What was found
AFTER TAKING OFF FROM KDOV, NR 1 HYDRAULIC SYSTEM QUANTITY DECREASED RAPIDLY, CREW RAN ABNORMAL CHECKLIST IN ACCORDANCE WITH B-747-200/300 QUICK REFERENCE HANDBOOK. CONTINUED FLIGHT AND LANDED SAFELY AT KJFK. AFTER LANDING MAINTENANCE CREW FOUND A RUPTURED HYDRAULIC FLEXIBLE LINE DOWNSTREAM THE NR 1 HYDRAULIC AIR DRIVEN PUMP. REMOVED AND REPLACED THE RUPTURED LINE WITH A SERVICEABLE ASSEMBLY IN ACCORDANCE WITH BOEING 747 AMM 20-11-18, NO FURTHER LEAK NOTED AT PRESSURE CHECK. AIRCRAFT RESTORED TO NORMAL.