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Rodent Infestation caused corrosion

N

nerdwithoutacause

I'm New Here
So after a long break from building (and my workshop) due to "life getting in the way", I was organising/inventory-ing my workshop this weekend. I would like to start the build again.

Sadly, I found that some rodents had nested in some of the wing parts. I had the leading edge skins and the fuel tank skins stored together, and the rodents nested in the middle.

Most of the rodent droppings/urine was protected by the blue film. On a couple of punched holes a little got underneath, but on those areas I could scotchbrite/acetone and then just rattle can prime and it was ok.

However, one of my fuel tank skins did not have the blue film on the inner surface. This has been hit quite badly. Because this is an area that is not normally primed, it tried to clean it with iso-propanol and also acetone, rubbing with a cloth. The surface looks damaged, i.e. etched.

If it was any other part I would scotchbrite and prime.... But as it is the fuel tank I am not sure how to proceed.

Photos attached. 1st photo is the condition on finding it. And second photo is after a trial cleaning.

Hoping someone can give me some good news, as I'm in Europe the shipping of these parts will be expensive :-)
1000058356.jpg1000058358.jpg
 
To paraphrase a quote from an old friend, how much does a new skin and shipping cost? Not as much as a new behind.

That looks really bad, just bite the bullet and order a new one. Or, worry about it every time you fly.
 
Wise words... I'd rather not be thinking that every time I push the throttle forward. Even if the aluminium is okz I doubt the sealant would seal properly.

I'll try to coordinate with some other local builders and when they're shipping stuff and add this skin in to a group order.
 
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That sheetmetal is 032 thick! It is plenty strong. I would hit it with a DA sander and 180 grit sandpaper. Then alodine it. My thinking is that any damage is to the surface of the metal. Sanding it won’t violate the integrity of the sheetmetal, but will clean it up to the point where the ugly is gone and alodine will convert the surface and provide a durable surface that will not corrode.

The inside of the fuel tanks on commercial airliners has a 2 part primer. Jet engines can substitute avgas for Jet-A when it is not available.

Alodine is a chemical conversion coating, not a paint, that bonds directly with aluminum and improves corrosion resistance without the risks associated with primer.
 
You might as well give the sanding mentioned a try and see how it goes. Worst thing is you get to practice with the fun goop to seal the tanks. Thinking about it, the worst thing would be doing the tanks twice.
 
rockyfatcat said:
That sheetmetal is 032 thick! It is plenty strong. I would hit it with a DA sander and 180 grit sandpaper. Then alodine it. My thinking is that any damage is to the surface of the metal. Sanding it won’t violate the integrity of the sheetmetal, but will clean it up to the point where the ugly is gone and alodine will convert the surface and provide a durable surface that will not corrode.

The inside of the fuel tanks on commercial airliners has a 2 part primer. Jet engines can substitute avgas for Jet-A when it is not available.

Alodine is a chemical conversion coating, not a paint, that bonds directly with aluminum and improves corrosion resistance without the risks associated with primer.
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I'd start with something a bit finer, such as 400 grit emery or maroon Scotch-Brite, followed by Alumiprep then Alodine. As you say, it will help with corrosion resistance. It's also an adhesion promoter for Proseal. I Alodined all my tank interior surfaces for both these reasons.

See AC43.13-1B Chapter 6, especially Section 8. It will explain what should and shouldn't be done. Also, Van's is the ultimate authority.
 
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How about asking yourself this: If you were looking to buy a plane, and the seller told you "Yeah, a bunch of rats peed all over the inside of the tank skins, but I sanded it all out and I think it'll be okay", would you be so keen to buy and fly it?
 
Agree. Replace.
Take maroon scotchbrite on a 18V random orbital and Bon Ami cleanser and sand the inside clean. Shoot self etching SEM to prime. Then you have some extra sheet aluminum to build other stuff.

Buy a couple electronic traps for the rodents. I don't use the old style because it makes a mess. Once you think the guilty parties are gone throw moth balls into nooks and crannies. Mice hate the smell. My car had a problem for a while.

I keep traps in my shop. We have squirrel and chippy problems in the mountains. I relocate them to the opposite side of the river. Someday I may tag them with red paint to see if they find their way back.
 
wirejock said:
Agree. Replace.
Take maroon scotchbrite on a 18V random orbital and Bon Ami cleanser and sand the inside clean. Shoot self etching SEM to prime. Then you have some extra sheet aluminum to build other stuff.

Buy a couple electronic traps for the rodents. I don't use the old style because it makes a mess. Once you think the guilty parties are gone throw moth balls into nooks and crannies. Mice hate the smell. My car had a problem for a while.

I keep traps in my shop. We have squirrel and chippy problems in the mountains. I relocate them to the opposite side of the river. Someday I may tag them with red paint to see if they find their way back.
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Mice don't like mothballs, you better tell that to some that i have had to deal with. I once visited a radio repeater site, the radio which was in a box about 3 ft high, 18 inches wide and 8 inches deep was full of wheat. I repaired the damage and dumped out a bag of mothballs in the bottom of the cabinet. Went back a year later and it was filled again with grain, so much for the mothballs theory.
 
rockyfatcat said:
That sheetmetal is 032 thick! It is plenty strong. I would hit it with a DA sander and 180 grit sandpaper. Then alodine it. My thinking is that any damage is to the surface of the metal. Sanding it won’t violate the integrity of the sheetmetal, but will clean it up to the point where the ugly is gone and alodine will convert the surface and provide a durable surface that will not corrode.

The inside of the fuel tanks on commercial airliners has a 2 part primer. Jet engines can substitute avgas for Jet-A when it is not available.

Alodine is a chemical conversion coating, not a paint, that bonds directly with aluminum and improves corrosion resistance without the risks associated with primer.
Click to expand...
+1

From the pic, it appears it is all surface. If you hit it with sandpaper and it goes away in a minute or two of sanding, it is a non issue. I experimented once years ago. Put 120 grit paper on a da sander and attacked a piece of 025 alclad. This has about.0005-.001” of pure aluminum on the surface. I sanded until color change, meaning i sanded through the outer layer. Mic’ed it to confirm less than .001 was removed. Took over 5 minutes of high speed power sanding to do that. So if some light hand sanding removes the corrosion, your piece still has integrity.
 
I would sand the snot outta it, then scotchbrite; then mic it, I’ll bet you cannot remove 100 thou. (Edit 1 thou - 04:45 sans coffee fat fingers)
Alodine would be my next step, but may be hard to get where you are at.

Moth balls? Have you ever smelled moth balls? (Insert joke reply to the response)
Nah. That’s like my attitude on bear spray; it’s just a condiment.
 
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Although nothing is 100%, I've found that it helps to keep a radio going in the shop 24/7. Mice don't it when people are around and a radio simulates that.
 
Dr_Dave_MT said:
<snip>
Moth balls? Have you ever smelled moth balls? (Insert joke reply to the response)
Nah. That’s like my attitude on bear spray; it’s just a condiment.
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Does kinda look like "snot" got on it!

I actually like the smell of mothballs. Also proseal. Weird.
Ok, forget the mothballs, but it worked for our rodent problem.

We have bears in the Summer. big bears. I don't spray them. I have another deterrent that works better with more range.
 
wirejock said:
Does kinda look like "snot" got on it!

I actually like the smell of mothballs. Also proseal. Weird.
Ok, forget the mothballs, but it worked for our rodent problem.

We have bears in the Summer. big bears. I don't spray them. I have another deterrent that works better with more range.
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10 mm Glock in my chest holster.
 
Dr_Dave_MT said:
10 mm Glock in my chest holster.
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Nope, but that's a backup. 1911 actually.
Airsoft. Fully automatic. 400fps. Really stings. One hit is a reminder to stay away from our house. Works on, elk bulls tearing up the trees, coyotes and wolves too.
 
Sanding aluminum...I remembered in A&P school we were taught to be careful to use the right kind of sandpaper on aluminum. Here's what I found.
  • Use the correct abrasive material. Always use sandpaper with aluminum oxide abrasive. Using silicon carbide or other materials that can leave behind metallic particles is a major mistake, as this can cause galvanic corrosion.
 
mfleming said:
Sanding aluminum...I remembered in A&P school we were taught to be careful to use the right kind of sandpaper on aluminum. Here's what I found.
  • Use the correct abrasive material. Always use sandpaper with aluminum oxide abrasive. Using silicon carbide or other materials that can leave behind metallic particles is a major mistake, as this can cause galvanic corrosion.
Click to expand...
Yes! I have dedicated files also. Silicon bad juju and also bad is a rototool wheel on an engine block! Those fine particles make it past the filter right onto the bearings. (GMC)
 
I have a pair of unused Quick Build RV7/8 tanks in perfect condition if you're interested? Based in the UK.
 
If this was the outboard leading edge, I'd follow the above advice on cleaning, sanding and coating it and then build on.
But, having just built my tanks, knowing the amount of work that goes into them to ensure they don't leak, I'd replace it.
 
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