2556 encountered Brake Fault during trai ~~~~~ 2556 Brake Fault during train prep.     #2556 FC 308/330/331 Check ACU no abnormalities.But air leak from exhaust.Isolated BC1,PBIC air leak stop.Proceed change out B13 (Double check v/v)No air leak from exhaust after c/o B13.Brake cycle test ok.BCP within criteria.Depot shunting ok.No reoccurance of BCU fault. Done by Saini/Asruddin. 10/09/21