wing priming

[phintz]

What is everyone using for anti corrosion protection on the spars and cross tubing? Then are you roughing it up with scotch brite, then cleaning it with denatured alcohol or mek then priming?

[ken nougaret]

i haven't done it yet, but plan to soon; to use poly-fiber's white primer.will use scotch brite and alcohol to clean. i'm going to try a sponge on the end of a long stick to do inside the spars.
ken

[Av8r_Sed]

For all aluminum parts I used the Alumiprep/ Alodine conversion process with no paint inside the wing. If you do paint, this provides a good base for the primer.

Steel parts were done with the ScotchBrite, MEK, epoxy primer and Aerothane top coat.

[Av8r3400]

I plan to do what 99.9% of the builders do: nothing. I don't live near the ocean, don't plan on saltwater seaplane ops, so to me it would be wasted weight.

My project plane came from upstate New York and it lived outside most of its 10 year life. It had zero corrosion in the wing's aluminum structure when I tore them down.

[Dave S]

By most people's standards, I probably went wayyyyyyy....overboard on this.

Given the spar tube Alloy and its original heat & surface treatment (6061T6), Larry's comments certainly ring true....it's pretty darn resistant to corrosion in the first place. The materials and coatings, we and the factory, use on the planes is so far superior to what was used in the past with regard to sealing and corrosion resistance if we do nothing additional, it's still going to be better than planes of past, and many of them held up pretty good too considering.

If there is such a thing as "corrosionology"....study of corrosion....most of it is observed occurring not on an open surface or where there is good air exchange; but, where two pieces are in close contact and it gets moist and never dries out. A couple cases in point I have seen this happen on really, really old Piper tube and fabric planes.......between the fabric and aluminum leading edge formers, in/on the tubing on the bottom/rear of the fuselage.

For the wings, drag tubes and elevator push pull tube....I treated all with Alodine and Epoxy primer inside and out. The drag tubes and elevator push-pull tube were painted on the inside before assembly. Spar tubes were painted after the wings were complete. Epoxy used in sloshing the inside of the tubing was thinned severely; and, allowed to drain thoroughly with the tubes on end after sloshing the epoxy.

Have one attached photo of the wing which shows the epoxy paint on the spars with overlap onto the ribs to be sure everything was sealed well.

Probably overkill by most standards...but that's just my choice.

Sincerely,

Dave S
KF7 Trigear - Flying
912ULS, Warp Drive
St Paul, MN

[JohnB]

For all aluminum parts I used the Alumiprep/ Alodine conversion process with no paint inside the wing. If you do paint, this provides a good base for the primer.

Steel parts were done with the ScotchBrite, MEK, epoxy primer and Aerothane top coat.

Paul,
Did you alodine the spars before building up the wing or after?
I was thinking about doing the same thing to mine and I like the idea of gaining some corrosion protection without adding much weight. I wasn't sure if the alodine coating would weaken the Hysol bond to the ribs or not.

[WISDAN]

John,

I used the alodine method after building the wings so the Alodine would not interfere with the bonding of the wing ribs and other structures. You also have to be carefull not to build up any coatings on the inside of the spar to allow the spar insert to side into place without binding. Anyway this was my experience.

Dan G
Model IV-1200
Jabiru 2200

[Av8r_Sed]

I Alodined the spars and drag/ anti-drag tubes before assembly. It's a chemical conversion process rather than a coating and probably increases adhesion of the Hysol. I treated the insides of the spars too using the tennis ball method.

[JohnB]

Thanks Dan and Paul for the replies. Hopefully I will be to the point to try that before too long.