Spar tube corrosion

[Tree top pilot 13]

Are there anyone who has had a problem with this? I am almost ready to cover and was thinking of 2 part epoxy paint...not primer....on the spar tubes and drag struts. All the wood will be sealed up. What does your manual state to do here? I would like the airframe to be safe....but not looking for it to last 20 years either. There is a ton of debate over what should be done here and there on the interweb. Just wondering what others have done before I douse them with something...........

[EDMO 1078]

I have had 2 sets of spars - One coated inside and out, the other just on the outside. Both are about 20 years old and look good.

You can use a tennis ball or tape to seal one end, and then slosh the inside and pour out excess paint.

I would at least use epoxy primer on the outside, or better yet, use a self-etching primer, and then a coat of epoxy on all metal parts.

Dont think you will add that much weight, and more protection is better, IMO. I put either Kilz and spray urethane or 3 coats of urethane varnish on all wood parts.

Ed im MO

P.S. You can buy self-etching primer in a spray can at Lowes, and other places. Real Handy. My body-shop friend says it sticks better than epoxy primer, and you dont have to use alumiprep or alodine for it to stick.

Edited 20 May 2012 by Ed In Missouri

[Av8r3400 1179]

Unless you are float flying in salt water I would seriously doubt you will ever see any appreciable corrosion on your spars.

After 15+ years living outside, my project Kitfox's spars were near perfect. Fabric was crap and the coatings were crap, but the internals were just fine. I plan to just recover and go.

[dholly 718]

, keep the change!

Totally optional, IMHO. The manuals do not instruct you to do it, so I did nothing to my Avid Mk-IV and Avid+ spars. There's nothing in the KF3 or KF4 manuals instructing you to do anything either. The builder of my KF3 did nothing, however, the builder of my KF4 did alodine those spars in and out. He was an A&P and might well have been influenced by his time around certified aircraft, who knows? Perhaps most telling is that my factory built Aerotrek A240 SLSA has nekkid spars too. And I doubt it was to cut corners, the plane is very well built. If I absolutely, positively felt something was necessary (ie. living oceanside or in constant high humidity), I would just get an appropriate length section of house gutter, add some alodine and roll my spars in it. Doesn't need to be pretty, and a lot lighter than two-part epoxy paint.

There are TONS of 20+ year old Avid and Kitfoxes flying with nothing but dust on the spars. Just sayin'....

[akflyer 1427]

Gotta go with Doug on this one... Alot of guys are scrathing their heads trying to figure out how the factory advertises a plane at 450# and theirs comes in at 620# and does not fly anything close to the factory specs.

I know I only changed a few things on mine and it turned into a 572# pig! I am still planning on putting mine a diet but have not had a chance to yet. I think there is a huge tendancy for us to what if these things to death. If we try and engineer out all possible ways to mitigate the slightest possibility that something extremely remote could go wrong with one certain area of the airframe, then apply that to the entire airframe, we find where the extra 200# of crap comes from. Risk versus reward I spose.