uncommanded left roll tendency

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ahmebane
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uncommanded left roll tendency

Post by ahmebane »

My fairly-newly-purchased 2003 DA-40 likes to roll left. I've checked the flight characteristics with flaps down a notch & that does not change the roll, so I dont think the flaps are hanging out in the breeze. The roll is coordinated, in that the ball is centered, but hands-off the plane really wants to roll left.

Other observations: the left aileron trim tab is bent upwards slightly, which would counteract this left roll tendency; the rudder trim tab is bent fairly significantly to the right, which would introduce a left rudder force. So these two are fighting each other.

One other observation, and I have no idea is this is normal or whether something happened to the tail sometime in the past. When the elevator is centered on the right winglet (term?) of the horizontal stabilizer, the left side of the elevator is NOT centered/aligned on the left winglet of the horizontal stab. As I write this, I dont 100% recall which way it is off. Seems like the elevator should be centered across the stab. Could this be introducing some roll tendency? I'll go to the airport tomorrow & check which way its off, but I think the elevator is above the stab, which would introduce a downward force on the left side.

Any thoughts? I' a first time owner - how much of the diagnosis & correction should I turn over to the shop? They are a Diamond-certified facility.
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astaib
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Re: uncommanded left roll tendency

Post by astaib »

Hi,

Mine also has tendency to go left but I bent the tab in order to compensate it.
Now it’s fine but always a bit different when I’m alone or when we are balanced left/right.

My elevator is straight.

Arnaud.
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DA40 Star 180 / 40.026 / 2001
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Steve
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Re: uncommanded left roll tendency

Post by Steve »

On my airplane:

The left aileron trim tab is bent upwards slightly,
The rudder trim tab is bent slightly to the left,
The elevator is level with the horizontal stabilizer fairings on both sides.

I haven't touched these in the 19 years since the airplane arrived from the factory, and it flies straight.

Steve
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Lance Murray
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Re: uncommanded left roll tendency

Post by Lance Murray »

Remember that the tab must be removed to be adjusted. If you bend it while attached you risk damage to the surface it is attached to.
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