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Aileron rib flange

stigaro

Well Known Member
I'm working on my ailerons now and recently riveted the top skin to the spar. After doing the left one, I noticed a distinct bulge between the spar and the first rivet in the middle nose rib that corresponds to the edge of the nose rib flange. I then took a look at the right aileron and noticed the exact same thing. Since I've already blind-riveted the spar to the ribs (or the skin to the spar in the case of the left aileron), I don't want to take this apart now, so I realize little can be done at this point. I buffed out the left nose skin as much as I dared to try to smooth it out and can probably live with it as is.

Just curious if anyone else seen this faceted edge in the ailerons? I certainly couldn't see this while the nose skin was cleco'd to the spar. It only appeared after the pieces were riveted together.
 

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CH 5

RIB FLANGE FACETING
As a skin wraps around the leading edge of the horizontal stabilizer, vertical stabilizer, or wing, among others, the skin must pass over the forward edge of the rib flange. See Figure 2. Shape the front edge of the flange to prevent this edge from forming a dent in the skin as the rib is riveted in place. A similar effect will occur at the notch between rib flanges. During manufacturing, as flanges form over the curved edge of a formblock, the ends or surface of the flanges may remain straight or flat rather than conforming to the curvature of the formblock. This results in faceted, instead of uniformly curved mating surfaces. A skin riveted on top of the rib would appear faceted and a bump would occur in the skin in the area of the notch between the rib flanges. Shape-deburr the edges of the flanges especially in the area of the flange radius as required. See Figure 2.

You might want to hit the back corner with the buffing wheel.

or

It is possible you put a bit of extra down force on the back of the skin while riveting. Did you squeeze or buck the rivet?
 
I did buff the forward most tabs where most of the curvature is, but admittedly didn't focus much of my attention to the back of the aft-most flange where there isn't much curvature. Only enough buffing to smooth the edge. Obviously I should have done more. This was only visible after I set the nose rib rivets and became even more prominent when setting the spar rivets. I set the nose rib rivets with a pneumatic squeezer. I don't seem to have an issue with any other faceting, just these two ribs.

I suspect that in setting the skin to spar rivets, the swiveling mushroom set did put some extra force on the unsupported section of the tab, thus making the facet worse. I'm not sure what I could have done differently though. I've resigned myself to living with it as it seems everything I do to deal with it just makes it look more noticeable.
 
Confused you said squeezed and mushroom head. Mushroom head squeezer? or rivet gun attachment? if a rivet gun a mushroom head you could have easily caused that by being a bit not straight.

Someone on here that works at a major manufacturer said even the pro's make mistakes and all aircraft have em. so not a big deal.
 
Really a pro

Confused you said squeezed and mushroom head. Mushroom head squeezer? or rivet gun attachment? if a rivet gun a mushroom head you could have easily caused that by being a bit not straight.

Someone on here that works at a major manufacturer said even the pro's make mistakes and all aircraft have em. so not a big deal.

I have lots of them, so i must be a Pro.....
 
Confused you said squeezed and mushroom head. Mushroom head squeezer? or rivet gun attachment? if a rivet gun a mushroom head you could have easily caused that by being a bit not straight.

Someone on here that works at a major manufacturer said even the pro's make mistakes and all aircraft have em. so not a big deal.

The nose rib to skin rivets were squeezed, but the skin to spar rivets were bucked when the top skins were added. I can see how the rivet gun may have made this problem appear worse by putting additional stress on the edge of the flange since it is very close to the spar/skin rivet line.

I agree, not a big deal and I've reluctantly accepted this since I'm not drilling out all the rivets now. I think that for whatever reason, the rib flange was sitting a little proud of the skin it was supposed to support.
 
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