Another Skin Scratch Thread

Dave Bernard · #1 03-21-2011, 08:46 PM

Allright fellow builders,

I began de-blue-plasticing my left elevator the other day and found some pretty deep scoring on the skin.

The problem is, this scoring exists in what I consider the most critical and high-stress area of the skin: the leading edge. With the bend in place, should this peice fail in flight, I could have a jammed elevator and could possibly meet my demise.

This scratch is deep enough to see in the side view of the skin, leading me to question the structural integrity of this part.

I also fear spending 30 hours building this thing and having it snap on me when I do the bend!

Replies , advice appreciated!!!!!

Hens07 · #2 03-21-2011, 08:53 PM

did you make the scratch somehow or was the skin shipped that way...just covered up by the blue plastic

Dave Bernard · #3 03-21-2011, 09:12 PM

I was shipped that way- the skin has sat in the box since day 1.

Also of note is that I already consulted Vans, the gentleman said that I could flie down the edges and buff the scratch with Scotchbrite. That still doesn't give me a warm fuzzy though.

DB

aarvig · #4 03-21-2011, 09:20 PM

I'd readdress the issue with Van's. If your kit has been sitting for a couple years or if you aren't the original owner of the kit I would understand if they wouldn't replace it. If you are the original owner and the kit isn't that old then I would hope they would pony up. I have had nothing but positive experiences with Vans. By any chance do you have a photo of the part before you took the blue off?

caryr · #5 03-22-2011, 06:55 AM

I would have difficulty imagining a scratched skin separating in flight because of the scratch.

I would work on it with a scotchbrite pad and see if it improves.

JMHO

krw5927 · #6 03-22-2011, 08:38 AM

Run your fingernail perpendicular to the scratch. If the scratch catches your fingernail (basically if you can feel the scratch with your fingernail) then it needs to be blended out. Remember that a scratch is the same thing as a crack, and there's one hard and fast rule about cracks in aluminum - they grow.

These Vans airplanes for the most part are fastener shear critical (meaning the fastener will shear before the skins fail in bearing). So in theory you could blend this skin and "maybe" still be stronger than the fasteners that attach it. Unless you have access to material allowables, though, and are comfortable blending skins and measuring remaining thicknesses, I might be seriously inclined to replace it. Especially since it hasn't been attached yet.