What was found
ON FLIGHT 3686 - CREW REPORTED AUTOPILOT DISENGAGED WITH RUDDER 1-2 INOP EICAS MESSAGE.AFTER A FEW SECONDS, THE MESSAGE DISAPPEARED. THE CREW RE-ENGAGED THE AUTOPILOT AND THE MESSAGE RETURNED. THE CREW FOLLOWED THE PROCEDURE IN THE AOM AND THE RUDDER SYSTEM 2 WAS TURNED OFF. THE DECISION WAS MADE TO DECLARE AN EMERGENCY. THE FLIGHT CONTINUED WITHOUT FURTHER INCIDENT AND LANDED SAFELY. AIRCRAFT REMOVED FROM SERVICE. PRESSURIZE HYDRAULIC SYSTEM IAW EMB-145 AMM 29-10-00. NO RUDDER SYS EICAS MSG SHOWN, FOLLOWED FIM 27-23-00-810-802 A, CONNECTED PITO/STATIC SYS TEST TO SIMULATE AIR SPEED TO 140 KNOTS IAW EMB-145 AMM 34-13-00 RUDDER SYS 2 INOP EICAS MESSAGE NOT SHOWN ON EICAS, CAN NOT DUPLICATE AT THIS TIME, AIRCRAFT RETURNED TO SERVICE.