What was found
ON HEADING TO JOIN THE FINAL APPROACH COURSE TO 31R AT JFK, SYSTEM 1 LOW LEVEL LIGHT ILLUMINATED. OBSERVED SYSTEM A HYDRAULIC QUANTITY DECREASING RAPIDLY PAST 2 TO LESS THAN 1 GALLON. REQUESTED A VECTOR OFF THE FINAL APPROACH COURSE TO COMPLETE THE SYSTEM A LEAK AND SYSTEM A LOSS CHECKLIST. NOTIFIED ATC OF THE HYDRAULIC LOSS AND RETURN FOR A LANDING AT JFK. EMERGENCY EQUIPMENT WAS PRESENT, CLEARED THE RUNWAY AT THE HIGH SPEED TURNOFF. FOUND LOOSE HYD LINE ON NR 1 ENG HYDRAULIC PUMP. RETORQUED B-NUT. RAN ENG PER MM 29-13-01, NO LKS NOTED. A/C OK FOR SRC.