What was found
SHORTLY AFTER TAKEOFF THE VENTRAL RUD FAIL CAS MESSAGE ILUMINATED. THE MESSAGE CLEARED IT SELF SEVERAL MINUTES LATER AND THEN CYCLED ON AND OFF SEVERAL TIMES OVER THE COURSE OF THE 45 MINUTE FLIGHT AT FL370. WE THEN RECIEVED AN AP FAIL AND YD FAIL CAS ALONG WITH THE VENTRAL RUD FAIL. THE QRH WAS FOLLOWED AND AN EMERGECY WAS DECLAIRED TO EXPIDITE OUR DESCENT. ALL THREE CAS MESSAGES CONTINUED TO CYCLE ON AND OFF UNTIL LANDING. PERFORMED TROUBLESHOOTING AND FOUND THE SERVO INOP. REMOVED AND REPLACED VENTRAL RUDDER SERVO IAW EMB505 AMM 22-11-11/400. UPDATED SOFTWARE IAW IAW EMB505 AMM 22-11-11/200. VERIFIED OPS CHECK GOOD IAW EMB505 AMM 22-11-11/500. VERIFIED RIGGING PIN REMOVED.