corrosion protection

[matthewurban]

I'm planning on alodining my airplane for corrosion protection and am curious how important it would be to alodine after the final holes are drilled? would that be a problem if I choose to just alodine the parts before final drilling so I can start riviting right after putting everything together?
Or even corrosion protection between the skin and the rivet? Im planning on painting the skin prior to riviting. Any recommendations on how to go about this? Ive heard that if you apply to thick of a coat that the rivet wont set appropriatly.
thanks!!

[Bryan Cotton]

Anodize or alodine?

[matthewurban]

oops my bad. I want to alodine

[MichaelFarley56]

While I'm not expert, it would seem logical to me that if you're going to go to all the added time of alodining your entire airplane, you will want to apply the alodine after all the pieces have been final drilled, deburred, dimpled, etc. Basically you'll want to apply the alodine right before final riveting of the assmebly.

In most cases, corrosion will begin around rivets, bolts, edges of skin, etc. and if you spray on a part then updrill, you're exposing that metal back to the air (or water). For true and complete protection, alodine the parts as the last step.

Where do you live? Remember that 6061-T6 has excellent corrosion properties, so unless you live in a salt air environment, it may not be needed.

Good luck!

[Bryan Cotton]

I agree with Mike. Also alodine is not a thick coat. It forms a layer on top of the aluminum via a chemical conversion. It would be no problem to alodine with the holes in place and then rivet. Try it on scrap.

I alodined everything on my RV4 tail. I alodined wing spar doublers and the spar underneath on my former C140 project where my IA required it. I primed my hummelbird parts where they riveted together. I am doing nothing on my Waiex.

If you alodine your 6061 structure it should be good for one or two hundred years.

[N111YX]

I alodined my entire airframe. The only reason I did it was because there was a 55 gallon drum of the stuff at work and I thought that it was no big deal. Well, Alumi-Prep acid etching solution was used first, then rinsed, then dried, the alodine, then rinse and dry...for every part. That's a lot of extra time and Alodine is a carciogenic. You may re-think it as unless you are near the ocean, your airframe is very likely to last longer than you and the next guy, too....

[matthewurban]

I live in MN so I would only have to deal with salty airports during the winter. But im starting to rethink if the alodine route is worth it considering the extra work and dealing with its carciogenic properties. What would you guys suggest as a good alternative? Seems there are some good alodine based paints I could use.
In reference to the skin I was talking about painting not alodine. I would like to paint the skin the final coat than rivit it together. But is that true if I do this I could apply too thick of a coat for the rivets?
Thanks for all the input!!!

[daleandee]

What would you guys suggest as a good alternative?

Have a look at ACF-50. Amazing stuff used by the government and the airlines. Aircraft needs to be retreated every couple of years but treatment on a Sonex would be easy once you had the equipment. I've used this stuff in the aerosol cans and it is quite amazing:

http://www.aircraftspruce.com/catalog/pdf/ACF-50-BROCHURE.pdf

If you're going to paint you should do that before applying ACF-50 as it will wick out of every crack and crevice for a while after treatment.

FWIW,

Dale
N319WF

[Rynoth]

= would that be a problem if I choose to just alodine the parts before final drilling so I can start riviting right after putting everything together? !

Just to comment on what you said above, keep in mind that you will ALWAYS want to dissassemble and deburr parts after final drilling, prior to riveting. At no point in the project will you drill (upsizing or not) and then rivet without deburring in between.

[Darick]

What would you guys suggest as a good alternative?

Have a look at ACF-50. Amazing stuff used by the government and the airlines. Aircraft needs to be retreated every couple of years but treatment on a Sonex would be easy once you had the equipment. I've used this stuff in the aerosol cans and it is quite amazing:

http://www.aircraftspruce.com/catalog/pdf/ACF-50-BROCHURE.pdf

If you're going to paint you should do that before applying ACF-50 as it will wick out of every crack and crevice for a while after treatment.

FWIW,

Dale
N319WF

I used CORROSION X, probably the same kind of stuff as ACF-50, on my Ercoupe...it got into every tiny space and wicked out for a few weeks so we know it was doing its job. That is what I'll using on my Sonex.