What was found
1) PRIOR TO TAKEOFF, LOSS OF HYDRAULIC FLUID LEAD TO DECISION TO RETURN TO THE RAMP. DURING TAXI BACK QUANTITY FELL TO EMERGENCY LEVEL AND HYDAULIC SYSTEM AND BRAKE PRESSURES BEGAN DECREASING. STPPED TAXI AND SET BRAKES FOR TOW IN2) FOUND HOLE IN T/R PUMP SUPPLY LINE. REPLACED LINE PER DACO 70 M/M 78-36-2. SERVICED T/R RES. PER DACO 70 M/M 78-36-2 AND MAIN RES. PER DACO M/M 12-30-1. OP AND LEAK CHECKS GOOD.