B737-300
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 451; Flight Crew Type 12000
Distraction; Training / Qualification; Troubleshooting; Workload
Aircraft Equipment Problem Critical
Flight Crew Took Evasive Action; Flight Crew Returned To Departure Airport; General Maintenance Action
Human Factors; Aircraft
We took the aircraft from a previous crew to fly one last leg for the night. They reported no problems with the aircraft. After takeoff; found excessive aileron trim needed to fly the aircraft. It took 15-18 units/degrees of right aileron trim to fly coordinated flight; in all configurations from takeoff to landing. First Officer was flying. Fuel was balanced; thrust was symmetrical; and the ball was centered; and we needed 15-18 units of right aileron trim to fly coordinated flight. We notified Dispatch to inform Maintenance; and Dispatch told us to return to the departure airport. We were exactly half way to the overnight destination; and we turned around and landed; wrote up the aircraft; and took a different one to our scheduled airport. We did not declare an emergency as we had no problems controlling the aircraft. It appeared to be out of rig. We elected not to fly the 'slam dunk' and coordinated with Approach Control to fly a 15 mile final to configure the aircraft slowly for landing. Previous crew should have noticed and reported the excessive trim problem.
A B737-300 Captain reported that after takeoff 15-18 right aileron trim units were need to attain coordinated flight so Maintenance asked the crew to return to the departure airport.