"Sticky" Ailerons

"Sticky" might be a bit strong a word but I don't know how else to describe it. I'm rigging my controls out at the hangar. In one direction, when the ailerons are brought to the stops, I feel the controls get slightly tight. It's not hard to overcome and my tech counselor says its nothing to worry about especially since the air loads will easily over come it. Plus like I said, they get only slightly tighter. They are easy to over come.

I've spend hours working the bushings to make them work properly and they all do. I've checked to see if the push rods out to the ailerons rub on the spar. One was actually on one side but no more.

I've disconnected each aileron from the bellcrank and it goes away. So that tells me that it's at the bellcranks. Could this just be the mechanical advantage going to a minimum at the extremes? Is this something to worry about and is my DAR going to ding me for it?

Honestly, I don't feel that it's a safety of flight issue. I've felt a few trainers that didn't have smooth controls throughout the range and I bet my controls are 100% smoother than most trainers but it still bugs the heck out of me.

What have you all found out with your planes?

Check to make sure neither of your bellcranks is going over center (or close). That sounds like a possibility. It *could* result in something bad happening.

Mine were rubbing on the rear spar opening when fully deflected. You might check the clearance around the rod end.

When you get to the point where you feel the drag check and see if you can still twist/rotate the push-pull tube freely. If not, You may have the rodends clocked so they bind up towards the end of the travel by rubbing on the bellcrank.

ArVeeNiner said:

"Sticky" might be a bit strong a word but I don't know how else to describe it. I'm rigging my controls out at the hangar. In one direction, when the ailerons are brought to the stops, I feel the controls get slightly tight. It's not hard to overcome and my tech counselor says its nothing to worry about especially since the air loads will easily over come it. Plus like I said, they get only slightly tighter. They are easy to over come.

I've spend hours working the bushings to make them work properly and they all do. I've checked to see if the push rods out to the ailerons rub on the spar. One was actually on one side but no more.

I've disconnected each aileron from the bellcrank and it goes away. So that tells me that it's at the bellcranks. Could this just be the mechanical advantage going to a minimum at the extremes? Is this something to worry about and is my DAR going to ding me for it?

Honestly, I don't feel that it's a safety of flight issue. I've felt a few trainers that didn't have smooth controls throughout the range and I bet my controls are 100% smoother than most trainers but it still bugs the heck out of me.

What have you all found out with your planes?

Click to expand...

Ugh. I'm chasing the same thing, Kelly. Going to go through the brass bushings on the various pivots next, with something seriously slippery. No mechanical interference or rubbing or over-center anywhere.

I am right behind you!

Are your seat cushions in? Or, have you, by any chance, already installed your aileron trim springs? Either of these will make the last inch or so of aileron travel feel a bit stiff.

curtis said:

When you get to the point where you feel the drag check and see if you can still twist/rotate the push-pull tube freely. If not, You may have the rodends clocked so they bind up towards the end of the travel by rubbing on the bellcrank.

Click to expand...

Curtis is right on here, with the ailerons fully deflected, make sure you still have some "play" twisting the main aileron torque tubes.

Walt said:

Curtis is right on here, with the ailerons fully deflected, make sure you still have some "play" twisting the main aileron torque tubes.

Click to expand...

I'll check that the next time I'm out at the hangar. This is something that I didn't consider or look at.

BTW, there are no seats or springs.

I checked and rechecked clearance between the aileron push rods and the spar, they clear. With the large tubes that run from the sticks to the bellcranks disconnected, the ailerons to bellcrank runs have no stickiness.

I doesnt look like there are over center issues. Im going to take some measurements between some points at full deflection to see if there are any differences between bellcranks.

Thanks for the tips!

Lars said:

Ugh. I'm chasing the same thing, Kelly. Going to go through the brass bushings on the various pivots next, with something seriously slippery. No mechanical interference or rubbing or over-center anywhere.

I am right behind you!

Click to expand...

Hi Lars

Go through each of those bearings. Going into the weekend I thought I was close enough with the bearings. The aileron issue has been kind of a blessing in disguise. It caused me (actually a good friend of mine) to disassemble each bearing assembly. We worked the heck out of them. I was amazed how well we got them working. That is what is so frustrating. After many hours of work, everything works like butta...except for the very last bit of deflection on one side.

Walt said:

Curtis is right on here, with the ailerons fully deflected, make sure you still have some "play" twisting the main aileron torque tubes.

Click to expand...

You have to go a bit further than that...
You need to confirm that you still have play in the push/pull tube rod ends when moving the stick through the full range of elevator travel while also selecting full aileron travel (it is this movement that is actually using most of the available rotation range of the rod ends). Actually, it is sometimes not possible (because of variations in travel range, etc). In this case you adjust for it being just short of binding at full up elevator. This will give you the most possible free travel range (the last little bit of full down elevator would never be used in flight while also using full aileron input)

This has a name

curtis said:

When you get to the point where you feel the drag check and see if you can still twist/rotate the push-pull tube freely. If not, You may have the rodends clocked so they bind up towards the end of the travel by rubbing on the bellcrank.

Click to expand...

I picked this up while working on DC-6's. It's in the manual as "check twizzle of rod ends after installation of control and adjust as necessary prior to locking nut for rod ends" I'm adding a lot of words to make it clear, actually it read something like "...check twizzle"

ArVeeNiner said:

With the large tubes that run from the sticks to the bellcranks disconnected, the ailerons to bellcrank runs have no stickiness.

Click to expand...

Question....where do you disconnect them, at the outboard end of the big tubes?

Second question....are the aileron stops installed and is the measured surface deflection within spec?

...and my tech counselor says its nothing to worry about especially since the air loads will easily over come it.

Click to expand...

No form of control binding is acceptable.

Rivet drag on aileron attach bracket...

Check to see if you have a very small bit of contact near full deflection on your aileron attach brackets from a rivet...

DanH said:

Question....where do you disconnect them, at the outboard end of the big tubes?

Second question....are the aileron stops installed and is the measured surface deflection within spec?



No form of control binding is acceptable.

Click to expand...

1-I disconnected at the outboard end.

2-Stops are installed and deflection is within spec.

I just got off the phone with Van's. They said if there is an issue with the heim joint touching the weldment it's most likely at the control stick end. They said there are very small washers that are added between the joint and the weldment to alleviate this issue. I remember installing these washers because they are such a pain but I will double check anyway.

He was also saying that if this is an issue he's know people that had to relieve the weldment a bit to clear the joint.

I won't be able to get out there until Tuesday but when I do, I think I will:

-Move the stick as it is now with the outboard ends disconnected to see if the stickiness is there. I don't remember making that check over the weekend. Of course the geometry will be different than when they are attached so I'm not sure how much this will buy me.

-Then I will hook up the outboard ends and disconnect at the sticks then move the ailerons to see if it is gone.

-At some point I was thinking of loosening the heim joints, take the ailerons to their limits, then tightening the joints at that point.

The guy at Van's actually went out to check on their birds and he said that, at least for the one he tried while I was on the phone with him, there was a small bit of stickiness at the extremes.

Some things we were kicking around over the weekend were maybe the mechanical advantage of the bellcrank is less at the stops (confirmed by Van's) and the airloads will make this a non issue in flight (also confirmed by Van's). Van's said this is not a safety of flight issue.

Regardless, I'm with you on this Dan, I want to chase this down and get it cleared up. I want my controls like butta at all extremes if that is possible.

Regarding rivets, I checked those and they seemed to clear.

I'm thinking I'll find the smoking gun during the "twizzle" check but we'll see.

I'll send out an update later this week. Thanks again for all the help.

Not sure if this was mentioned yet, but my main aileron tubes would just barely touch the seat ribs in the fully deflected position. I just filed a little off the rib and all was good.

newbie dumb*$$ mistake

I went to my hangar at lunchtime (lucky me; it's only 10 minutes on country roads from my office) and continued obsessing.

Then had an aha moment, followed by feeling like a moron.

When I installed the ailerons on the wings several years ago, I had failed to observe the admonition in the plans to shim the outer hinge with washers or even a fabricated spacer as necessary to remove side load. Instead, I'd assembled them with the exact washers shown in the plans. Upon loosening said outer AN-3 bolt at the outer end of each aileron, then removing the washers, the problem became instantly obvious. The hinge bracket wanted to be somewhere else. After some bending, fussing, getting down on my knees and scrutinizing, I reassembled. The control stick now falls to the side once either aileron travels upward more than 10 degrees or so.

Not sure how I managed to overlook that, other than being a relative newbie when I assembled the ailerons the first time. Contrast that with the nearly 30 hours of increasingly frustrating obsessing I did over elevator bind. But my elevator floats freely as a result, even with the added drag of an autopilot servo. Despite that effort, I completely overlooked the ailerons and convinced myself that the stiffness was due to the roll servo when I installed the wings a couple of months ago. Duh.

Glad you figured it out Lars!

jthocker said:

Glad you figured it out Lars!

Click to expand...

Thanks, Jon. You will like my reinvented controls much better!

Flap hinge pins too long?

A strange one that I had was caused by flap hinge pins that were too long.
At nearly full aileron deflection the aileron hinge bracket was touching and bending the end of the pin. I still got full deflection but an increase in resistance.

Lars said:

or floats freely as a result, even with the added drag of an autopilot servo. Despite that effort, I completely overlooked the ailerons and convinced myself that the stiffness was due to the roll servo when I installed the wings a couple of months ago. Duh.

Click to expand...

Yea I had a false aha moment concerning the roll servo. Good that you found your problem easily.

I can't wait to get out to the hangar after work to take another look at mine.

should this become 'standard procedure'?

Thanks guys for all this...I've now added a number of things to my annual inspection! ...and another reason you shouldn't try to do the whole thing by yourself!
One other comment; air loads almost never 'make it better'....they invariably CAUSE things to bind, flex, etc.
or.......(would you listen to an appliance repair guy who says " oh, that grinding noise in your dishwasher will go away....." ?????)

Found the problem!

Man, I feel a huge weight off my shoulders! I found the problem and fixed it!

I'll keep you all in suspense for a while. So, I get to the hangar tonight and I checked for the twizzle. All my torque tubes twizzled very well, thank you, which wasn't good news.

So, I laid down on my brand new 6 wheeled creeper (if you don't have one, get one) and crept under the right wing bellcrank. This is where my auto pilot servo is located. As I moved the aileron, I noticed a very slight flex of the bracket that it is mounted to. That ain't right! I then checked the twizzle of the small auto pilot servp push rod out there...IT TWAS TWIZZLE-LESS!

I had some washers on either side of the heim joint on one end but only one at the servo end. I remembered that Van's told me the other day that they added those tiny washers on either side of the heim joints at lower end of the sticks to prevent this problem from happening. What I needed was 4 of those tiny washers. I was sure I didn't have any spares.

I dug around in my spare hardware drawer and low and behold, I had 4 of them!

So I put them in and I suddenly got my twizzle back!!!! The ailerons move like butta. I was sure that I had exonerated the servo over the weekend. I remember disconnecting it and moving the stick but thinking that the problem was still there. Hmmmm.

So, pay attention to your auto pilot servo push rod and made sure you put those tiny washers on either side of the heim joints or else you'll lose your twizzle! (OK, I just love that word).

Thanks for the help and may the twizzle be with you.

This thread coundn't be timelier ...

...I'm at exactly the same point in final assembly, and had noticed some binding in the R elevator that didn't exist in the left. Like the rest o' ya's, I figured it was the roll servo. Now I know there's a whole lot more to be checking out in this rigging process! Much appreciated.
Interesting that the diagrams from TruTrak for the installation of the roll servo don't mention those little #$%^ washers.

I thought I was done with the bushings but this problem made me take a close look at them. You can really make them work well with a bit of work. I'm amazed how nice it feels now.

I bought a lifetime supply of those little washers (10) from Vans in case I have to take things apart someday and loose one.

After about 8 hours of work at the hangar today, I think I'm now ready for my inspection in the 18th. I just have to vacuum up real nice and finish up some paperwork.

when we put the RV-3 together for the final time, we had a little "stickiness" at the end of travel in one direction. It took forever to chase it down, but turned out to be that we needed an extra washer as a spacer between the bearing and the inboard hinge support. Too difficult to explain without pictures and drawings, but the bottom line is that you have to keep shimming and bushing until it is right. The drawings are a starting point, not the final solution.

Paul