Skin buckling and bad riveting technique?

[jdmunzell]

Hello all,

In a previous post, I mentioned about a skin buckling issue on my left wing top skin. After not getting any majic "fixes" from anyone, I was forced to really look at my problem and rethink a few things. I reviewed the exact sequence of riveting that got me into this jam and made some conclusions.

I had a couple of friends lend their time to help me rivet the two top skins onto my left wing. In order to not keep them any longer than necessary, we only riveted the skins down to the bottom row (or most aft row as it were). I figured I could lie on my back on the shop floor and easily reach both sides of the skin, and finish the job myself. At this point, before going on my own, we had followed proper riveting sequence and "fanned out" from the center of the skins...so far so good...

I don't know what I was thinking when I did this, but when I started the bottom row, I started at one end and riveted to the other end. First the inboard skin (outboard trailing edge inward toward the wing root). Got lucky here as there was buckling here.

Next the outboard skin, and this is where I got into trouble. I started at the outboard trailing edge and progressively worked my way right down the line and finished up at the lapjoint area. I didn't notice it at the time, but there wound up being a slight rise (buckle?) in the trailing edge of the skin near the lap joint area. I didn't really notice it until I clecoed on the aileron brace, and then it was real apparent!

http://s714.photobucket.com/albums/w...t=100_0855.jpg
http://s714.photobucket.com/albums/w...t=100_0858.jpg

The only solution that I have come up with is to drill out all the rivets from that bottom (or aft) row (around 70), and re-cleco everything and recheck to see that the warp has been removed. Then begin riveting again in a more even pattern to make sure there is no creep.

Before I begin this rather drastic step, I am hoping you guys will pipe in here with either other ideas, or encouragement to press on with my plan.

[JonJay]

I can't tell from the picture if the Flap Brace might help take this out or not. I am sure you have been down that path already.
In the time you have spent worrying about fixing it, you could have been done with it. If you are not already an expert at drilling out rivets, do a search and hone your technique on some scrap, then have at it. You can drill out 70 rivets in an hour or two. If you mess one or two up, dont worry about it. Make it look good cosmentically and call it a day. One or two bad rivets are not going to make a difference.
If there still seems to be some "slop" in the skin, start riveting from the center out and rivet every other hole. This will allow some of the skin to "pucker" slightly between the rivets. Hopefully it will not pucker much and you will still have an acceptable end result.
Don't get discouraged. It is all part of the process and builds character.

If you have an experience builder close by, find them and get them to look at this in person. My suggestion is coming from looking at two pictures and your description of the problem. Take it for what it is worth.

[carguy614]

Before I drilled them out I would cleco the gap fairings in every hole first to see if that will draw the edge straight. I had this issue on my 9 wings, and after gap fairings were installed and riveted they were razor straight.

Hope this solves your problem, if worse comes to worse, just drill them out and rerivet them in place with the gap fairings clecoed on.

Chris

[jdmunzell]

Thanks guys. I guess I am making too big a deal out of drilling out a few rivets ( okay..around 70 of them ). At least these are the small ones and drill out very easily!

Jonjay, like you say, a hour or two and the drilling will be done. It's all part of the challenge and it does keep it from getting boring, that's for sure!

Carguy, the -8 is a little different from the -9 in that the flap brace attaches to the bottom skin, not the top. Another -9 guy suggested the same thing you did. I appreciate the input just the same though.

First thing in the morning, I'll be drilling away...