Date: 201404
Local time of day: 0001-0600
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Light: Daylight
Aircraft: Regional Jet 200 ER/LR (CRJ200)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class E ZZZ
Aircraft component: Rudder Control System
Component problem: Improperly Operated
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; First Officer
Human factors: Workload; Situational Awareness
Anomaly: Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Weather / Turbulence; Inflight Event / Encounter Loss Of Aircraft Control
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Diverted; Flight Crew Landed As Precaution; Flight Crew Regained Aircraft Control; General Declared Emergency
Contributing factors: Aircraft; Human Factors; Weather
Primary problem: Aircraft

Narrative: On takeoff our clearance was initially to 4;000 FT. When cleared for takeoff; the Tower Controller gave us 'Cleared direct.' I was pilot not flying and the Captain was pilot flying. Shortly after takeoff we started our turn direct and I accomplished the After Takeoff Checklist. At this time we started to encounter Light-to-Moderate turbulence. While attempting to roll out of turn; the Captain (pilot flying-hand flying) alerted me to the fact that he was having a serious flight control problem. I could see the aircraft was rolling/yawing to the left and he was using rudder and aileron in attempt to correct. The malfunction quickly continued to worsen and he asked me for help. I retrieved the QRH and realized that the control problem was so immediate and complex in nature that I needed to help him maintain control of the aircraft; with little-to-no time to accomplish QRH tasks. My fear was that if the aircraft rolled any more to the left; we may not be able to recover to normal flight. I noticed that the 'brick' (turn coordinator) was full left at one point. I immediately told pilot flying to apply more left rudder and lower the nose. I advised pilot flying I would attempt to help by adding left rudder trim. As I added left rudder trim and pilot flying lowered the nose; we began to regain control. After watching his struggle with the Rudder; on initial observation; it appeared to me that we were experiencing a Rudder System Jam. By this point we had already regained control of the aircraft with the Rudder Trim deflected to the left; and the checklist calling for us to press the YAW DISC; I asked the Captain if he still wanted me to push it. We both decided that since the plane seemed more controlled at this point; that we were hesitant to disconnect the yaw damper not knowing if it would make the problem worse. The Captain told me he wanted to transfer the controls to me since he had been struggling with the rudder and ailerons for quite some time and needed relief. I had the radios and the controls at this point and we requested from ATC the nearest airport with at least a 5;000 FT runway. They began vectoring us and as they began to descend us; the turbulence over the mountains again began to increase significantly making the yaw motions worse again. I told the Captain I wanted to climb back up to get out of the turbulence. I executed a climb and requested from ATC an airport nearby with light winds. My thought process was that this would hopefully reduce the turbulence and allow us to line up with the runway without having to use much rudder control. The Controller told us that ZZZ had light winds at 4 KTS. We told ATC we now planned to divert to ZZZ. During this time the Captain again went over the QRH checklist for Rudder System Jam and pressed the disconnect button. No checklist seemed to directly fit the situation we were facing. The Captain also advised the flight attendant of the nature of the emergency using TEST items and told her we did not plan to brace the cabin. He then got the weather and landing data and advised the company of emergency via ACARS. On descent into ZZZ we requested shallow turns to final; as I noticed the turns seemed to worsen the problem. At this point; the rudder pedals seemed much more 'loose' and not as responsive as usual. Even light turbulence in the descent seemed to cause a slight yaw motion. In order to maintain coordinated flight (brick centered); we still required left rudder trim at about half deflection for the remainder of the flight until landing. After landing we had the ARFF trucks follow us to the gate and inspect the aircraft. I believe ARFF said the rudder appeared to be slightly off center; although this could have been due to us still having rudder trim correction in. We deboarded the passengers at the gate. Maintenance arrived at the aircraft and pulled the FDR and CVR circuit breakers. I recalled a video shown in our ground school that showed lowering the nose could help reduce the yaw when in an uncommanded yaw situation. I found this most useful in this situation. I also remembered from my previous training that using trim on a failed flight control; could sometimes help regain some control.

Callback: The reporter states that the DFDR indicates that the Captain was cross controlling the aircraft for unknown reasons.



Synopsis: CRJ-200 First Officer describes a near loss of control incident shortly after takeoff with the Captain flying in moderate turbulence. A rudder anomaly was thought to be the issue and a large amount of left rudder trim was required to bring the aircraft back to stable flight.