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Twisted aileron after one skin is riveted

RVFan671

Well Known Member
Building my -10 with riveted TE and it is really warped after riveting the top skin and counter balance. Bottom skin and TE are not riveted in place yet so I'm looking for opinions and suggestions on how to proceed. I'll break down my steps and attach a picture of the 7/16 inch difference in height of the TE.

I was able to get the TE to lay flat when I had weight on the bottom (laying on top side) and removing half the clecos on bottom skin and cleco the TE to the wedge. But it reverts back to the twist after removing the TE and weight so I don't think i can rivet the bottom skin?

Steps I did:
- didn't final drill anything since the holes were final size from factory.
-dimpled all my skins including the nose skin which shouldn't have been, so I had to countersink the counterbalance.
-riveted the counterbalance to the nose ribs and spar assembly before riveting my top skin (plans call for counter balance riveting after top and bottom skins are riveted)

My thoughts on fixing:
Drill out counter balance rivets and all the top skin rivets and restart riveting the top skin. I'm not sure how to keep things flat as I rivet though. One thing I read on the forum was to rivet randomly on the top skin versus what I did which was start and one end and work toward the other.
 

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I think you identified the culprit. It is easy to push a meaningful wave into the skins by riveting continuously in one direction.

If it were mine I would start by gently finding out if the loaded twist can be untwisted back to straight. If so then I would match drill the bottom side as some things would then be slightly out of alignment.

I personally would be leary of taking it apart and presuming your top side holes would still be where they started.
 
Followup after riveting things together

Wanted to post an "after" status so others in the future can learn. I started out with a 7/16" twist and after some re-doing, I ended up with 1/16" twist. I do not and won't know if this will impact flight characteristics (heavy wing syndrome) for years into the future so maybe I'll need to build it from scratch down the road.

I removed all the rivets in the previously riveted top skin to spar as well as the counterbalance rivets. I tried to torque the spar a bit for correction and that seemed to have visual impact but didn't measure anything at that point. Next I re-riveted the top skin then clecod the bottom skin and trailing edge together weighting things down. It was able to hold form with 3/32 or a little more twist than that (big improvement). I went ahead and riveted the bottom skin next. Inserted the trailing edge again and still the same twist or less when adding clecos when it is weighted down.

I mixed up 20g of proseal (requires much less) and applied to the wedge and inserted it carefully. I then weighted down the aileron and inserted clecos throughout the trailing edge, into my 1" aluminum angle that was used on the other aileron so holes were already drilled in it. Also added clecos to main ribs (the most in and outboard ribs) and counterbalance. I riveted the counterbalance and main ribs with weight on the aileron while proseal was still not kicking off although that shouldn't matter. I waited a week for proseal to dry then removed clecos from the 1" angle but left weight on while cleaning out the dimples and holes. Added rivets from the underside and put rivet tape on them, all while upside down on the table. Started the backriveting process and finally removed weight. When I checked it was 1/32 to 1/16 twist at this stage. I then put rivets in the other side (I alternate rivet heads on top and bottom side to help reduce risk of warping/twisting) and weighted it down and riveted them.
 
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