What was found
WHILE TAXIING OUT TO RUNWAY AT A LOW SPEED, BRAKES FELT LIKE THEY WERE GRABBING AT QUICK INTERVALS. WHILE BACK-TAXIING ON THE RUNWAY, WE TESTED THE BRAKES AT A SLIGHTLY HIGHER SPPED APPROX. 40 KTS AND UPON BRAKING, THEY WERE GRABBING EVEN WORSE. REPLACE THE BRAKE CONTROL UNIT. REMOVED SUSPECTED INOP BRAKE CONTROL UNIT P/N DAP00100-11 S/N 501870826. INSTALLED A TESTED BRAKE CONTROL UNIT P/N DAP00100-11 S/N 288160289. OPS AND LEAK CHECK GOOD IAW EMB-505 AMM CH 32-41-01