snoopyflys

snoopyflys

Well Known Member
I have seen rust as most of us have, but I am not sure how to spot corrosion on alumumin. I searched the forums without luck, so anyone have some pics or links to share of misfortune of aluminum corrosion.

Thanks,
 
there are different kinds.

I think filiform is the one that looks like little bug tracks, a very small squiggly line. I've seen this starting on edges when moisture was present.

i don't know the names of the other types, but a white frosting look is common.if it is very bad it will flake off from the parent material

here are some pictures : http://www.airforums.com/forums/f441/aluminum-corrosion-42647.html
 
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Surface corrosion is the most common form. It exists EVERYWHERE on exposed aluminum. It's why we have to polish aluminum aircraft. Usually is appears as just a gray dull discoloration of the skin but does have squiggly lines that look like miniature lighting bolts. All this will come off with a VERY light scotch bright pad (blue or green). However, don't do anything with it until you are ready to treat it with alodine and primer. Left alone on ALCLAD aluminum it will remain without any structural damage for a VERY long time. Don't get freaked out by corrosion. If you live near the coast it will be a bigger deal. I suspect within 5 or 10 miles max will rapidly accelerate the process.
 
So White chalky stuff uh...

Thanks for the replies. Fortunately I haven't seen of that just yet. And being that I live about 50NM inland from the Gulf of Mexico coast, I wasn't sure what to expect. I haven't used alodine before I primed parts I have built so far. Not sure, maybe a mistake. But I have tried to leave the Alclad parts as is. I don't want to start another big discussion on priming as that topic has been cussed and discussed elsewhere. I just hope that what I have done, will provide me several years of flying once finished.

Regards and thanks again.
 
Dan,

50 miles inland shouldn't really be an issue. Primer wars will continue forever. You will be fine. I would alodine and prime any extrusions however.
 
snoopyflys said:
Thanks for the replies. Fortunately I haven't seen of that just yet. And being that I live about 50NM inland from the Gulf of Mexico coast, I wasn't sure what to expect. I haven't used alodine before I primed parts I have built so far. Not sure, maybe a mistake. But I have tried to leave the Alclad parts as is. I don't want to start another big discussion on priming as that topic has been cussed and discussed elsewhere. I just hope that what I have done, will provide me several years of flying once finished.

Regards and thanks again.
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Hey, you should do a little experiment- take some pieces of scrap al, both alclad and "bare" and set them outside somewhere they can get rained on. you could even take a light salt solution - a1/4 teaspoon of salt in a large glass of water and let it sit on the aluminium. You should see some corrosion pretty d q. this would be for you to see for yourself what kind of corrosion is likely to happen in your area.
 
Ok, Is this what I think it is...?

While removing the vinyl from W-703 skin this evening I found this white feather looking stuff under the protective coating near the edge.

(Sorry for the fuzzy pic.)

34nkzee.jpg


Is this what some are calling "filiform" corrosion or just my imagination or paranoia? If it is, is the fix to lightly buff it out, Alodine and prime? Or since I don't have Alodine handy at the moment, use a self-etching primer to slow/stop this from becoming worse? BTW - my completed HS has been hanging in the garage for over a year now and I don't see this on outer skin (inside is primed with self-etching primer).

Danny, I think I just may "plant" some AL in the garden to see how long it takes to chalk up. I have a Rib, alcald sheet and some scape extrusion that I will donate to scientific discovery on my part. Thanks for the suggestion.

Kind Regards,
 
That looks to me to be leftover adhesive scum Dan.

Corrosion is going to look and feel coarse, whereas the normal aluminum surface is wonderfully smooth.

FYI, I have owned airplanes on the south side of Houston for 30 years now. Little primer on the Spam Cans, and no bad corrosion. I have lots of aluminum scrap laying around the hangar, exposed to the temperatures variations and dew - no significant corrosion. If I leave a toolbox open in the hangar, the steel stuff rusts overnight - no aluminum parts corrode.

Your airplane (or airplane parts) are not going to dissolve without warning. Use common sense, check things once in awhile, and you'll be fine. Prime per your desires, but don't be too worried about it. Yes, we live close to the ocean. No, stuff doesn't oxidize away overnight. That's where the sheet metal is all AlClad.

Paul
 
Not corrosion from what I can see. Looks more like adhesive from the plastic. Filiform is more gray/black. Remember the pure aluminimum layer (ALCLAD) is supposed to corrode. It will keep the corrosion away from the structural alloy underneath.

I did just remove my blue plastic on the wings and found some light corrosion. I will go to the airport today and see if I can get a good photo and post it later today. I am in no rush to clean it up. When I do, I will polish it away and apply Alodine 1001 (clear).

Again, it's best to leave it alone it is not going to hurt anything. At some point when you prep for paint the painter will scuff the surface and prep accordingly. It'll go away then.

You can "plant some AL in the garden" and it'll still be there in 30 years. Soak it in Pepsi and good bye.
 
Filiform Corrosion

Are you ready, its ugly. Don't turn your head. The good news is, it won't hurt a bit and can be easily cured with just a little work.

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HAH!!! Call that corrosion? That's not corrosion! THIS is corrosion!!! Go on, ask me what I know about corrosion! GO ON! ASK ME! Ahhhhhhhahahahahahahahahahaaaaaaaa.... *begins sobbing, curls into foetal position*


207ucmu.jpg


263eseo.jpg


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Or, as I explained it to Vans:

"I have a very early RV8 empennage kit, which I started 11 years ago. 10 and a half years ago, my wife became pregnant with our first daughter, and my project unfortunately had to be shelved, with much regret.

I stored the kit in our garage as well as I could at the time, but unfortunately I left the shipping paper in it, which in the end analysis was a Very Bad Idea.

A wandering family of mice subsequently found the kit to be a wonderful home ("look honey, aluminum siding!"), and while I was raising my family, they were raising theirs. And again. And again. And again.

Apparently this was a mouse family genetically disposed towards large bladders and little self control.

Lacking any form of decorum or respect for the wondrous flying machine in my imagination that the kit represented, they freely and often did as mice will do, again and again, all over my kit.

The result was the varying degrees of corrosion seen in the attached photos, which show the very worst affected piece, others have no damage at all, and some in between.

While I am under no illusion that this particular piece must be replaced, I am wondering what, if any of the other parts are recoverable, For example, if a piece only has some very fine filigree corrosion as per IMG_5117.jpg, can that be polished out, alodyned and then etch primed?

Or do I simply resign myself to the fact that the complete kit is now only good for practice, or alternatively making stylish mouse urinals out of, which I shall do until I can possibly afford a newer, prepunched kit?

Your earliest (and gentlest!!) response is much appreciated."
 
Holy Chalk Batman!

Chris, so that's aluminum corrosion. Sorry to hear of your blight and uninvited guest. Thanks for the pictures. Hope someone from the forum offers advice on what to do short of starting over.

Tony and Paul, thanks for the replies and words of encouragement. As Paul once told me, this is a learning experience. And it is, with every rivet driven:rolleyes:.

Regards,
 
snoopyflys said:
Chris, so that's aluminum corrosion. Sorry to hear of your blight and uninvited guest. Thanks for the pictures. Hope someone from the forum offers advice on what to do short of starting over.
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Thanks for the thought, but I've already made up my mind to start over.

When my RV finally does fly, I will know it is as good as I can possibly make it - and that doesn't involve starting with parts that may be technically okay but have had so much material taken off that I can't think about anything else as I strap one of my girls into the back seat.

Also, the new kits are all prepunched, and go together a heck of a lot faster. I've probably already spent more time cleaning corrosion than it takes to build a prepunched empennage....

Making lemonade from lemons, I have a full empennage kit that I can practice on, knowing that it will never fly. And this way, while I save up for my QB, I can learn whole new skills, like making new pieces using corroded parts as templates....

I know it may sound like a horrendous a waste of time and effort to others, but I know how I work. This is a a good solution path for me.
 
chinch said:
While I am under no illusion that this particular piece must be replaced, I am wondering what, if any of the other parts are recoverable, For example, if a piece only has some very fine filigree corrosion as per IMG_5117.jpg, can that be polished out, alodyned and then etch primed?

Or do I simply resign myself to the fact that the complete kit is now only good for practice, or alternatively making stylish mouse urinals out of, which I shall do until I can possibly afford a newer, prepunched kit?

Your earliest (and gentlest!!) response is much appreciated."
Click to expand...

Light surface corrosion is not a big deal. You will need to hit it with some scotchbrite in a die-grinder. Then treat and prime. Anything more than light corrosion gets hard to remove and it's just easier to replace the parts. Once it begins to exfoliate as one of the pictures show, the corrosion has entered the grain of the alloy (inter-granular) and the part is junk, or as in your case, one very nice mouse urinal.

At a minimum, I would get some Corrosion X or Boeshield T-9 and coat the entire kit with the stuff. It might take a couple gallons, but It'll stop further decay. Also, buy a cat.

I think if I were in your situation, I would take the time to fix all that corrosion now. I am sure many of the parts are salvageable and any that were I would clean, treat with alodine (1201 on the inside and 1001 on the exterior) of all the parts. I would prime everything with a good 2-part primer. I bet you can save most of the kit.
 
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