Aileron twist therapeutic confession

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Just completed everything on the right aileron except riveting the trailing edge. I have a 1/4" twist. After almost a year of committed building, this is my first major screw up. I don't think I can reduce the error by much when I rivet the TE. Have read previous posts and found the obvious. Two options, build another one now or wait and see how it looks and flys.

I was hoping that this confession would make me feel better.

It's not helping.

For the benefit of us noobs, what caused this to happen? Was your bench not straight? Sorry for your pain. The 2nd (or is it 3rd?) will go much faster.

Barney, I feel your pain. Six years ago I purchased an orphaned project, and found that the flaps, ailerons, and elevators all had about a degree of twist, all in the same direction. The twist in the elevators was pretty obvoius at the rudder gap when the counterweights were flush with the HS. Picked the worst of the elevators, set it up on a slab, drilled out rivets on the bottom side of the spar, twisted the elevator the other way to cancel the error in the opposite elevator, carefully drilled the holes up to #4. Re-dimpled, squeezed. It worked better than I had expected.

Hurts to know that my baby is imperfect. But she flies fine, and is as strong as before the repair.

NB: The -7 elevators have a folded TE. Un zipping one of the spar seams should be equivalent to unzipping the TE seam.

Try un-twisting at the TE seam, see how much the holes shift laterally. Maybe the next larger rivet will cover the shift.

How much angular twist do you measure from inboard, rib to outboard?

-Roger

you probably found my post. Both of my ailerons have a twist of about 1/4". The trailing edges are flat, but there is definitely a twist in both.

no idea what I did, except follow the directions. I made sure the trailing edges were flat by following the method for riveting the trailing edge. After I partially set the rivets, I brought the ailerons in the house to check on a granite counter top. I must have been in and out of the house 10 times per aileron checking to make sure the TE was flat. When fully set, the trailing edge is flat, but when the spar is resting on the counter one side of the TE is off the counter by ~1/4".

At this point, I am installing the ailerons. Maybe I will rebuild before I am done building.

Flaps are perfectly flat. Go figure.

This is a very timely thread as I am just at this stage with my ailerons.
Using page 22-06 I clecoed together the spars, ribs, leading edge and skins in the order suggested.
The next step was to lay the aileron on a flat surface, check for twist, and then drill on the trailing edge piece.
Knowing that some others had experienced a twist I thought that I would check my work on the wing and discovered that there was a twist in my aileron, one that was not apparent on the flat table.
Typically when I line up my ailerons and flaps I " clamp" them to a long straight edge to make sure that they line up properly. Here, they did not. You can see that there is a misalignment and it would be about 1/4"



By removing some clecoes from the top surface of the aileron spar and clamping it together with the angle I was able to get the trailing edge to line up properly with the flap. The clecoes were then put back in place on the spar and then the trailing edge was drilled in this position, on the wing. The angles held every thing in place, properly aligned.



Here is a picture of the trailing edges, drilled and aligned, on the wing.



I will carefully check the alignment as I am riveting as it is quite possible that a twist could go in at that phase of the construction.

I followed this process with the other aileron and there was no twist in that surface. I am not sure why one surface had a twist and the other did not but obviously there is enough play in the structure to allow a twist with just clecoes.
It should likely be assembled on a flat surface the first time.
If a twist can occur with clecoes then it can also happen with rivets. I will check the part on the wing a few times during riveting to make sure that it is still straight

Did you rivet the spar starting at one end? After a couple of ****-ups, I found that you have to rivet randomly along the line. Maybe de-rivet and do it again.....?

Also, the trailing edge is double countersunk - alternate the sides when you do it and keep the whole thing clamped to the bench.

Hope this helps.

I found that you have to put some serious weight on the aileron and flap skins to hold them flat on the bench. Use Lots of bags of shot lead.

I have a modified assembly procedure that I believe will solve the twisted aileron syndrome. It does require that you check your ailerons together with the flaps, on the wing. At this stage you should already have a couple of wings laying around not doing anything so this should not be an issue.
After you have assembled and riveted the leading edge of the aileron together you are instructed to clecoe the top skin to the spar and then rivet in place.
It is quite possible that your leading edge could have a twist in it at this stage. If so, riveting the top skin now will guarantee that twist remains.

1. Once you have the top skin clecoed on, remove the clecoes from the bottom of the spar and slide the lower skin into position. Now clecoe the drilled trailing edges and the trailing edge extrusion together.

2. Place the assembly in the flap fixture and use a bit of foam to hold it in place.
Now cleco the bottom skin to the rear spar. This should lock everything in place.

3. Remove the aileron from the fixture and mount it on the wing. Use a long straight edge to make sure that the flap and aileron line up nicely.
If they do not then remove some clecoes and twist it into place and re clecoe.

4. Remove the part and put it back in fixture with foam to hold it securely.
Remove bottom skin and rivet top skin to spar.

5. Rivet end ribs to spar.

6. cleco bottom skin and top skin trailing edges together.
clecoe bottom skin to spar.
Remove from fixture and check on wing for straightness.

7. Replace in jig, take clecoes out from trailing edge and rivet bottom skin to spar.
Check on wing for straightness

8. Rivet trailing edge together as per plans.

This should make sure that your aileron does not have any twist.
This method assumes that your flap is not twisted.
This method does not mean that you can slack off on the trailing edge, you still have a chance of making a wavy trailing edge but at least there will not be a twist in it!!