What was found
MLG BRAKE PRESSURE: UPON TAXI OUT I APPLIED BRAKE PRESSURE TO MAKE THE INITIAL TURN OUT OF ATLANTIC AVIATION. I NOTICED THE BRAKES IMMEDIATELY FELT "MUSHY" AND CHATTERED MAKING THE WHOLE COCKPIT SHAKE. I HANDED THE CONTROLS OVER TO MY CO-PILOT AND THE SAME SCENARIO PLAYED OUT FOR HIM . CORRECTIVE ACTION: NETJETS REQUESTED WE REPLACE THE BCU. REMOVED AND REPLACED BCU WITH AN INSPECTED/TESTED UNIT. OPS CHECKS GOOD AT THIS TIME. WORK DONE REF PHENOM 300 AMM 32-41-01. BCU OFF P/N DAP00100-11 S/N 501630626 BCU ON P/N DAP00100-11 S/N 501820714