HS rear spar holes misaligned
 

Hi all.

I'm nearly done with my HS - riveted the rear spar to the skin on the top side without issues, riveted it to the bottom right side...and then the holes on the bottom left side have a slight misalignment :(



Even though the misalignment is less than 1/32", that's enough to make the rivets not go in straight:



I'm pretty sure I drilled these straight, and had no mishaps while riveting the ribs. I followed the instructions religiously.

Any suggestions on what to do here?

I assume using a drill to make the holes match again is a bad idea?

I tried putting a little force to make it align, but it only makes the skin start to bulge, so I stopped.

The other thing is that it's about 40degF colder today than when I drilled these - the metal wouldn't deform this much with such a small temperature variation, would it?

Thanks everyone in advance!

If you hold a couple of clecoed at and angle to help it along and squeeze one River, it often will pull and hold the parts aligned and the rest will be straight.

I tried that, but the skin doesn't move, just bulges :/

I literally just went though this last night. I laid the HS on it's side and started dropping rivets into place... several times I got to areas that were like in your picture and I couldn't put a rivet in there. What I found that if I started from the inner section and moved outward with the squeezer it pulled it enough to align everything back up.

Get yourself a few tapered awls or machinist scribes. The work very well to line things up.

My HS 1003 spar had slipped on the punching machine so the outboard 20 or so holes wouldn't line up with the skin either. It was about the same misalignment - a little over 1/32. It was very clear where the offending hole was as they were exactly 1" centers then one that was 61/64 then back to 1" again.

But I noticed it at the drilling stage as I couldn't get the skin clecoed to the spar to match drill it in the first place. So I'm not sure if you have the same issue.
I required a new spar.

Van did point out that they punch 10 or so at a time on one sheet then shear it into 10 spars then bend the flanges. So it's possible there are more out there with the same issue.

Cheers

Richard

opps rivets
 

How about drill to #30 and use opps rivets? Same head size, but larger shank.

Try to avoid using opps rivets at all cost. They can pull out over time. Using one in a line is OK but not a bunch of them. You are better off drilling them up one size and putting in larger rivets.

What about the oops rivet makes them pull out over time? Does the smaller machined head work it's way loose because of the larger diameter shank? I have not heard this before.

Thanks all for the suggestions, I managed to get this done, and my HS is now completed :)

The way I did it was similar to some of the suggestions above, but instead of an awl or cleco, I used a #40 dimple die I had, which better supported the hole instead of risking deforming one side - slowly used it on one hole to force the skin into alignment, then put the cleco on the next hole (rinse, repeat 31 times). I also bucked these rivets instead of squeezing to make sure they didn't bend.

A -3 oops rivet has about 30% less bearing area than a standard -3. Not only that, but the larger shank means that the tearout cylinder, the surface area that needs to shear in order to pop the head off, is 16% smaller. It's not like they're only half strength or anything drastic like that, but simple math shows that they are probably substantially weaker than their honest brethren.

Vans designs are, by and large, relatively conservative with healthy margins. But Van himself is known to defend those margins as very necessary hedges against the unknown and unknowable. So I wouldn't mind using an oops rivet every 100 or so holes, maybe one in ten where it isn't critical, but I sure wouldn't recommend putting more than two or three in a row.

Thanks, Bob K.