What was found
DURING TAXI FOR TAKEOFF, THE CREW LOST ALL HYDRAULIC NR 1, THEREBY CAUSING NORMAL BRAKING TO BE INOPERATIVE. THE AIRCRAFT RETURNED TO GATE USING EMERGENCY BRAKES AND REVERSE (PROPELLER) THRUST. UPON ARRIVAL, A FLUID LEAK MIDWAY UNDER THE RT WING WAS NOTICED. MAINTENANCE WAS ADVISED AND A CREW SENT ON AN AOG TRIP TO THE STATION. FURTHER INVESTIGATION REVEALED THAT THE RT INBOARD SPOILER ACTUATOR CASING HAD RUPTURED AND CAUSED THE LEAK. THE ACTUATOR WAS REPLACED, LEAK CHECKED AND TESTED SERVICEABLE.