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Can never be too careful..

PatMac

Active Member
After review from my DPE, I closed up my 14 H/S. While moving to storage, I noticed a small scratch on l/e. Hardly visible through the blue film... Upon peeling back, I saw this. Mothership reco'ed rebuild or replace.... Talk about a kick in the shorts... DPE has a few options to explore....

No idea how it occurred or when.... but lesson learned. No more 10 neighbor tours of the shop while building...
20220327_180443.jpg
 
I had some hangar rash on my part and the Vans replies were replace the part, always. It's CYA.
 
Let’s see - 200 mph, highly stressed environment - seems like CYA works both ways . . . :rolleyes:
 
I'm not an A&P and I'm still early in my build. When you have to replace something like this, I envision you drilling out all the rivets securing the skin. Ouch.

Then what about riveting the new skin? Do you flush rivet what you can then blind rivet the rest? Do you seperate the spar from the ribs so you can flush rivet everything?

Good grief this train of thought is terrifying. And then I start to think what if this was the wing leading edge. :eek:
 
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Take another look.

Do you replace your prop every time it has a scratch?

No, you sand it out. It is not an instant failure point, but could contribute to fatigue failure if left untreated, or is out of possible treatment limits.

I would scotchbrite/400 grit sand the area and then see how it looks.

The answer could be the same, but also could be perfectly acceptable.

EDIT: OK, I took another look and it could well be a fracture from manufacture - in which case it will be a free part. -)
 
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Scratch test

Try this test to convince yourself: take a scrap strip of 2024 sheet and put a sharp scratch across it, then bend it. Guess what is going to happen?
 
I’ve scuffed out light scratches in a skin, but if it was a crack all the way through I’d call Vans and take their advice. Im not an airplane engineer so I ask them. Building for 6 years and I’m still not sure where on the spectrum between “scraped a cleco on the skin” and “deep gouge” that you need to replace the skin.
 
Industry standard is typically that you can burnish out up to 10% of the skin thickness, with all kinds of caveats and exceptions.

Hard to tell from a picture, but that looks like it's at least 1/2 way through. In fact, it might just be a shadow or something, but in the deepest part it almost looks like it's all the way through?

It's a bummer, but the right way to fix it is either with a dime/dollar patch (hard to do in that location, and a bummer on a new airplane) or replace the skin.
 
Crack

Just speculating 🤔 that it almost looks like a bend crack when HS was bent? That hurts to have to take everything apart and redo it.
 
Repair? ... Maybe.

I recently made a repair to a compound curved surface which had a three inch long crack. The repair was made IAW AC 43.13. You might ask the folks at Vans if such a repair would be acceptable in your case as this may be a lot simpler than replacing the entire skin. In any case, listen to the engineers!

 
I recently made a repair to a compound curved surface which had a three inch long crack. The repair was made IAW AC 43.13. You might ask the folks at Vans if such a repair would be acceptable in your case as this may be a lot simpler than replacing the entire skin. In any case, listen to the engineers!


This is the type of approach that I would take. Yes, this should be considered a crack (much too deep to be considered a scratch) and needs to be addressed. However, a well done patch like the one above seems like a very reasonable approach to addressing this problem and WAY less work than rebuilding half a wing, not to mention the loss of structural integrity if too many rivet holes get enlarged. If this area's bay is accessible via one of the access holes, you can patch with a doubler from behind, after opening and deburring the crack, and then fill with epoxy for cosmetics. If not, you could make an access hole/cover for that bay. The benefit of a doubler behind is that the entire patched area can be covered with filler before paint and will be invisible after paint.

I understand Van's position in responding to you, but let's consider that they cut a hole bigger than this and in a similar position in the leading edge for the stall sensor, with no doubler or other support. My 10 wing came from the factory with two holes drilled in the leading edge for this sensor. So it is not really as clear cut as MUST REPLACE entire wing skin. MANY of structural parts have holes drilled in them with no adverse effect. I agree that some analysis must be done and can't really expect Vans to do it for you. The AC mentioned in this post is the bible for repairs like this.

Also, there is about a 0% chance this crack was caused by one of your visitors.

Larry
 
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+1 on Ron's suggestion. A fellow RV builder around here repaired wing leading edge damage from a dropped bucking bar using the same technique, worked out great.

And as Blain said, it does kinda look like a grain crack which would imply that the skin might not have been positioned correctly when the LE was formed. Might want to check that with Vans.

HTH

Dave
 
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I understand Van's position in responding to you, but let's consider that they cut a hole bigger than this and in a similar position in the leading edge for the stall sensor, with no doubler or other support. My 10 wing came from the factory with two holes drilled in the leading edge for this sensor. So it is not really as clear cut as MUST REPLACE entire wing skin. MANY of structural parts have holes drilled in them with no adverse effect.

Larry

Not to mention the two huge holes I cut in the wing leading edge of my -8 for Duckworth landing/taxi lights!
 
C'mon, guys, you're using a different part of the airplane and locations that are less loaded, in your discussion. There's zero relation, as far as concern or loads, to this defect. What's more, the factory has already given their recommendation. What the heck?

Dave
 
C'mon, guys, you're using a different part of the airplane and locations that are less loaded, in your discussion. There's zero relation, as far as concern or loads, to this defect. What's more, the factory has already given their recommendation. What the heck?

Dave

I'll say it again. Listen to the engineers!
 
C'mon, guys, you're using a different part of the airplane and locations that are less loaded, in your discussion. There's zero relation, as far as concern or loads, to this defect. What's more, the factory has already given their recommendation. What the heck?

Dave

You're suggesting the leading edge of the wing is less loaded than the HS? The factory gave A recommendation. That does not mean it is the only way to do it. Their recommendation may be the safest, but it doesn't mean it is the ONLY way to successfully address it. Strongly recommend an engineers opinion, but Van's response was likely the only one available without analysis. The OP can have someone analyse this and make a recommendation.

I retract a bit, as rebuilding a HS skin is WAY less effort than a wing skin. Sorry for missing that in the original post. Let's not forget that it could take several months for the OP to get a skin from Van's, so given the bird is ready to fly other options may help quite a bit. NOt like the old days, when you needed something you ordered it and got it the next week.
 
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Not sure I would run off to my computer and pull up the Vans store so quick. Replacing an entire panel is adding a project to your project.

Repairing dents and scratches in aircraft sheetmetal has been going on as long as the material has been in use. Its mostly about rebalancing the stress load to a panel.

Why not take some time and look in AC4313 for some guidance?
This document has been around far longer than Vans builder support and used as guidance throughout the industry, GA through Part 121. It contains some excellent info on the philosophy of Sheetmetal repair, as well as methods.

As mentioned by others there are established proven repairs to sheetmetal. Sanding a scratch is one. Stop drilling and doublers additionally. All are covered in “Acceptable Methods Techniques and Practices” AC 4313.

Here is a link to an EAA article on the subject:
https://www.eaa.org/eaa/aircraft-bu...building-articles/metal/repairing-sheet-metal

Cheers!
 
You're suggesting the leading edge of the wing is less loaded than the HS?....

I'm saying the load at the locations where holes were being made for the stall warning vane or a landing light, is differently loaded than wherever the damage is on the HS. Since the stall warning hole and landing light holes on the wing are outboard, the local stresses are probably less for that part of the wing. That's because on a wing, the loads decrease non-linearly towards the tip, with the root being much more highly loaded. On the HS, we would say that, too, except for that outboard elevator hinge, which tends to give a point load to the HS close to the tip. Also, the HS is a thinner section.

Comparisons are invalid.

Dave
 
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