Uncoordinated flight in cruise

[MarkA]

The experience on my XLS was it was pretty random between left or right rudder being required. Setting the nose wheel tension closer to the max seemed to help somewhat but did not completely solve the problem. Installing the Bret fin fixed the issue completely. I don't know if they are still available but I'd get one to see if that resolves the issue you're seeing.

[waynemcc999]

The experience on my XLS was it was pretty random between left or right rudder being required. Setting the nose wheel tension closer to the max seemed to help somewhat but did not completely solve the problem. Installing the Bret fin fixed the issue completely. I don't know if they are still available but I'd get one to see if that resolves the issue you're seeing.

I also fly an XLS, had the nose corking problem, got some improvement with the nose wheel tension... and most importantly, "Installing the Bret fin fixed the issue completely".
Wayne

[jwx96]

I agree with Soareyes. The plane flys coordinated with the nose wheel fairing removed. It’s also easier to track a localizer or GPS when hand flying an approach if the nose isn’t being pulled to one side or another.

[geekmug]

Yes, the front wheel fairing is notorious for acting like an airfoil and getting sucked to one side, even the forum banner shows the nose gear turn to the left. It doesn't happen every time, so setting the trim tab is unreliable for correcting it. Most folks either take the fairings off or have gotten a Bret fin to correct the issue.

I tried to get a fin from Bret, but he didn't get back to me after giving me a quote. So, I ended up making my own:

My fin is 3D printed out of ASA w/ 10% Glass Fiber. I used slightly long bolts and a rubber foam strip on the mating surface. I went through a number of iterations to refine the shape and ensure the part could handle the potential wind forces, including mounting in a vise and doing a pull tests to destruction. I suspect I could get away with a lower profile fin to achieve the same result, but the cold weather has limited flying.

I have debated offering up the 3D model, but I'm afraid someone would print it with PLA or PETG and it would melt or shatter. I'd be willing to print one and ship it to someone, but I'm also not trying to be a vendor or provide warranty that the print suitable for any purpose. The surface finish of ASA-GF off the printer is never aerospace quality, so it needs to be prepped (drilled/putty/primer/sanding) and painted.

[ZAV]

Thanks for all the input.

I took the nose wheel fairing off and flew today. No difference . No increase in speed (maybe a little slower) and still needed the same amount of left rudder in a cruise configuration.

I guess I’ll just adjust the rudder trim and put the fairing back on and see if that helps my left leg some.

Any other thoughts?

[Rich]

I got to thinking about the flaps, since you say your situation changed. The upper limit of the flaps on the outer portion is determined by the placement/thickness of pad(s) placed in the enclosure for the balance weight. These are just glued in place. Should it/they somehow come unglued and fall off on one side or the other, that flap would retract further than the other side.

There is also a pad glued under the upper wing skin extension. This performs a different purpose, but can fall off.

[ZAV]

I appreciate the thought about the flaps.

I’ve never looked there before so don’t know if there should be a pad or not. I took a couple of pictures. The left one looks like there may have been pads there before.

[ZAV]

Finalizing this post for anyone that searches later:

Adjusting the rudder trim to adjust for the right yaw in cruise flight corrected the issue. I didn’t find any other reason for the right yaw such as the nose wheel “corking”.

[Rich]

I appreciate the thought about the flaps.

I’ve never looked there before so don’t know if there should be a pad or not. I took a couple of pictures. The left one looks like there may have been pads there before.

Those pads serve an additional function. First of all, the flaps are supposed to have a pre-load on them when retracted in flight. Part of that preload is effected by having the balance arm weight press against the bottom of that enclosure*. This is the up-stop. If there is no pad the metal arm/weight will press directly against the composite and could easily wear through. If the arm doesn't contact anything it's not hitting the true up-stop.

* See the AMM section 27-50 > Maintenance Practices > 3. Test the flap control system.

I also published an article on the DPA website on the subject: DA40 Flap Preload When Retracted