Unless Europa has (have) made a change in materials, you have aluminum
(aluminium) tubes in those locations, not galvanized steel. A magnet will
help to convince you which it is. Since these are a heat treated Al alloy
the proper procedure is to first remove the dense oxide that results from
the heat treatment (best done with some rather nasty chemicals) and them
prime with zinc chromate primer (if you can get it).
You can probably get away with good mechanical cleaning instead of working
with the nasty chemicals to remove the oxide - try fine grit sandpaper
followed by a thorough cleaning (soap and water should do it, but be sure to
dry the tubes thoroughly) and then, with minimum delay, spray on zinc
chromate primer, available (maybe) in small spray cans from Aircraft Spruce
(it is in their catalog but I recall that they would not sell it to me when
I inquired a few years ago - "hazardous" stuff, you know).
If you would prefer to have the job done commercially, a better solution
would be to have the tubes anodized. Specifications for automotive Al parts
usually require .0002 to .0003 inch thick anodic coating but architectural
Al requires 0.0007 inch thick (we expect our buildings to last longer than
out cars). If you are worried about the corrosive effect of proximity to
the ocean, specify dichromate sealing of the thicker anodize.
Having said all this I must admit to leaving these parts untreated in my
a/c, trusting the dense heat treat oxide film to do the job. The climate
here is benign with little rainfall and low humidity and I don't live or
store the plane near the ocean so the tubes will survive a long time without
corrosion.
Best regards,
Rob Housman
Europa XS Tri-Gear A070
Airfarame complete
Irvine, CA
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com]On Behalf Of Jeremy Davey
Subject: Europa-List: Primer for Zn-coated steel
<jeremycrdavey@btinternet.com>
Can anyone suggest a primer I can use on Zn-coated steel - i.e. the aileron
torque-tubes and pitch pushrods? If it was available in both pots and
aerosol cans, that would be ideal.
I tried red oxide cellulose primer and that just wouldn't stick :-(
Regards,
Jeremy
Jeremy Davey
Europa XS Monowheel 537M G-EZZA
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