A CE560XLS returned to the departure airport after takeoff because significant right rudder input was needed at 200 kts as the result of a Rudder Bias Actuator fault.

Narrative

We were assigned this aircraft for a recovery flight. We reported well before sunrise for the ferry flight; preflighted and prepared the aircraft in accordance to SOP and FOM guidance. We then started the engines and taxied to Runway 33 completing all taxi checks and before checks including the rudder bias system check. The Captain was the pilot flying and did not report any anomalies during the taxi out or rudder bias check. Immediately after takeoff the Captain informed me that he was having to apply an unusual amount of right rudder in order to maintain coordinated flight. We had flown this aircraft on four previous legs and it had consistently required a small amount of left rudder trim for coordinated flight. As we continued on the departure and increased airspeed to 200kts he eventually required full right rudder trim for coordinated flight. We both agreed that we should not continue the flight and that we should return to the departure airport. I notified ATC of our situation and they began to give us vectors back to the airport. As the Captain reduced power to descend he observed that the aircraft required less rudder trim to maintain coordinated flight. The return was uneventful. The Captain made an excellent landing and there were no control anomalies during the taxi back to the ramp. After shutdown the Captain immediately contacted the dispatch to inform them that we had returned to the departure airport and then contacted maintenance and described the abnormality.