What was found
(CAN) DURING TAXI ,THE ECAM MESSAGE AILERON BLUE SYSTEM JAM CAME ON UPON THE FLIGHT CONTROL CHECK BY THE FLIGHT CREW. PROCEDURE PERFORMED AS PER CHECK LIST AND THE AIRCRAFT RETURNED TO THE GATE DUE TO HARD DEFLECTION OF CONTROL WHEEL AND UNABLE TO DETERMINE MOVEMENT OF RT AILERON. TROUBLE SHOOTING CONFIRMED THE RT AILERON SERVO AT FAULT. SERVO ASSY WAS REPLACED AND THE AIRCRAFT RETURNED TO SERVICE WITH NO FURTHER INCIDENT. UNIT ROUTED TO THE VENDOR FOR STRIP REPORT.