What was found
WHILE AT THE DEICE PAD, THE NR1 BRAKE FLEX LINE RUPTURED. SINCE THE PARKING BRAKE WAS ON, THE NR 2 HYD SYS FLUID WAS LOST. THE "HYD", STEERING AND SPOILER CAUTIONS LIGHTS CAME ON AND THE NR 2 HYD QTY WAS NOTED AT ZERO. ACFT TAXIED BACK TO GATE, DURING THE TAXI THE NORMAL BRAKES WERE USED WHICH DEPLETED THE NR 1 HYD SYS QTY DUE TO THE SAME BRAKE LINE RUPTURE. THE NR1 BRAKE FLEX LINE WAS REPLACED, THE HYD SYS WERE SERVICED AND THE ACFT RETURNED TO SERVICE.