Skin corrosion on stored rudder

[jdmunzell]

Hello all. I am one of those builders that takes forever to build an airplane. I've had a completed rudder stored in my dry and climate controlled basement now for about 10 years. ... Yes, I know... Anyway, I took it down from up on a top shelf that was located directly below a small staircase that goes from my garage up into my laundry room. The left side of the rudder has been exposed facing upwards all these years, and was loaded up with all kinds of nasty and oily looking residue. I can't even imagine what this stuff is but possibly mouse droppings among other things. I tried cleaning it off with some lacquer thinner (the only available at the time), which cleaned up a lot of it, but left a roughly two ft. square area of left over corrosion. Most of it is minor pitting, but pitting none the less.

How do I fix this? Is this too large an area to simply compound off or otherwise buff out until the pitting is gone? Or should I think about reskining the rudder completely or even building a whole new rudder?

I will try to upload some pics of the pitting shortly.

[crabandy]

I thought I had the same issue on a lot of my stored parts, looked like filiform corrosion. Acetone/thinner didn't take it off, Soapy water and a scotchbrite pad took off the crud and it wasn't corrosion after all. Perhaps you'll luck out too!

[John Tierney]

I had a similar mouse issue with my HS, then the dishwasher dripped grey water on another part. What worked well for me after the general lacquer thinner cleanup was Nevr Dull ( http://www.nevrdull.com/ ) found in most hardware stores. There were a few spots where the corrosion had eaten through the alclad and I had to buff/sand off the alclad with fine sand paper and maroon scotbright pad and wheel on a die grinder. Sanded out the corrosion on the aluminum alloy layer (I think I also used a small brass brush; I remember the spot being bigger under the alclad) then hit it with a couple layers of self-etch primer.

[jdmunzell]

Thanks for that info on NevrDull. I will try that next to see if that will take it off.

[jdmunzell]

Okay, I tried the NevrDull, and while it cleaned up the skin from other impurities, I'm still left with very definite pitting into the skin, and a lot of it as well. It appears scotchbriting is my next step, and assuming that I keep scotchbriting until all the pitting is gone, how would I know if the remaining skin thickness is adequate? Remember this is the lower left side of my completed rudder covering about a roughly two square ft. area.

[ColoRv]

I would send pictures to Grady at GLO and get his opinion but I suspect he will tell you not to worry about it (like he did me). I guarantee you aren't corroded anything like a plane that's been flying unpainted in the humid southeast for half a decade. The painter will deal with minor corrosion.

[Wayne Gillispie]

Install a vent fan in laundry room and try to keep aluminum well away from any corrosive chemicals while building.

[BillL]

Yeah, basements are not as clean as one might think. My basement is heated/cooled and air is well circulated with an epoxy painted floor and perimeter subsurface drains that never allow water to rise. The wings are on a stand and pushed into the back nook. All is dry and no varmints, but there are a few spiders. BUT . . . there was plumbing overhead and all it took was a drop if liquid every few months to leave a surprise. After a couple of years, it all cleaned off with DI water, and a little Flitz polish (fortunately), but it made me cover them with a cotton sheet then plastic to ensure NOTHING dropped on them again.

A basement may seem clean and dry, but water & drain pipes and air jets from a dryer pipe pinhole leave evidence on airplane parts that would not be noticed if they weren't there to collect the evidence.

No harm, no foul, but a lesson learned.

[LettersFromFlyoverCountry]

The laundry room, eh? You got a water softener, by any chance?

[Sig600]

You're not alone. I finished my rudder in 2002, working on the canopy now.