B737-700
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 210
Troubleshooting
Aircraft Equipment Problem Less Severe
Air Traffic Control Provided Assistance; Flight Crew Diverted
Aircraft
Just leveled off at FL 390 and the aircraft had a yoke right trim to approximately 15 degrees to the right. I tried to trim the aircraft to the right with rudder trim and it did not trim. I tried momentary to the left and it did; tried back to the right no rudder trim to right. Control wheel had a right 15 degree right input. We looked in QRH; made sure all CBs were in and they were. Called Dispatch; told them the problem and asked if they could get Maintenance on also. They did. I ask if there was something simple we could check. They repeated the things we did already. Dispatch asked if we felt comfortable to continue to [our destination]; which is over water. No was the answer. Dispatch looked to find us a diversion. Contacted ATC and diverted. Taxied to gate.
B737-700 Captain reported a problem with the rudder trim which eventually resulted in the flight diverting to an enroute field.