RV-10 Elevator Mistake: Countersinking after dimpling

I'm going to call Van's tomorrow to confirm but I made a big mistake and I'm hoping I can correct it without redoing both elevators. On the RV-10 elevators, on the rear spar, you dimple the flanges *except* you countersink the inside top flanges because that is where the trim tab hinges will go later.

Well, at some point, I switched my elevator rear spars. Either that, or I countersinked them incorrectly. After riveting one full skin and half of the other, as well as riveting the ribs to the rear spar, I realized I have it wrong. I have the countersinked flanges facing the bottom skin, not the top skin.

My options are:

(1) buy two new skins, two new rear spars, and 16 new flanges and try again
(2) drill out ~32 rivets where the ribs connect to the rear spars, then ~100 rivets where the rear spars attach to the skins, and swap the spars.
(3) Un-dimple the inside holes on the top flanges on both sides, then countersink, and proceed with the build.

Obviously (1) is the cleanest option but costs some money and especially time. For (2) I'm worried about the damage I might cause by drilling out that many rivets. For (3), well I've never un-dimpled and then countersunk so I wanted to see if there was any advice out there if I decide to go that way.

Thanks in advance!

You know in your heart only option 1 will let you sleep at night. You can work on something else while waiting for parts.
Consider marking any part that might be confused with a felt tip pen, e.g, ‘up’, ‘left’, ‘top’, etc.

Option 2

Kirk

Why not drill out the spars carefully. Making sure you don’t enlarge the holes. Swap them over and continue.
If you’re not happy then buy new spars. You’ve lost nothing as the old ones would have had to be drilled out anyway.
If in doubt get advice on rivet removal. Drill only enough to snap the head of the rivet off. Then punch out with a weight supporting the rear side.

Over the course of the build I guarantee you’ll need to remove rivets so get some practice now.

Regards

Peter

BobTurner said:

You know in your heart only option 1 will let you sleep at night. You can work on something else while waiting for parts.
Consider marking any part that might be confused with a felt tip pen, e.g, ‘up’, ‘left’, ‘top’, etc.

Click to expand...

Well, I'm not so sure. If I go with the easy option, the bottom skin would be partially riveted into holes that should have been dimpled but are now countersunk. What's the impact of that change? I'm not clear it is something to be worried about.

Additionally, I'm not clear that if I dimple, then squeeze, then countersink, the top rivets would be significantly weaker.

I guess that's why I'm asking -- I don't know if I should be worried because I don't know the structural impact of these two issues. If it's a big deal then, yes, I will definitely try to remove all of the rivets and go from there.

kiwipete said:

Kirk

Why not drill out the spars carefully. Making sure you don’t enlarge the holes. Swap them over and continue.
If you’re not happy then buy new spars. You’ve lost nothing as the old ones would have had to be drilled out anyway.
If in doubt get advice on rivet removal. Drill only enough to snap the head of the rivet off. Then punch out with a weight supporting the rear side.

Over the course of the build I guarantee you’ll need to remove rivets so get some practice now.

Regards

Peter

Click to expand...

Agreed. If I can't just countersink in place, then yes it makes sense to drill out all of the rivets and then replace only the pieces that are damaged in that process. I do have some experience drilling out rivets. Some of them have gone better than others. I'd expect that, for example, the skins would have to be replaced because it seems unlikely that I could drill out ~100 rivets from the skins without any collateral damage.

Or can I use oops rivets in the skin where necessary? Just for sake of argument, what if I had to use oops rivets for half of the holes in that section of the skin. Is that an issue?

kirkbauer said:

Agreed. If I can't just countersink in place, then yes it makes sense to drill out all of the rivets and then replace only the pieces that are damaged in that process. I do have some experience drilling out rivets. Some of them have gone better than others. I'd expect that, for example, the skins would have to be replaced because it seems unlikely that I could drill out ~100 rivets from the skins without any collateral damage.

Or can I use oops rivets in the skin where necessary? Just for sake of argument, what if I had to use oops rivets for half of the holes in that section of the skin. Is that an issue?

Click to expand...

"Oops " rivets are actually the ones Boeing uses in the first place. Call Vans, Always go the the engineers when you're dealing with critical structure.

Update: I called Van's (my first time doing so) and they were amazingly helpful. The concern is that you don't want the shop side of the rivet against the razor edge of the countersink that ended up on the bottom of the rear spar. So they told me to cut and match drill a stiffener that goes inside the flange of the rear spar so that those rivets will now go through the skin, the flange, and finally the stiffener. I will need to adjust the length of the rivet, if necessary.

Additionally, the dimples that aren't supposed to be there will cause an issue with the trim tab hinge. They advised against dimpling the trim tab hinge, but I can countersink it. When I do, I yet again will have a razor's edge, so I need another stiffener.

So, I'll drill out the rivets I already put into the errantly countersunk flange, and then assuming I don't destroy anything, I'll replace the rivets after adding a stiffener. I'll add a stiffener for the other elevator (where I hadn't yet placed any rivets) as well. Finally, when attaching the trim tab piano hinge, I'll need to countersink both of those and add a stiffener.