What was found
(CAN) DURING PRE TAKE-OFF CHECKS FOR THE FIRST FLIGHT OF THE DAY (PARK BRAKE ON), THE FLIGHT CREW NOTICED THAT THE NR 2 HYDRAULIC SYSTEM HAD LOST MOST OF ITS FLUID. AIRCRAFT GROUND RETURN AND DURING THE TAXI BACK TO THE GATE, THE NR 1 HYDRAULIC SYSTEM QUANTITY WAS ALSO OBSERVED TO BE GOING DOWN. MAINTENANCE INSPECTION REVEALED THAT THE LT OB (NR 1) BRAKE HYDRAULIC FLEX HOSE TO BE LEAKING FLUID. A NEW FLEXIBLE BRAKE HOSE ASSEMBLY P/N: DSC252A4-0230 INSTALLED, BOTH HYDRAULIC SYSTEMS SERVICED AND BLEED IAW AMM (TC NR 20060802009).