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inktomi

Well Known Member
Sponsor
I did a very uneven job of countersinking my aileron attach bracket - the rivet head is undercut on one side. What do you think? Replace?

I emailed vans a while back, but have not heard from them on this. I'm sure they'll get to it eventually.

I would appreciate your wisdom. Also, tips on countersinking so close to things - I tried to do it by hand and that didn't work out so well.

Drilling out rivets in such thick material is not very easy, so I'm worried about potentially damaging the wing rear spar while removing this if I did want to replace it. I see there were directions in Section 5 (I think) to use a #40 drill and then punch it out, which is what I'd try here.

IMG_3380.JPG
 
I could also fill this using a syringe and structural epoxy, if that would be better than removing and replacing. I'm not sure this would be a good idea though?
 
No need to be sorry! I want to build a safe plane, not finish quickly. I'll take every precaution I can drilling out the rivets. Thank you!
 
Use a drill smaller than #40, like a #41 or smaller. Drill and snap the head off as usual. Then drill right down the centre of the rivet being very careful to drill straight. Don’t drill all the way through - you are looking to create space for the rivet to collapse into itself as you punch. I you drill too far down, the punch will punch through the shop head then you are in trouble! Then using a pin punch which fits down the rivet tap it out. You can have someone holding the shop head with some side cutters ground to lose their sharp edge and get them to twist while you tap.
 
inktomi said:
I did a very uneven job of countersinking my aileron attach bracket - the rivet head is undercut on one side. What do you think? Replace?

I emailed vans a while back, but have not heard from them on this. I'm sure they'll get to it eventually.

I would appreciate your wisdom. Also, tips on countersinking so close to things - I tried to do it by hand and that didn't work out so well.

Drilling out rivets in such thick material is not very easy, so I'm worried about potentially damaging the wing rear spar while removing this if I did want to replace it. I see there were directions in Section 5 (I think) to use a #40 drill and then punch it out, which is what I'd try here.

View attachment 65426
Click to expand...
Curious when you sent your support email? I emailed them a week ago about an issue I need to resolve and nothing but crickets....

Anyone know how long it takes these days to get an answer???
 
TASEsq said:
Use a drill smaller than #40, like a #41 or smaller. Drill and snap the head off as usual. Then drill right down the centre of the rivet being very careful to drill straight. Don’t drill all the way through - you are looking to create space for the rivet to collapse into itself as you punch. I you drill too far down, the punch will punch through the shop head then you are in trouble! Then using a pin punch which fits down the rivet tap it out. You can have someone holding the shop head with some side cutters ground to lose their sharp edge and get them to twist while you tap.
Click to expand...

Just so I have all the info - what is the fix if I DO break off the shop head and then have a rivet shank with a hole in it, and no shop or factory head anymore? Is the only option to use a full-size (#30 in this case) drill to drill the remaining "shell" of the shank out? Any other option?

I placed an order for replacement parts. Thank you all! This community is so great. It's a large part of why I chose a Van's kit.

I also bought a second countersink cage with the intent that I can grind it down to be able to fit it close next to flanges like this - hopefully that will solve the problem and prevent this from happening again.
 
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I have a bit of a long process, but it gives opportunities to make corrections.
Center punch the head
Drill first with a 1/16" bit, all the way through. Check for centering.
Drill with a 3/32 (not a #40) most of the way through. This gives room to the shank to "squeeze" when driving out, especially for long rivets like this one, and gives you something to drive against. Check for centering.
If well centered, drill most of the way with a 1/8" (not a #30), snap the head off with a 1/8 punch. If not well centered, just drill to the depth of the head, and snap off, and see what you have. Use a smaller drill to avoid the hole walls (a numbered drill set is nice for this)
Drive the shank out with a 3/32 punch, or pull out from the back with nippers on the shop head.
If done right, you'll be rewarded with a shank with a thin wall of remaining rivet and a clean hole.
 
Assuming you will be drilling from the factory head side of the rivet; it is unclear in the photo whether the part is going to obstruct access for the drill chuck. If it is in the way, then you should use a long drill bit (6 or 12 inches) to ensure that the hole can be drilled in alignment with the axis of the rivet.
 
As far as how to avoid stuff like this in the future, if youre not a master at freehand countersinking, you can either cut away one side of the cage of a standard micro-stop or buy a specialty one that will clear close quarters like that. Here's an example

www.yardstore.com

3" Extended Microstop

PN: 130003" Extended Microstop 5/16" Quick-Change Chuck or 3/8" Regular Chuck Adjustable in 0.001" increments 1/4"-28 Female Threads Cutter Capacity: 3/8" Rated for 3,000 RPM use Overall Length: 7"
www.yardstore.com www.yardstore.com
 
inktomi said:
I did a very uneven job of countersinking my aileron attach bracket - the rivet head is undercut on one side. What do you think? Replace?

I emailed vans a while back, but have not heard from them on this. I'm sure they'll get to it eventually.

I would appreciate your wisdom. Also, tips on countersinking so close to things - I tried to do it by hand and that didn't work out so well.

Drilling out rivets in such thick material is not very easy, so I'm worried about potentially damaging the wing rear spar while removing this if I did want to replace it. I see there were directions in Section 5 (I think) to use a #40 drill and then punch it out, which is what I'd try here.

View attachment 65426
Click to expand...
Scott (retired from Vans) has a video on youtube you should watch, could be helpful. search drilling out aviation rivets on youtube. this link should get you there.
Rivet Removal Techniques with DAR Scott McDaniels
 
Is the flush rivet a #4? If so I would recommend drilling and countersinking for a #5 rivet. To clarify just replace the one rivet. You will need a piloted countersink for a #5 rivet.
 
jrs14855 said:
Is the flush rivet a #4? If so I would recommend drilling and countersinking for a #5 rivet. To clarify just replace the one rivet. You will need a piloted countersink for a #5 rivet.
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Would this not create an edge distance issue? The #4 on the aileron attachment is fairly close to the edge as is.
 
That doesn't look too close. 2 times the rivet diameter measured from the center of the rivet. Rivet to the lower left looks much closer on edge distance.
 
jrs14855 said:
Is the flush rivet a #4? If so I would recommend drilling and countersinking for a #5 rivet. To clarify just replace the one rivet. You will need a piloted countersink for a #5 rivet.
Click to expand...

The flush rivet is a #4, yes. Countersinking for a #5 would solve it probably. It's just barely "off" - enough to see, but not enough to really get a fingernail under. I think there would be edge distance, not much, but probably enough. I'm out of town this week or I'd go measure. This might be a good idea though - there's a lot of chances to mess up the rear wing spar driling out these long rivets. I think they're AN470-4-8 or 9 rivets in some of the spots where the service bulletin parts are also in play.
 
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Lot's of good info already about drilling out rivets, and something every builder should be comfortable with. It's a rare builder who's never had to do it!
inktomi said:
I could also fill this using a syringe and structural epoxy, if that would be better than removing and replacing. I'm not sure this would be a good idea though?
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I don't believe that is ever an acceptable fix for a bad rivet.
 
I saw some posts about fixing a bad countersink by filling it with epoxy and then re-countersinking it. I thought I'd mention it, juuuust in case.
 
inktomi said:
I saw some posts about fixing a bad countersink by filling it with epoxy and then re-countersinking it. I thought I'd mention it, juuuust in case.
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Nothing wrong with asking. And I'm not an A&P just a builder, so take it for what it's worth. Either way, acceptable methods are in AC43-13B.
 
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