What was found
DURING AN ATTEMPTED RT TURN DURING TAXI OUT TO THE RUNWAY FOR A TRAINING FLIGHT, THE CREW ADVISED THEY WERE UNABLE TO MAKE THE RT TURN & REQUESTED A RETURN TO THE CARGO RAMP. UPON ARRIVING IN THE CARGO AREA, THE CREW ADVISED AIRCRAFT LOST BRAKING ABILITY & WERE ABLE TO STOP THE ACFT USING BETA & REVERSE. UPON ENG SHUTDOWN THE ACFT MOVED FWD APPROXIMATELY 10 FEET AS THE CREW PULLED THE THROTTLE OUT OF BETA FOR SHUTDOWN WITH FULL BRAKES APPLIED & THE EMERGENCY BRAKE SET. ACFT WAS PUSHED BACK INTO THE TIE DOWN SPOT & SECURED. NO EMERGENCIES WERE DECLARED & NO DAMAGE WAS SUSTAINED TO THE ACFT.