Narrative:

During initial climb out the aircraft was noticeably flying out of trim. The captain hand flew the aircraft up to 18000 feet. At that time autopilot #1 was selected on. We expected the autopilot to trim the rudder to achieve coordinated flight. The autopilot did not trim the rudder and in order to maintain heading the ailerons were significantly out of a streamlined position. The autopilot was then turned off and the plane immediately banked left until the captain manually corrected the roll. The controls were turned over to the first officer at this point. Autopilot #2 was selected on to see if it would properly trim the rudder. It did not trim the rudder and we again turned the autopilot off. Now manually flying the plane; we trimmed the rudder manually to about 1.4 units of left rudder trim. The plane was now flying coordinated and autopilot #1 was selected on. The autopilot then gradually trimmed the rudder up to 4 units of left trim maintaining coordinated flight. After calling maintenance and crew discussions; it was decided to return to ZZZ to have maintenance check out the rudder system. The crew informed ATC that we wanted to return and descend so as to burn off as much fuel as possible and not land overweight. The remainder of the flight back to ZZZ was uneventful. Because of local weather our arrival and approach was shorter than expected and we landed approximately 2500 pounds overweight. Maintenance was fully debriefed and the plane was taken out of service.

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Original NASA ASRS Text

Title: A319 Captain reported that the Autopilot was unable to trim the aircraft.

Narrative: During initial climb out the aircraft was noticeably flying out of trim. The captain hand flew the aircraft up to 18000 feet. At that time autopilot #1 was selected on. We expected the autopilot to trim the rudder to achieve coordinated flight. The autopilot did not trim the rudder and in order to maintain heading the ailerons were significantly out of a streamlined position. The autopilot was then turned off and the plane immediately banked left until the captain manually corrected the roll. The controls were turned over to the first officer at this point. Autopilot #2 was selected on to see if it would properly trim the rudder. It did not trim the rudder and we again turned the autopilot off. Now manually flying the plane; we trimmed the rudder manually to about 1.4 units of left rudder trim. The plane was now flying coordinated and autopilot #1 was selected on. The autopilot then gradually trimmed the rudder up to 4 units of left trim maintaining coordinated flight. After calling maintenance and crew discussions; it was decided to return to ZZZ to have maintenance check out the rudder system. The crew informed ATC that we wanted to return and descend so as to burn off as much fuel as possible and not land overweight. The remainder of the flight back to ZZZ was uneventful. Because of local weather our arrival and approach was shorter than expected and we landed approximately 2500 pounds overweight. Maintenance was fully debriefed and the plane was taken out of service.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.