With aileron trim in neutral, my plane rolls to the right. In descents close to maximum speed the rolling is so pronounced that sometimes AP displays “<-AIL”. Unlike rudder, aileron trim is not controlled by the AP, so it has to act with constant force on the controls to keep wings level. If I disconnect the AP during descent, I get an untrimmed plane and have to use quite some force on the controls. At low speeds things seem normal. What is the reason for that? Is it normal for single engine planes or is it something I should worry about?
Assuming a right turning propeller the aircraft will normally want to roll left due to torque effect.
Manufacturers will either offset the fin or engine mount to compensate. In a low torque condition this offset may result in a right roll tendency.
Presumably this is a high power to weight SE?
The other SE effects: slipstream, P-effect combine with torque and can be demonstrated. High power yaw and roll left, low power yaw and roll right ( less roll effect). There is also a gyro effect depending on pitch change.
What fixed trim tabs do you have on your aircraft? Out of a fleet of 9 identical aircraft at one place I instruct they can all demonstrate a degree of roll, occasionally after Maint the fixed trim tabs will require adjustment and flight test. Don’t forget secondary effect of yaw is roll so it can be rudder induced as well, and any flap asymmetry can be a cause as well. What you describe needs maint attention I would say.
it sounds more serious than just prop induced roll. Try to have the aerodynamic trimming of the ailerons checked. It may also be caused by the rudder trim, especially if you happen to have aileron rudder interconnect (but also without). If you keep the plane level, the ball must be in the middle.
Prop turns clockwise, so torque and slipstream should act to the left not right. I’ll verify this behavior in the air one more time to be sure of the direction.
loco wrote:
At low speeds things seem normal. What is the reason for that? Is it normal for single engine planes or is it something I should worry about?
For singles, at cruise or high speeds things should be normal and well balanced I would say, including from adverse yaw !
If you keep wing level with no rudder inputs does the ball stay in the middle? then when you centralize the ball with the rudder and let go the ailerons does the aircraft roll? the latter should tell you about aileron trim issues, especially at high speeds (your case probably?), the former is rudder trim issues
I would look closely at the flaps.
Even a 1-2mm difference between them will create all sorts of weird “plane flying crooked” problems.
BTW it is normal on TBs for the flaps to hang a few mm below the upper stop (which is normally a piece of the wing) and the airflow in flight pushes them right up against the stop. But if somebody stepped onto the flap and bent the linkage, it may not make it. OTOH on a TBM there is no reason for people to do that…
yes that is a constant issue. The Beech has a grey strip on part of the upper side of the flap, continuing the one on the wing. Naturally most people think it’s ok to step on it although it is not….
The last aircraft I took (a C152) flew “strangely” in cruise. I realized the ball was not centered.
When I put rudder input, the plane started to turn ! So I had to bank the plane to fly maintain a heading !
Well, I did the whole trip uncoordonated 
Had the same issue with my aircraft, the right wing had a tendency to drop and the aircraft wanted to roll. All control surfaces were checked and found to be out of trim, once they were adjusted the aircraft was very near to perfect.
