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Elevator counterbalance skin to rib gap

georgemohr

Well Known Member
Hi team!

Our elevators came out really nice, with the possible exception of this one issue. There is a noticeable gap between the counter balance skins and the flanges of the counterbalance ribs. Riveting did not help pull this in at all.

I don't see what I might have done different here. The skins went on these ribs very nicely and felt well aligned. The skins are VERY rigid in this configuration and have no willingness to get closer to the rib flange. I think the ribs are just "too short" by a small amount.

My inclination is to seal this gap with proseal to prevent moisture from intruding, and carry on.

Thoughts?
-George
 

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I don’t think I would be too worried about that small gap in this location, but to give you piece of mind, ask the techs at Vans Aircraft.
If I was worried about it and wanted to fix it, I would drill out those 3 rivets, clamp on both sides of the metal pieces on each rivet tightly with c-clamps, and then re-rivet them. If you are worried that there still may some sort of small gap, fill it with some structural epoxy before re-riveting. I don’t think this would make any significant difference structurally, but if it solves your problem, then it’s worth it.
 
Rubber o-ring

...I don't see what I might have done different here...

My suggestion... Get yourself some different thickness rubber (or whatever pliable material) o-rings. Place one on (around) the shop head while you rivet for the first 1/2. This will help close the gap and allow some swelling of the rivet to hold everything in place. Finally remove the o-ring and finish riveting to final shop head size.

You will find many such places in the kit where you will need this gentle persuasion to get things started off on the right foot.
 
Some fuel line for string trimmers and such works great for rivet "collars". Just trim off a little piece with a razor blade. 3/16" or so works. Puts just enough pressure to close the gap, but still set the shop head. Pops right off.

Sooo, what about the rib flanges jutting out past the skin edge?.... I'd probably spend a few quality minutes with my favorite mill file to dress and deburr that.
 
I might add something here:
I am rebuilding several parts on a -7A and find that I need clamping force from time to time.

I have a few 1in "Kant-Twist" clamps that are invaluable.

52211269767_1435ca71a9_n.jpg
[/url]kant-twist by Kent Luttrell, on Flickr[/IMG]

They are very small and fit almost anywhere.
 
If you remove the 3 rivets and use tightening cleco's on the aft side, that may work. Check with an A&P they may have that style of cleco. Good luck,
 
My suggestion... Get yourself some different thickness rubber (or whatever pliable material) o-rings. Place one on (around) the shop head while you rivet for the first 1/2. This will help close the gap and allow some swelling of the rivet to hold everything in place. Finally remove the o-ring and finish riveting to final shop head size.

You will find many such places in the kit where you will need this gentle persuasion to get things started off on the right foot.

I found it even easier to just buy some aquarium clear air tubing in a couple of different sizes and cut short little pieces to slip onto the rivet shank (shop head side). Kept a bunch lying around ready to use any time there was a gap. They come off easily even if you fully form the shop head.
 
Hi all,

Thanks for all the inspiration. I realized after much head-scratching that the root problem was my fluting on the flange of this LE. I just over-did it a bit, making the radius smaller than the radius of the skin.

Some liberal application of clamps helped flatten these flutes and pull all this together before I re-riveted it.

@FL-Mike I did just as you suggested to even up the flange and skin edges :)

Regards,
George
 

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