What was found
WHILE TAXING, BRAKES FELT SPONGY AND THEN BRAKING WAS LOST. HYDRAULIC SYSYTEM SUMED TO BE WORKING AND SHOWING PROPER INDICATIONS. MANAGED TO STEER INTO TAXIWAY TURNED ANTISKID OFF AND BRAKING WAS RESTABILISHED. TAXIED AIRCRAFT BACK TO GATE. BRAKE WAS WORKING PROPERLY WITH ANTISKID SWITCH OFF. DURING INSPECTION OF THE BRAKES FOUND AIR IN ALL FOUR MAINS, BLED BRAKES IAW AMM 32-42-00-02. PERFORMEND TAXI RUN AND APPLIED BRAKES SEVERAL TIMES OPS CHECKED GOOD.