTES INTO FLIGHT. THE LOSS WAS ACCOMPANIED BY ILLUMINATION OF THE NR 1 AND NR 2 PUMP LOW PRESSURE LIGHTS. THE LOSS OF HYD SYSTEM-A QTY CHECKLIST WAS COMPLETED AND THE AIRCRAFT WAS RETURNED TO EWR WHERE IT LANDED WITHOUT INCIDENT. MAINTENANCE FOUND A-SYSTEM PRESSURE HYDRAULIC FLEX LINE IN THE LT FLAP WELL INBOARD OF ENGINE PYLON RUPTURED. THE LINE WAS REMOVED AND REPLACED AND LEAK CHECK WAS GOOD.