Now what?

So I have been plugging away on my elevators since last winter and I was dimpling the RH elevator skin rivet holes having fit and drilled the skin to the frame. Well I goofed and clipped the opposing skin with the hammer while using the c-frame. Hindsight being what it is, I suppose I should have waited to get the 3" yoke and squeezed them but... As things sometimes do, they go from bad to worse trying to fix the first mistake. I tried flattening the slight crease out with a few small hits of the flat set against the backplate. All that ended up doing was adding some slight deformations and marring the surface. Oh did I mention this is on the top? Darn Murphy's law! After steaming about it most of the night, I had another look at it this morning and I think it's only a matter of a little filler then primer but I wanted to get a second opinion (or 10) on it. The slight crease is right at the end of the stiffener where it (almost) meets the spar. It seems to be a point of higher stress but I don't know if it might be a problem down the road. Replacing the skin basically means rebuilding the entire RH elevator from scratch because it's match drilled already to the frame. Thoughts?

Arrrrgh by Jim Soutar, on Flickr

The picture makes it look better than it is really. In reality there is more irregularity to the surface than can be seen.

Fill it.

Fill it, prime it, forget it. It's smooth, and shouldn't give you any problems. You could remove the rivets, separate the skin and work it a little smoother, but it may do more harm than good.

If you can still get a bucking bar in there, try this. Place your heaviest bar or plate over the high spot on the outside and reach inside with another bar. Heavy is better. Then, start tapping the tail of the last rivet near the dent. It may take a lot of taps before you see movement. Then maybe move the inside bar right under the dent and tap some more. Keep lifting the upper plate and checking progress. Probably won't be perfect, but you may reduce the filler required to less than half.

if its going to be painted build on, the painter will make it disappear. if its going to be polished, well, call and order a new one.

bob burns
N82RB RV-4

I've given up all notions that this will be a show plane and will most certainly be painted but I want to make sure it's properly built aside from cosmetic imperfections. It was more the crease that had me worried than anything. Here is a better picture showing the problem.

Arrrgh2 by Jim Soutar, on Flickr

My plan at this point is to put a little proseal in this area between the spar and the skin to ensure nothing moves to much and fill the cosmetic flaw with a little epoxy filler.

if you decide to tap it a bit more, do NOT put something steel underneath. If you hit steel on top and steel on the bottom you will stretch it and have an oil can. Use a wood or delrin block underneath.

Kent White did a video on removing hail damage from 2024T3 AC skins and he demonstrates what happens when you hit a bump with a slapper and a dolly. You can only hit it 3 or 4 times before you risk cracking. Practice on some scrap.

I dropped a bucking bar in my leading edge. I know the anguish you are feeling. I guess I know where my landing light will go

If it makes you feel any better, tell yourself you will build a new elevator after you get flying. Of course then you won't care, you will be having too much fun!

Thanks Scott, unfortunately that's exactly how I made things worse. The blemish on the left has a slight oil canning to it but no signs of cracking. Lessons learned. I keep telling myself I'm building my knowledge and experience most of all. One day I'll have a unique "collection of imperfections" that are proof of it but only I'll see them all.

If it makes you feel better, I think I built seven rudders before I got one that didn't have something wrong with it. Three cowlings, five spinners, four fuel tanks, two canopies, two vertical stabilizers...

By no stretch of the imagination am I an expert, so FWIW: Leave it alone!!!

aerhed said:

If you can still get a bucking bar in there, try this. Place your heaviest bar or plate over the high spot on the outside and reach inside with another bar. Heavy is better. Then, start tapping the tail of the last rivet near the dent. It may take a lot of taps before you see movement. Then maybe move the inside bar right under the dent and tap some more. Keep lifting the upper plate and checking progress. Probably won't be perfect, but you may reduce the filler required to less than half.

Click to expand...

Ahhh - but knowing what size hammer, where to strike it and and how hard to swing it is the art. Not something that can be learned from reading, or doing unless years of experience are gained.

I repaired cars for many years, read about "hammer welding" - you know - butt joints, weld with gas, then hammer the weld down till it stretches back to shape. Try that on a low crown roof panel. Well I tried this over and over for 15 years. Reading everything in print. Then -Then - I watched Kent White do this on a 3003 aluminum panel at OSH. I was not hitting it hard enough. Even on aluminum, he whaled on that part!! I mean he was working up a sweat. Instantly I saw what was missing. And . . . this was with a dolly behind it. Accuracy, speed and a mighty hammer swing. Lesson: Learn from a pro , and don't practice on the final product. Too bad youtube wasn't around in 1970-95. I was so happy when Ron Covell published a book.

Bottom line : +1 "if its going to be painted build on, the painter will make it disappear. if its going to be polished, well, call and order a new one."