What was found
ON TAXI OUT RECEIVED FLASHING LOW BRAKE PRESSURE & ANTI SKID INOPERATIVE ANNUNCIATORS. ABOUT 20 SECONDS LATER, LOST NORMAL BRAKES, BRAKE PEDALS LOST PRESSURE & WENT TO THE FLOOR. HAD TO USE EMERGENCY BRAKE SYS TO STOP ACFT. SHUT DOWN ACFT & HAD TO BE TOWED BACK TO RAMP. TESTED POWER BRAKES SYS & FOUND BRAKE MOTOR RUNS INTERMITTENTLY. TESTED 28V ON SKID CONTROL RELAY & FOUND THE RELAY IS ENGAGED, 28V INPUT ON A1 IS PRESENT, BUT THE MOTOR FAILS VOLTAGE OUTPUT OF 15V. DISCONNECTED THE BRAKE MOTOR & CONNECTED A 28V LOAD TO THE KN003 SKID CONTROL RELAY & FOUND THE VOLTAGE PRESENT ACROSS THE RELAY IS REDUCED TO 15V UNTIL THE RELAY IS TAPPED ON. FLUSHED RT & LT EMERGENCY BRAKE LINES. BLED ANTI SKID BRAKE SYS IAW MM 32-42-00. VERIFIED FLUSH & BRAKE BLEED. REMOVED FAILED RELAY KN003 & REPLACED WITH NEW. OPS CHECKED GOOD. WORK DONE IAW MM 32-42-00.