Drilling out Rivets

N770TX · #1 01-02-2009, 09:46 AM

I know a few have done this before... but I couldn't really find the same question in the forum search. Due to a wing sitting in the wrong place and a few unfortunate drips from an AC unit I find myself removing the top outer wing skin and the leading edge (there is some corrosion spots on the skin and I want to make sure the spar underneath is cleaned up and re annodized if necessary - will probably replace the skins as well. Here's the question - I've been VERY careful in drilling out the old rivets (only made a couple of "wish I'd done better" ones - out of a million). The issue is that the expansion of the rivet shaft when setting the original rivets causes a very slight enlargement of the hole that was so carefully made to tight tolerances in the first place. Its not visual but placing a new rivet in any of those holes is not a close tolerance fit and there is some play. If this was just a couple of rivets I wouldn't worry, but over a whole wing?? I'm sure setting a new rivet will expand to fill the slight enlargement but... should I use a longer rivet? Should I redrill and go oversize everywhere (yuk!)? Or should I not be concerned at all and just get on with it? Thanks, Doug drewry

TREDONK · #2 01-02-2009, 10:04 AM

Have you tried the cheater rivets ? 3/32 head with 1/8 shanks.

Geico266 · #3 01-02-2009, 10:26 AM

Standard rivets are pretty sloppy even in a standard drilled "virgin" hole. I re-skinned a wing and had the same questions. I was told and IMHO, you can use the same standard rivets if the holes are only slightly enlarged due to the old rivets. If you "bumped" the hole with a drill you might want to look into "opps rivets" as stated in post #2. The head is the same size, the shaft is the next size larger. They set different than the standard ones, so be prepared for another 1/2 second of bucking.

GAHco · #4 01-02-2009, 10:42 AM

Quote:

Originally Posted by TREDONK

Have you tried the cheater rivets ? 3/32 head with 1/8 shanks.

These are the true Oops rivets. -3 = 7/64"

http://www.gen-aircraft-hardware.com...s_oversize.pdf

We stock the popular sizes.

Jeff R · #5 01-02-2009, 03:28 PM

I would be cautious about using a whole mess of oops rivets. With the larger shank, there is less head to hold the skins on. I would call Van's before doing this.

GAHco · #6 01-02-2009, 05:20 PM

Quote:

Originally Posted by Jeff R

I would be cautious about using a whole mess of oops rivets. With the larger shank, there is less head to hold the skins on. I would call Van's before doing this.

Great point, that's why the NAS1241's are better than the NAS1097's in this instance. The are 7/64" dia. that is between the 3/32 and 1/8.

Whenever an oversize fastener is used bolt, rivet or otherwise, you want to start with the closest oversize you can to the original. If you check AC43-13 I believe you will find these acceptable. ( mine is at home).

These rivets were designed for such repairs, not to be used for original construction, that is just not their purpose.

Have the good weekend, Bye for now.

paul330 · #7 01-03-2009, 04:58 AM

Might be a bit of a pain with so many rivets to do, but you can pre-squeeze them - use one size bigger and gently squeeze the rivet in a hand squeezer and you will find that it fills the hole and won't clinch whne you set it.

captainron · #8 01-03-2009, 11:49 AM

Tom Brink is right. There has been so much talk over the years about "oops" rivets, and the oversize rivets most people are familiar with are the 1/8" shank rivet with the head being the approximate diameter as the standard 3/32" rivet. A much better choice is the 7/64"rivet available from Tom at GAH.
Here is a pic I posted once before showing a standard 3/32" rivet on the left, a so-called "oops" rivet in the center, and a 7/64" rivet on the right. Notice that the 7/64" rivet has a head diameter almost identical to the standard 3/32" rivet, but notice also the increased head holding area available over the "oops" rivet. Not only that, but the 7/64" rivet has a normal flat head like a normal rivet, not that funny head with the bump on it like the 1/8" "oops" rivet. I believe that Van's sells the 1/8" oversize rivet as an "oops" rivet, so that's all most people know about. There is a much better choice available with the 7/64" rivet.

You can even make your own rivet gauge for them if you want. Sorry for the blurriness.

There is a similar 9/64" oversize rivet available for replacing 1/8" rivets instead of having to go with bolts or 5/32" rivets.