What was found
JFK - AFTER TAKEOFF, NR 4 HYDRAULIC QUANTITY LIGHT ILLUMINATED WITH LOSS OF HYDRAULIC QUANTITY ON GAUGE. FLUID LOSS CONTINUED WITH ADP OPS EDP PLACED IN DEPRESS. FLUID LEVEL STOPPED DECREASE AT 2.9 GALLONS WITH GEAR UP. RETURNED TO JFK, NO FUEL DUMP REQUIRED. WING GEAR EXTENDED BY USE OF ALTERNATE PROCEDURE. FOUND PRESS LINE ADP TO PRESS MODULE BLOWN OUT. REMOVED AND REPLACED LINE, REPLACED FILTERS IN PRESS MODULE AS PRECAUTION, NO EVIDENCE OF CONTAMINATION, PRESS CHECKED OK MM 29-11-00. TEST WING GEAR ALTERNATE EXTENTION ELECTRIC ACTUATOR MM 32-35-01, AIRCRAFT RETURNED TO NORMAL CONFIGURATION. (M)