What was found
THE NR 7 LEADING EDGE SLAT WOULD NOT RETRACT AFTER TAKEOFF. THE FLAPS WERE CYCLED AND THE LEADING EDGE DEVICE RETRACTION FAILURE CHECKLIST WAS COMPLIED, BUT THE NR 7 SLAT WOULD NOT RETRACT. SOME LOSS OF THE A-SYSTEM HYDRAULIC QUANTITY WAS ALSO OBSERVED. THE AIRCRAFT WAS RETURNED TO EWR WHERE IT LANDED WITHOUT INCIDENT. MAINTENANCE FOUND THE NR 7 LEADING EDGE SLAT ACTUATOR PISTON END CAP BLOWN OFF. THE NR 7 SLAT ACTUATOR WAS REMOVED AND REPLACED. LEAK AND OPERATIONAL CHECKS WERE GOOD.