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Airframe maintenance -minor corrosion

I would be grateful for any tips on removing and repainting minor corrosion that appears (mostly leading edges) so that it does not continue to spread. There are a very few areas about thumbnail size that I really do not want to take it to a paint shop for. Aircraft is C172 repainted about 10 years ago. Many thanks

UK, United Kingdom

I have this comment from an A&P/IA colleague who I maintain my plane with and who does a lot of this kind of work:

Unfortunately there is no easy way to remove that kind of corrosion. The best way is to have an orbital sander, rub down the affected area about three to four times greater than the corroded area so there are no traces of corrosion left, then treat it with alochrome, then prime and paint it.

Personally I use an epoxy (2-pack) primer, not the common zinc chromate which is frankly WW2-era rubbish compared to epoxy. I have bought a big pack so if you want some I can send you a bit

When I do small patches like that myself, I rub them down with emery paper and then prime with epoxy direct. Important to not use a steel brush or steel wool as they leave steel in the aluminium which then corrodes.

Shoreham EGKA, United Kingdom

One of the biggest challenges here, is to match the paint correctly. With about 5 dozen differing shades of white, it can easily develop into a patch work quilt effect, not particularly easy on the eye.

For small areas like that, I get the local "Chips Away', car repairer to pop in. Give him the colour match, either RAL or BS, and he does a decent job.

Again, getting the correct conditions for primer, and paint to dry, can be a PITA.

I am not good at this stuff, I tend to make a right mess, therefore I tend to leave it to the pros, who also have a habit of making a right mess.

If you are persistent, confidence when sanding is key, getting the depth and spread of the area sanded is vital, also a good idea to check what primer is actually on the wing, again, I have seen a different primer, making the paint applied, look different. Prior research may save you a lot of heartache.

Fly safe. I want this thing to land l...
EGPF Glasgow

My view is that preventing the corrosion from spreading is the main thing, and visual perfection is second.

A plane is for flying to places, and the ex-showroom beauty is not going to last 5 minutes once the average EASA 145 company starts maintaining it

For the first 3 years I was G-reg and used a JAR 145 company to do everything. They used to strip all the screw heads with power screwdrivers; I had a key to the hangar and sneaked in after hours and changed the screws with fresh ones out of a Socata screw kit

Now, my 11 year old plane has little bits of corrosion in many places, and there is no way to get a perfect colour match if touching up just a small patch. So I sand out the corroded bit and prime it, and the white primer looks OK from a distance

Also it is impossible to do a good visual job with a brush. One has to use a spray gun, or an airbrush if you are really skilled with one. But for spraying one needs facilities. There are only a few days each year when one can do it outdoors, and the whole plane needs to be masked otherwise the overspray goes everywhere. It's a lot of hassle for a small patch. I have a portable spray kit which uses a scuba cylinder and 2 regulators, but the masking takes so long I rarely use it.

A few years ago somebody did some spraying somewhere near or upwind (nobody owned up to it) and I found the plane covered in white overspray. It took me a day to get most of it off the windows but the rest of the plane is still somewhat covered on the upper surface. I paid somebody £200 to try to get it off with a power buff but it didn't do much.

One day, when I really have nothing better to do, I will get a complete respray, and then everything will match, but there is probably 10 years to go before that.

Shoreham EGKA, United Kingdom
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