[alpinelakespilot2000]

It's kind of hard to tell from this picture, but my right elevator skin pillows a little bit between the last four rivets (clecoes) toward the trailing edge. The pillowing is not terribly obvious (though its only, as luck would have it, on the top surface) but I'd like to eliminate it as much as possible. Any sugggestions for how to deal with this? The only thing I can think to do is to add some rivets in between the existing ones. This will pull the skin down nicely. However, then I have extra rivets showing (probably no big deal) or I'll have to fill and deck cloth over them. Any other ideas?

 

[jferraro17]

Steve-

I can't offer a solution, but I can recommend what NOT to try...

I have had very little luck filling it with epoxy/filler. Way too much sanding, and then the pillowing turns to "scalloped" looking epoxy. I'm afraid I've created twice the work trying to fix the pillowing.

Anyway, good luck finding a fix-

Joe

 

[scard]

Just set the rivets and move on. Wow, listen to me, no really, things will change a little when the rivets are squeezed in the (not so) matching dimples. Also, you'll be amazed the first time you park your new machine is out in the sun and see the skins changing shape and size right before your eyes due to the heat. I would be even more hesitant to add rivets in between.

 

[alpinelakespilot2000]

Just set the rivets and move on. Wow, listen to me, no really, things will change a little when the rivets are squeezed in the (not so) matching dimples. Also, you'll be amazed the first time you park your new machine is out in the sun and see the skins changing shape and size right before your eyes due to the heat. I would be even more hesitant to add rivets in between.

Yes, sometimes I just have to stop myself and say "move on" so that maybe I can get to flying sometime this century. It's amazing that now that I'm finally getting back to finishing the empennage parts, I can't even remember or even find all those "flaws" that I stressed about during their initial construction 3 years ago. I suspect this will be one of those things I'll never think about or notice later. As Joe suggests too, trying to fix minor cosmetic-only problems with filler might just make more work without significant improvement. I'll put these away for now and come back to them later.

Thanks for the suggestions.

 

[noelf]

Adding more rivets (my 2 cents) will probably not solve your problem. Adding rivets between the existing rivets will most likely result in additional "smaller" pillows between the rivets.

The cause of this condition is:
1. the skin was not absolutely flat for the entire length of the edge as it was drilled.

2. the temperature of the skin when initially drilled (cold) is considerably different than now (hot). I would not think this is as big of a contributor as is #1 above. Years ago there was considerable discussion on the process of heating the wing skins with a heating blanket to "expand" the skins as they were drilled to the wing ribs. Then, when everything cooled down, the skins would "shrink" back to the nominal size and this would result in "tight" rivet lines and edges. Not really a factor now with pre-punched everything.

3. A build process note in the construction manual (12 years ago) at one point sugests that as you start at one end / edge, progressively drill the holes in order. Put in a cleco, and move to the next hole in sequence. When ready to rivet, install rivets in the same order in which the holes were drilled. This would help to eliminate the "pillow" factor.