What was found
AFTER ROTATION, THE YAW DAMPER WOULD NOT ENGAGE AND WHEN WE TURNED LT, THE LT RUDDER PEDAL WOULD NOT MOVE. AFTER ENGAGING AND DISENGAGING THE YAW DAMPER THE RUDDER OPERATED NORMALLY. ON THE GROUND WE COULD FEEL AND HEAR GRINDING SOUND IN THE RUDDER PEDALS WHILE TAXIING. [SUP 05-03-07] REMOVED AND REPLACED THE AUTOPILOT CONTROLLER IAW THE CESSNA 560XL MAINTENANCE MANUAL 22-11-03. OPS CHECK OF THE AUTOPILOT CONTROLLER GOOD IAW THE HONEYWELL PRIMUS 1000 INTEGRATED AVIONICS SYSTEM TEST AND FAULT ISOLATION MANUAL FOR THE EXCEL.