a scratch

How would ya'll go about repairing a scratch in aluminum skin.
This particular skin belongs to the underside of the fuel tank.
The scratch in question being 1.5" long and very fine. Not really deep but will catch yur fingernail. Thoughts?



S_tones

Touch Up

Pricey, but people rave about it.

http://aircraftspruce.com/catalog/cspages/touchprep.php

buff/sand

you can carefully sand then buff bringing to a nice smooth surface and etch prime and move on

I have the same scratch in one of the tanks. Was trying to get a cleco in one of the holes and missed and put a nice 3-4" long scratch right through the blue plastic. I plan to lightly sand, apply some alodine and move on.

gbrasch said:

Pricey, but people rave about it.

http://aircraftspruce.com/catalog/cspages/touchprep.php

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$62!!!!!!! Holy smokes. I remem ber buying some from Stein when he first found out about it and he got a good deal and sold it to us for something like $43.

At the moment, Stein has it on his site for $52.

that's quite a mark-up by Aircraft Spruce.

Henkel must be making the stuff with fleks of gold.

Choices, choices

s_tones said:

How would ya'll go about repairing a scratch in aluminum skin.........The scratch in question being 1.5" long and very fine......Thoughts?

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Several ways. Most require a bit of elbow grease.

You don't say if the aluminum is painted or not. If NOT painted, here are some options ranging from the cheapest to most expensive approach:

#1. The cheapest way is to work the local area with a small sanding block fitted with 1000-1500 grit wet and dry. If so inclined you can continue to 2000 grit which will restore some of the surface luster again.

#2. You can buff out the scratch out using the appropriate polishing accessory fitted to a Dremel or similiar. You have many choices here.

#3. You can work the area with a very fine "unitized" wheel fitted to a drill motor or die grinder. A very fine Scotchbrite Wheel will also work but these choices may leave the area "milky" looking unless the luster is restored with further polishing. Best to try on a test piece first to get an idea of what to expect.

#4. Meguiars has unigrit sanding system that will work. You can use a Micro-Mesh kit designed for aluminum. You can even use Micro-Mesh for Plexiglas which basically consists of super-fine grades of sandpaper.

#5. The way I would do it (because I already have the stuff) is work the area over with Nuvite Grade C polish and compound polisher. Just a minute or so with that arrangement and that scratch would soon be a forgotten memory.

Here's a dumb question. If you're going to paint the airplane, why not just hit it with a maroon scothbrite pad and call it a day? It's about 1 minute's worth of work.

I've gotten rid of lots of scratches like this. Am I doing something incredibly bad here?

jcoloccia said:

Here's a dumb question. If you're going to paint the airplane, why not just hit it with a maroon scothbrite pad and call it a day? It's about 1 minute's worth of work.

I've gotten rid of lots of scratches like this. Am I doing something incredibly bad here?

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I hope not. If so, I am in trouble also as this is my remedy. If the area is going to be painted, such as on the outside skin, then the area is going to be sanded (or scotchbrited) and primed, then painted. The scratch will be covered with appropriate barriers to corrosion and will not be visible, problem solved.

Thanks

Thanks as usual for many good ideas.

S_tones

jcoloccia said:

Here's a dumb question. If you're going to paint the airplane, why not just hit it with a maroon scothbrite pad and call it a day? It's about 1 minute's worth of work.

I've gotten rid of lots of scratches like this. Am I doing something incredibly bad here?

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Nothing bad at all. Sikorsky recommends that for minor skin scratches in their CH-53E and S-76 SRM's (Structural Repair Manual). I usually use 220-grit sandpaper with a light touch to quickly take off any raised metal, then maroon Scotchbrite, then 400-grit paper. A quick MEK wipedown, some Alodine, a little primer... and you're done.