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Worst screw up yet, what should I do??

aarvig

aarvig

Well Known Member
While assembling the wing skeleton of my RV-9A I was riveting the number two rib from the wing root to the rear spar/W907B/W907C doubler plates. Of course, this rivet toppled over in grand style and I had to drill it out (hindsight 20/20 I should've left the little bugger but I didn't and now I have an even bigger mess to fix :mad::mad:
1.) Can this be repaired in a structurally sound manner?
2.) If so, HOW?
3.) Should I bite the bullet and replace the rear spar/rib and doublers? (If this is the case I have a lot of rivets to drill out).

Here it is from the front:
DSC_0024.jpg


DSC_0025.jpg


Here it is from the rear:
DSC_0026-1.jpg
 
Probably not the end of the world. I'd send an email to Van's and work on something else for the weekend. Chances are you can go up a rivet size or use a screw. You might have to use a doubler on the shop head side of the joint.

I had to replace my rear spar due to a shop mishap- that isn't fun and I think this is a minor setback in comparison.
 
You'll need to drill out the hole and go with a larger rivet. Just drill what you need to on the spar side. If that doesn't completely clean up the hole in the rib, you can just add a small doubler on that side.
 
Mel said:
You'll need to drill out the hole and go with a larger rivet. Just drill what you need to on the spar side. If that doesn't completely clean up the hole in the rib, you can just add a small doubler on that side.
Click to expand...

When you say drill what you need to on the spar side do you mean just drilling deep enough through the rib/spar but not into the doubler plates? Or just drill the whole thing wide enough to clean up the hole on the rib?
How thick should the doubler be and does it need to have more than one rivet in it?
Thanks for your time Mel. I was glad to see you looked this over.
 
He means drill from the spar side a hole large enough to clean up the spar side. Don't worry about the rib side. If it's still a little ragged after drilling, make a small doubler (like a wide washer) to drive the rivet through. For extra support of the rivet shank, you can set the rivet wet with a little epoxy or fill the hole with structural adhesive and then redrill it before setting the rivet.
 
Or just drill #27 and put in a #6 screw and nut or #19 & a #8 screw and nut. Might need to countersink and put a flush screw.
 
What about edge distance?

Mel,
You recommended I replace with a 5/32 rivet. I can do that. The hole is currently at the larger side of acceptable for that rivet (.1700), however, I don't have acceptable edge distance. Is this OK here?
Same with the #8 screw (although I think the hole is to wide for a number 8 screw. Going to a number 10 may work, but again, edge distance).
Any thoughts? I have the Van's engineers working on this right now too.
 
Only drill the head, drive the shank

One thing that I'd recommend going forward is that you practice drilling rivets out on scrap pieces before doing it on flight hardware. That way you can build valuable skills without risk.

When removing a rivet, you only drill through the head, and the drill bit should only go deep enough to almost touch the workpiece, but should never actually touch it. Then you can use the shank of the drill to snap off the head, and next use a drift pin of the nominal rivet shank size to drive out the shank and shop head. On thin material you can use a bucking bar with a hole in it to support the workpiece while driving out the shank.

Thanks, Bob K.
 
Bob Kuykendall said:
One thing that I'd recommend going forward is that you practice drilling rivets out on scrap pieces before doing it on flight hardware. That way you can build valuable skills without risk.

When removing a rivet, you only drill through the head, and the drill bit should only go deep enough to almost touch the workpiece, but should never actually touch it. Then you can use the shank of the drill to snap off the head, and next use a drift pin of the nominal rivet shank size to drive out the shank and shop head. On thin material you can use a bucking bar with a hole in it to support the workpiece while driving out the shank.
Click to expand...

This. With this technique having to drill out a rivet becomes a non-worry issue.
 
aarvig said:
THanks guys! I can put the scotch away now.:eek:
Click to expand...

I find tequila best for these issues; the scotch (single malt) is better for positive milestones! ;-).

It looks very fixable per the other detailed posts. I had to get size 6 CherryMax pop rivets for my HS when I misread a size #21 hole for a #12 ... and made a big hole in my rear spar.
 
Bob Kuykendall said:
One thing that I'd recommend going forward is that you practice drilling rivets out on scrap pieces before doing it on flight hardware. That way you can build valuable skills without risk.

When removing a rivet, you only drill through the head, and the drill bit should only go deep enough to almost touch the workpiece, but should never actually touch it. Then you can use the shank of the drill to snap off the head, and next use a drift pin of the nominal rivet shank size to drive out the shank and shop head. On thin material you can use a bucking bar with a hole in it to support the workpiece while driving out the shank.

Thanks, Bob K.
Click to expand...

Roger that...thanks for the advice.
 
The longer -4 rivets can be really difficult to drive out. A tip I was shown was to drill through with a 3/32" bit after breaking off the head. This relieves all the load and makes it easy to remove. It also works if you use a 5/64" on -3 rivets.

Also, do not use an air drill to drill the head as it wanders too much. Battery drill on low speed to make sure you get centred and then higher speed into the head.
 
Ditto Paul's suggestions. I got a new Li powered drill for Fathers Day, and the control is awesome -- I can turn the drill bit slo-o-o-owly to geet it started so it doesn't wander.

For a -4 rivet I use a #30 bit to drill through the head, snap the head off, then run a #40 all the way through the rivet. Works like a charm. For 3/32 rivets I find that a sharp tap with a 1/16" punch gets them out every time. I did find out the hard way that you can either support the back side with a block of wood or bucking bar, or figure out how you're going to un-bend that rib flange. :(

Now,,,, having said all that, I learned this AFTER making a big egg-shaped hole in my rear spar that looked a lot like yours. I ended up having to find a -5 rivet. Van's said I could use a -4 even though the hole was oversize, but I wasn't comfortable with it. Good luck! It's fixable.
 
To all the other suggestions, I would also add that when punching out the old rivet on a thin flange, I will place a socket over the shop head to keep the flange from bending out. If it does it's a pain to make it ever sit flush again. One of the most helpful tips I've learned here.
Chris
 
One more tip - ask me how I found out all these things about drilling out rivets......... :rolleyes:

With an enlarged hole (either -3 or -4) you can go up a size or 2 in length. Pre-squeeze the rivet a little (either in the squeezer or a vice) until it just fits in the hole. When you set it, you have the extra material to fill the hole and you cut down the risk of clinching.

It's almost like making your own "oops" rivets.
 
Thanks for all the ideas guys. I will definitely put them to use. Still waiting on an answer from Vans...might be awhile with OSH coming up. I'll keep you all posted.
 
The official answer is in...

I was told to scrap the wing and start over...NAH..just messing with you all!!:D The ceberal powerhouses at Vans (one of the senior engineers) reviewed the pictures I sent (I sent them pics with an engineers ruler so they could determine distances) and I was instructed to clean the hole up as Mel had told me and install a #8 NAS 623 pan head screw and to build on.
Thanks to Vans for a quick answer, great service (engineer analysis), and thanks to to you gents for all the great advice. As Bill said...now is the time to break out the single malt. (After the repair is complete of course).
 
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