EMB ERJ 190/195 ER/LR
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Flight Crew Total 10000
Troubleshooting; Confusion; Training / Qualification
Aircraft Equipment Problem Critical
Air Traffic Control Provided Assistance; Flight Crew Landed in Emergency Condition; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Diverted; Flight Crew FLC Overrode Automation
Aircraft
While at FL300 we experienced multiple uncommanded rudder deflections. The first occurred over a waypoint and was very subtle. We were fortunate because due to the first event I maintained positive contact with the flight controls. The second event was more violent and resulted in an undesired aircraft state. By referencing the turn and slip coordinator and our own senses; we knew the aircraft was 'cross controlled'. I pressed and held the quick disconnect button and took control of the aircraft. We immediately [requested priority handling] and requested a diversion to ZZZ. Unfortunately there was no EICAS [Engine Indicating and Crew Alerting System] messages to provide an appropriate course of action. We realized it was a rudder issue so I felt it was wise to slow the aircraft to 250 knots and minimize bank angles to 10 degrees or less while turning the aircraft. There was no apparent incorrect rudder trim and realized that the problem was due to uncommanded rudder deflections. While being vectored for the approach; I transferred controls to the First Officer and referenced the QRC and QRH for any guidance. We found that there was no action to be taken and we elected to land with flaps full. A successful approach and landing was made resulting in no damage to the aircraft or injuries. Upon landing we received a Flight Control No Dispatch EICAS message.
EMB190 Captain reported uncommanded rudder deflection in cruise flight resulting in a diversion.