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Replacing rivet with 8-32 screw

tyconnell

Well Known Member
Greetings,

Having sought a solution from the mothership for my plight, the recommendation came down to use an 8-32 screw instead of another attempt with a rivet.

Not sure what specific screw to use - an NAS 1801 type screw looks like it will do the trick, however I'm not sure of the following:
- Is this the right one or is there a better choice?
- How do I figure out the correct length? I need to secure about 1/4" of aluminum, comprised of several layers.
- All metal or elastic stop nut? Loctite?
- Other thoughts?
 
Greetings,

Having sought a solution from the mothership for my plight, the recommendation came down to use an 8-32 screw instead of another attempt with a rivet.

Not sure what specific screw to use - an NAS 1801 type screw looks like it will do the trick, however I'm not sure of the following:
- Is this the right one or is there a better choice?
- How do I figure out the correct length? I need to secure about 1/4" of aluminum, comprised of several layers.
- All metal or elastic stop nut? Loctite?
- Other thoughts?

Length of course depends on several factors - you want at least 2 threads after it's tight. The nut can be nyloc if not in a hot area, like under the cowl. Then you are probably better served by a metal locknut. Also, you can add a few washers to a screw that's too long.

If Van's said "use an 8-32 screw" they probably meant one from this page, like an AN515-8R8 screw: https://shop.vansaircraft.com/cgi-bin/shop.cgi?browse=hardware&product=screws

I'd buy a few of each just to have them, and no doubt one will fit.
 
I don’t see the application described but in general rivets are stressed in shear. The MS27039 series is a structural screw. The length should be chosen to ensure that the unthreaded portion of the shank is in the material you are securing and that the fit is very close- hand press fit desired. Unlike the rivet which expands to fill the hole and ensure no play, the screw can’t do that and needs to fit snugly so that it takes the shear loads.

If the fastener is not loaded in shear, then the fit isn’t as important.
 
I don’t see the application described but in general rivets are stressed in shear.

These might have been helpful.
 

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Obviously out-of round. Will a #8 completely fill the hole in all directions? The biggest mistake here would be allowing fastener threads in bearing. Measure carefully. A Hi-lok fastener would be a great choice here. Install per their directions for shear app and never think about it again.
 
I should have mentioned this - the tab on that rib flange is the only thing oversized / out of round. The underlying pieces are in good condition still.

Thanks for all the input so far. I’m still considering removing the rib entirely and replacing it, but that’s not without it’s own complications. Removing it cleanly and reinstalling may mean removing a lot of other rivets first.
 
new tab

Rather than replacing the whole rib and risking damage in the process, an alternative is to cut off the bad tab and fabricate a new L shaped tab. Rivet the one side of it to the web of the rib with a couple of rivets.

It is quite common to do this in the older kits because some of the bent parts do not fit and the solution is to cut and remake.

Or, just simply make a small aluminum doubler to go over the hole in the tab and use a slightly longer universal rivet. That joint is mainly in tension and the tab is not contributing that much in that situation.
 
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Personally, I would not remove that rib if you are otherwise happy with the rest of the rivets. Can you use a blind rivet with a washer on the side of the tab. Something like an AN9604L. I might even put a dab of epoxy around the rivet and washer and set it. It would be hard to imagine it would ever move again...

Good luck
BAR
 
Using a set of transfer punches and eyeballing the hole, a 5/32" punch does not look like it covers the hole, so I doubt a #8 screw is going to do the trick once drilled. A 3/16" punch looks like it will, but that's a full 1/8" step up, and I'm thinking edge distance will be a concern at that point.

I'm going to look at Hi loks (I'm unfamiliar with them), but I'm guessing it doesn't fix my oversized hole issue. This from the assumption that it needs a clean, round hole like everything else.

Leaning towards a fabricated L-shaped tab as suggested by PaulvS, but still considering options.

Really appreciate the brain trust here; hoping everyone is safe, healthy and happy.
 
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