Replies to This Discussion

Permalink Reply by Dr. Edward M. Moody II on July 31, 2009 at 10:40am

Hi Jesse,

6061-T6 is more corrosion resistant than many other aluminum alloys but that is a relative statement. History tells us that Napoleon had his soldiers' uniforms made with shiny aluminum buttons... very snazzy for that day and time. The buttons corroded and fell off as they were exposed to the elements. Some cite this as one reason his troops were defeated in the Russian winter. Aluminum loves to oxidize. Back to the 601XL now.

I would definitley start over and replace any parts that had the corrosion shown in your photos. That is the minimum corrective action I would endorse. I used zinc oxide primer from rattle cans on the entire inside of my plane as the build progressed... I recommend the same to every builder. I have heard about the weight issue and I don't care. I would do it again.

I got all my primer from Aircraft Spruce.

Ed

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Permalink Reply by Dr. Edward M. Moody II on July 31, 2009 at 11:03am

Link to AS web page for zinc oxide primer.

http://www.aircraftspruce.com/catalog/cspages/ptizincoxideprimer.php

Ed

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Permalink Reply by Jesse Halbleib on July 31, 2009 at 11:39am

Thanks Ed.

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Permalink Reply by Chris Aysen on July 31, 2009 at 11:33am

Jesse - I viewed your photos; is it possible some outside substance (besides water) found its way onto the aluminum or the rivets? I have purposely left out some pieces of 6061-T6 out in the elements and have never witnessed that kind of corrosion.

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Permalink Reply by Jesse Halbleib on July 31, 2009 at 11:38am

They were kept in a rented storage facility along with other common household items. The building was new at the time when I rented it.

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Permalink Reply by Clemens Kramer on July 31, 2009 at 12:02pm

In the pictures where you see the cleco's Would suggest dissimiliar metals created the corrison. On the picture with the hole in the leading edge looks like the corrosion started on the outside. Was it leaning against something metal at or near that point?

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Permalink Reply by Jesse Halbleib on July 31, 2009 at 12:06pm

the spar and spar doubler are both 6061-T6. They were part of the kit. I had my rudder leaning against the wall of the storage unit but not against the leading edge.

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Permalink Reply by Robert Haines on July 31, 2009 at 9:43pm

Oh my, Jesse,

I'm in the middle of construction and I really want to avoid this.

The corrosion is very localized, which is interesting. When I see something "rust", usually the whole piece is covered before anything "rusts" through. This would indicate that there was some notable event taking place, such as condensation stopping at those points or a direct contact with steel. If that was normal corrosion, there would be a lot of aircraft having the same problem. Please provide a little more details if you can.

What I've been doing (and I can't say that it's been tested) is coating my contacting surfaces with Rustoleum primer and paint. Regular WalMart stuff. I realize that the internal parts have been traditionally coated with zinc-chromate, but the whole outside of the craft is normally protected with nothing more than enamel primer and paint so the same type of system should be adequate for the internal parts as well.

Hope this helps.

Robert

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Permalink Reply by Jesse Halbleib on August 2, 2009 at 3:11pm

I found rodent droppings in my storage unit which leads me to believe that possibly rodent urine is the cause. Only problem is that airplanes get rodents in them all the time. They build nests and do there business on and in the aircraft. That being said I would think that there would be concern about this with all types of aircraft.

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Permalink Reply by Jerold Ebke on August 3, 2009 at 5:57pm

Rodent urine is a definite no no. It will destroy steel in antique cars by severe rust. Also here in Nebraska, a man purchased an old plane of some type, got it started and was flying back to his home airport for inspection when a wing folded with fatal results. The final news item said failure of metal structure due to rodent urine related corrosion.

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Permalink Reply by Bruce Case on August 4, 2009 at 4:16pm

Your pictures really looking like some other agent is causing you corrosion. You might expect some milkiness to the look of your skins after storage but certainly nothing like what you have. If you have rodent the uric acid is extremely caustic to aluminum and a definite possibility. In terms of primers Zinc Chromate is going away due to environmental and health issues and being replaced by the new Zinc Phosphate. Aircraft Spruce has it as their part number 09-02127. Rust-Oleum is probably not a good choice as it is very heavy. You want something that etches the aluminum so that it bonds well and Zinc Phosphate would accomplish that. If you want to notch it up a bit you could use commerical products like Veri-Prime from DuPont or the two part etching primers from Randolph which I used on my RV project. Unfortunately those don't come in spray bottles.

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