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Advice on repairing a side skin puncture

moespeeds

Well Known Member
Friend
Hey guys,

When I bought my RV8, I noticed a "pimple" on the front baggage compartment right side skin. The total width was about 5/16". Upon inspection with a magnifying glass, I realized it was actually a smile shaped puncture. Looks like at some point, something sharp in the baggage compartment went into the side.

I tapped it back flat with a dolly and hammer like a dope, and this caused the skin in the area to oil can.

So my plan to repair is to drill out the spot to about 5/8" to remove the crack and the area I stretched by tapping it flat.

I do not want to dimple and buck new rivets on the paint to install the traditional "static port" type patch. I spoke with a Boing Aeronautical Engineer who is a friend of mine, and he advised me to bond the patch using 3M Scotch Weld 08966. The final bonding strength will exceed that of rivets.

So the plan is to water jet 2 discs out of .032 2024, one 3" in diameter, and one 5/8". Glue the small disc to the center of the 3" disc, then glue that on the inside of the area, with the 5/8" disc filling in the hole and the 3" disc backing it up. I would clamp the arrangement in place while drying and throw a bullet hole sticker over the whole arrangement once done.

Thoughts or suggestions?
 

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Depending on the size of the dent, I would drill a #30 hole, dimple, and put a flush head rivet, either solid or pull rivet. After topcoat paint, it will look as if the rivet is a part of the fuselage, and no one will notice it.
 
Depending on the size of the dent, I would drill a #30 hole, dimple, and put a flush head rivet, either solid or pull rivet. After topcoat paint, it will look as if the rivet is a part of the fuselage, and no one will notice it.


Far too large for a rivet, the hole will need to be at the very least 3/8 of an inch.
 
In that area, a 2" back up would be fine using adhesive. Some filler and an airbrush with matching paint and it is gone.
 
Adding to what's been said above, the patch pieces could be easily cut by hand (no need for water jet) and I would make the inside one square as that would make it easier to conform to the curve of the skin. I'm also not sure that you really need a dime on the dollar because the small shallow void could just be filled with epoxy filler and sanded smooth.
 
I would leave it in there and if you have the paint, just dab some in the hole/bump and move on. If you get a run/bump from to much paint, just plane it off with a razor blade.
Fly not cry.
Unless you are taking it to Oshkosh to be in a show.
My three cent worth Art
 
The least I would do is open the hole up to 1/4" with file. Polish the hole edges. Glue a backing piece of aluminum. Fill the hole with filler, JB weld etc and finish with paint or decal.
 
I like the 2" square or round backing plate, with either the hole insert or filler to fill the hole, doesn't matter. If you use a square one, round the corners so it looks better and saves a bit of weight. Snips and a file are fine for shaping.

I'm not familiar with that epoxy, but 3M's 2216 B/A or West System's G/flex are both entirely suitable. I've been gluing and riveting my RV-3B fuselage together with G/flex and it holds tenaciously. 2216 is at least as good.

Prep is simple: degrease, abrade, clean and degrease all mating surfaces, bond. Tape about 1/16" away from the doubler to guard against epoxy going everywhere, and have something like a Popsicle stick that you've put a small radius on to form a fillet. The 2216 will creep more (before setting up) than G/flex will, if you use the thickened G/flex. Otherwise perhaps mix a small amount of Cab-O-Sil in either of these epoxies to prevent runs.

About 15-30 minutes after assembly, you can remove the tape. Don't wait too long or the tape may be glued to the plane.

You can use maroon Scotchbrite for the abrasion, but something coarser is better. 120 grit or 80 grit Wet-or-Dry works fine. I know a guy using 40 grit. And bond within 2 hours of the abrasion.

Yes, clamp the surfaces. You don't need heavy pressure. A few decent magnets will do fine. Perhaps four pairs of these. I chose red so that I can identify them if they wander off. Magnets do tend to do that. One magnet goes on the inside, the other outside, and that'll work well - using four pair. Two or three pair if you must, but four will be better.

Dave
 
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