Where should I look for corrosion?

[FloridaMan]

One of my biggest fears of something that should be easily avoidable here in FL is missing something simple to inspect for and letting it get out of hand. Where are the points where I should look for corrosion? I stick my head up in the wheel wells and look at what I assume is the spar, but are there other areas and inspection plates in particular that I should remove and look through with a mirror or a scope? 

[Alan Fox]

The cage where all the tubes come together at the back of the cabin where it bolts to the wing is a big one..... The spar members inside the wheel wells , The splice plate at the bottom of the center of the wing that joins the two halves , The wheels , the stack tubes where the gear shock discs go over....If you have the old goodyear pucks (5 mains 4 nose ) they are rusting out from the inside...where steel horns attach to the tail control surfaces , anywhere the exhaust is close to the engine mount......  Florida is corrosion heaven , worse on the West coast , than the East Coast, as the wind blows from the west , It will blow salt air off of the Gulf onto your plane ,     

[Marauder]

Look up service bulletin 208 for the cage, main spar in between front and rear seats and engine mounting frame are the just a few of the places you can being to look. I also look for corrosion onHeim joints and any exposed metal. The good news is that much of the aluminum has zinc paint on it.

[FloridaMan]

The good part is that I do keep it in a well-sealed hangar now, but I had to work to get this one. My last one would get water in it when it rained and it would sometimes take days for it to clear out. I take as best care of this plane as I can. 

[N33GG]

Agree with the above information.  Also...

 

Remove one or two inspection panels under each wing and take a good look with a mirror and strong flashlight.  The first Mooney I almost bought had crystals growing in one wing that looked like a high school science fair project.  The rest of the plane looked pretty good.  It had been on the west coast.  I passed.

 

If I lived in Florida, I would probably have my aircraft fogged every year, even if kept in a hangar.  Might be overkill, but that is what I would do.

 

Not necessarily related to the salt water environment, but another problem area is the center spar (see Marauder's post above) where corrosive material may be spilled in the cockpit and drain back to the spar where it sits and works on the aluminum.  One of the worst things is a battery that is dropped and lost in the cockpit that leaks battery acid.  Everything spilled eventually makes it to the spar.

 

It is always a good idea to be on the lookout for corrosion and treat it before it becomes a problem.

[FloridaMan]

I spotted this. This is in the front right corner in the left wing wheel well. I'm assuming this is rust running off somewhere. The texture is not corrosion; it's paint flaking off. In places where it's come off completely, the aluminum is clean. The food rule I have in my airplane is nothing other than water for drinks for that reason. I've hard horror stories about spilled cokes in Pipers. 

 

[scottfromiowa]

Corrosion X application every two years ='s peace of mind....

[Jamie]

I've hard horror stories about spilled cokes in Pipers.

No doubting you, but why? What makes coke so bad? Other than the sticky mess, I mean? Is it the sticky mess? Does that draw moisture?

[carusoam]

Extremely acidic...loves aluminum.

Not good for your stomach either...

Best regards,

-a-

[Alan Fox]

Extremely acidic...loves aluminum.

Not good for your stomach either...

Best regards,

-a-

I have to disagree , I have never seen coke rot out an aluminum can before , But I do agree its not helping things either....

[Marauder]

I have to disagree , I have never seen coke rot out an aluminum can before , But I do agree its not helping things either....

 

I heard the same thing and it came from my grandmother back in the 60s. Another one of those urban legends. There is belief that Coke lines their aluminum cans with food grade plastic liners (not true) to prevent it from eating away at the can during storage. Also, the human stomach has much more stronger acids at work for digestion than Coke. 

 

What I would worry about is dissimilar metals at work against each other. Not sure how much of that we have in our planes, but that is a real problem for some industries (like plumbing). Anytime you have dissimilar metals in direct contact and introduce moisture you are likely to have some issues. 

[Piloto]

Antares 

 

The corrosion shown on the picture is from the steel bracket itself. Does not look serious but it should be cleaned and recoated.

 

José 

[Alan Fox]

I heard the same thing and it came from my grandmother back in the 60s. Another one of those urban legends. There is belief that Coke lines their aluminum cans with food grade plastic liners (not true) to prevent it from eating away at the can during storage. Also, the human stomach has much more stronger acids at work for digestion than Coke. 

 

What I would worry about is dissimilar metals at work against each other. Not sure how much of that we have in our planes, but that is a real problem for some industries (like plumbing). Anytime you have dissimilar metals in direct contact and introduce moisture you are likely to have some issues. 

We have a LOT of dissimilar metals in our airplanes....Our spars have hundreds of steel huck bolts in the spars , steel cages , steel control horns....

[carusoam]

The ph of coke is measurably low. (Near a ph of 4 = acidic) Aluminum is sensitive to acidic environments. Have you seen the aluminum battery box?

The inside of a coke can is polymer coated. The Coke Can is probably not the same alloy used in airplanes either. Battery boxes are supposed to be painted (polymer coated). My M20C tried to digest it's battery box between annual inspections.

Leaving loose water in the back of your plane is not recommended.

Disagree if you want to, but I don't think it is a good idea, wether it is an OWT or not....

How did I do?

Best regards,

-a-

[carusoam]

The sheet metal of cans gets coated and printed as flat sheets prior to being formed. Aluminum is believed to be not good for brain health? Nobody liked the aluminum taste in their beer. Most people have stopped using it for cooking utensils as well.

Best regards,

-a-

[carusoam]

Average shelf life of a coke can is <6 months.

Average shelf life of a Mooney is infinitely greater, I hope.

Just sayin'

Best regards,

-a-

[Marauder]

I think Marauder's grandmother was a smart person that has been discounted by her progeny...

Just sayin'

Best regards,

-a-

She died of Alzheimer's... Seriously, being associated with the industry I decided to take a closer look at this discussion. Carusoam is correct, the pH is somewhere between 2.5 and 2.7. So, Grandma was right and was Carusoam. As was he correct about the lining of the cans. They use a polymer coating, not a plastic liner.

The difference is that the acid found in our stomach is hydrochloric acid with a pH of 1.5 to 3 and Coke uses phosphoric acid. Phosphoric acid has a wide variety of uses, including as a rust inhibitor, food additive, dental and orthop(a)edic etchant, electrolyte, flux, dispersing agent, industrial etchant, fertilizer feedstock, and component of home cleaning products. So, it looks like it will eat your teeth and your plane but your stomach should be okay.

[bnicolette]

Found just a little on mine during the annual. This is located under the panel on the right side where the exhaust comes out on the 201. This pic is of corse after we sanded and painted. Apparently a "hot" spot for some corrosion?

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