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Any suggestions?
My plane was pulling to the right so I tried bending the aileron trim tab up and it helped. So I bent it a little more up and the pulling to the right seems worse! I’m wondering if this is because the tab is attached to the aileron so the tab pushes the aileron down if it’s bent up, perhaps making the force opposite to what I’m trying to achieve. Thought I’d throw this question out to see if someone knows more about this adjustment than me. Thanks.

No direct experience with the "pulling to the right" issue you mention, but I have helped my A&P do the aileron deflection checks in paragraph 06-00-00 of the AMM, and complete the test and adjustment troubleshooting procedures in chapter 27-10. Chapter 57-60 has more aileron maintenance practices that can ultimately affect the balance and trim of the aircraft. Unfortunately the AMM does not say "turn one bolt 1/4 turn and go fly again." For me, going through the aileron adjustment procedures was back in the good ol' days when tinkering was fun and my A&P accepted payment in beer. I'm not sure but perhaps a Diamond Service center may give you a flat rate of what it would cost to do an aileron rehab vice giving them a blank check.

It might be counter-intuitive but there are no words in the AMM that say "bend the trim tab." It only has one statement within the entire AMM that says that "the aileron trim tab can only be adjusted on the ground." Nothing in the AMM is difficult to understand or do - but it is much more involved than bending a trim tab.

Notice that the Aileron Adjustment Procedure detailed in 27-10 involves pulling bolts out of the control rod connections to see exactly how things line up to ensure no binding. There are also bearings in the aileron control rod system that may need replacing. Also, the numerous bushings at the aileron hinge points are something worth considering replacing. Our composite planes don't corrode but those little metal parts that hold it together do corrode. Bushings bind and wear out and the ailerons can get "sloppy" in their movement. I would especially look at those exposed bushings and bolts out on the wing where the weather and dirt/dust will impact movement over time. You can see the condition of those bolts and bushings by just looking closely at them. For the work done on my DA-20, we actually found it easiest to remove the wing - flip it upside down on a padded table and replace those bolts/bushing in a comfortable standing position vice upside down under the wing. Some of those bushing took some encouragement to be removed as they were mostly seized into position. If you go that route I would tackle the Flaps hinge points too as they are likely in the same condition.

Thanks Mark, appreciate the great input. That’s interesting that there is no mention in the manual of what to do with the trim tab.

Normally what you would do is bend the tab in the direction that you want the wing to go. The DA 20 normally has a tab only on the left aileron. If you have a plane turning to the right then you would want more up aileron on the left wing to counteract the turn. Thus you would bend the tab down.

If you bend the tab up then the aileron will want to go down and it would make your wing go up thus rolling to the right.

It may be worth your while to see where your rudder tab is as well. Although it would not have as much influence on your roll action it would still affect if it is bent one way or the other. Also be patient and adjust in small increments.

When you put your stick in the center both ailerons should be aligned with the flaps the same amount. If you check it from behind and look at both ailerons with the flaps up then you can see if there may be a rigging issue.

Paul

You should also check the alignment of your flaps. I had a similar problem but turning to the left. My AMO turned the actuator bolt out half a turn on the left side IIRC and that cured the problem.