What was found
AT KSAC ON 10-15-2021, AT 15:24 THE CREW TAXIED TO RUNWAY 20, UPON RECEIVING TAKEOFF CLEARANCE THE CREW TAXIED TO RUNWAY 20AND APPLIED POWER WITH THE BRAKES HELD. THE CREW NOTICED THAT THE BRAKES WERE NOT HOLDING WELL. THE CREW ASKED THE TOWER TO CANCEL TAKEOFF CLEARANCE, AND TO TAXI BACK TO THE JET CENTER. BY THE TIME THE AIRCRAFT REACHED THE RAMP THE RIGHT BRAKE WAS NOT WORKING AT ALL. THE AIRCRAFT WAS TOWED BACK TO THE JET CENTER. THE CREW LOOKED AT THE RIGHT BRAKE AND FOUND HYDRAULIC FLUID ON THE BRAKE. THE BRAKE WAS REMOVED BY MAINTENANCE, THE "O" RINGS WERE CHANGED ON THE PISTONS, THE BRAKE WAS RE INSTALLED. DURING BRAKE BLEEDING IT WAS NOTICED THAT THE BRAKE WAS STILL LEAKING, FURTHER INSPECTION FOUND A CRACK IN THE CALIPER FROM THE PISTON BORE TO THE OUTSIDE OF THE HOUSING.