TC feedback intermitten BCU fault. TC also feedbacktrain radio was unable to receive message from TSC/CC. ECM-10 ~~~~~ 3652-TC feedback intermitten BCU fault. TC also feedback train radio unable to receive message from TSC/CC.  1651 found FC 314 (BCU Fault). Found 1651 ACU AF solenoid v/v air leaking (due to AF v/v 'O'ring dislodged). Replaced ACU unit & function check - OK. 1651 ACU S/N : OLD : 154/190 NEW : 1516/101  Chan GF/Alan 43905