What was found
(CAN) AC WAS ORBITING OVER FIRE. A LOUD SURGING SOUND WAS HEARD. A CHECK OF HYDRAULIC RESERVOIR INDICATED THAT NO HYDRAULIC FLUID WAS REMAINING. FLAPS WERE SELECTED FROM 15 TO 0 DEGREES. HYD BYPASS WAS SELECTED UP. RETARDANT LOAD WAS JETTISONED. AC RETURNED TO BASE. FLAPS WERE SELECTED TO 15 DEGREES, GEAR WAS SELECTED DOWN. UPON LANDING A VIOLENT NOSE WHEEL SHIMMY WAS EXPERIENCED. EMERGENCY AIR BRAKE SYS WAS USED TO BRING AC TO A STOP. NO DC PUMP PRESSURE WAS AVAILABLE DUE TO FLUID LOSS. AC STOPPED SAFELY. UPON INVESTIGATION BY THE MAINT, MAIN HYDR PRESS LINE WAS FOUND BURST CAUSING FLUID LOSS. LINE WAS REPLACED WITH A SERVICEABLE COMPONENT. AC SYSTEM WAS LEAK CHECKED AND THE AC WAS RETURNED TO SERVICE.