What was found
(CAN) IN POSITION ON RUNWAY, RIGHT AFTER SETTING T/O POWER, WE HAD A HYD Y RSVR LOW LEVEL ECAM WARNING. LOW SPEED RTO. ALMOST ALL OF THE YELLOW HYDRAULIC FLUID DRAINED FROM THE RESERVOIR. WE CLEARED THE RUNWAY, PARKED IN THE DE-ICE AREA AND ASKED TO BE TOWED ON TO THE GATE. FOUND A FLEX LINE BURST ON THE NR 2 ENGINE INBD UPPER THRUST REVERSER DOOR ACTUATOR NEW UPPER HEAD SUPPLY HOSE INSTALLED IAW MM 78-31-49 LEAKCHECK C/OUT-NO LEAKS T/R OPS CHECK C/OUT WITH CFDS & WITH ENGINE RUNNING IAW MM 78-31-00-710-040. FAN COWL CLOSING.