Salt and Fresh Water Corrosion - Screw Replacements etc

[M20C_AV8R]

Disclosure, I am not a chemist, just a private pilot and a new plane owner

I did a search and came up with a variety of different answers. Would welcome others thoughts. I came out of boat ownership and into a plane. Basically went from one aluminum hull to another, but, a lot of the same characteristics and concerns that I have remain in various ways. I am based basically at sea level, about a quarter mile from the beach. Owning a boat, I was religious about proactively preventing galvanic corrosion, obviously a really good set of sacrificial anodes etc, but, even at a level above that and ensuring that all of the screws in the boat were coated with teff gel to put a barrier between metals (stainless and aluminum) as that is where you can get in trouble real fast. I find it interesting that I read these threads about screw replacements using stainless on our planes, but, all you technically need to do is add a corrosive electolyte i.e. water, fresh(salt) does not matter and you have the risk of corrosion between those screws and the aluminum (http://www.anzor.com.au/blog/galvanic-corrosion-keep-those-metals-apart/)

Maybe I am missing something here, but, does it not make sense if you are based in a salt water atmospheric environment to take the same considerations for proactive protection on your plane? I am fairly new to plane ownership so just trying to learn it all and ensure as I go forward I take the proper steps to protect my investment, I mean money pit.

I also understand about protecting the plane overall, mine is for the most part in a hangar and when out an about if I stay somewhere overnight the windows get covered etc on the outside.

[jaylw314]

2 hours ago, M20C_AV8R said:

Disclosure, I am not a chemist, just a private pilot and a new plane owner

I did a search and came up with a variety of different answers. Would welcome others thoughts. I came out of boat ownership and into a plane. Basically went from one aluminum hull to another, but, a lot of the same characteristics and concerns that I have remain in various ways. I am based basically at sea level, about a quarter mile from the beach. Owning a boat, I was religious about proactively preventing galvanic corrosion, obviously a really good set of sacrificial anodes etc, but, even at a level above that and ensuring that all of the screws in the boat were coated with teff gel to put a barrier between metals (stainless and aluminum) as that is where you can get in trouble real fast. I find it interesting that I read these threads about screw replacements using stainless on our planes, but, all you technically need to do is add a corrosive electolyte i.e. water, fresh(salt) does not matter and you have the risk of corrosion between those screws and the aluminum (http://www.anzor.com.au/blog/galvanic-corrosion-keep-those-metals-apart/)

Maybe I am missing something here, but, does it not make sense if you are based in a salt water atmospheric environment to take the same considerations for proactive protection on your plane? I am fairly new to plane ownership so just trying to learn it all and ensure as I go forward I take the proper steps to protect my investment, I mean money pit.

I also understand about protecting the plane overall, mine is for the most part in a hangar and when out an about if I stay somewhere overnight the windows get covered etc on the outside.

The answer is yes, dissimilar metal corrosion is a danger, especially with moisture and especially salt + moisture.  Stainless steel hardware looks good, but can cause issues in the long run, so the standard fasteners are a bit safer.

That being said, under reasonably dry conditions, most fasteners in metal aircraft are expected to have some protection.  Cadmium plating is standard on most hardware, oxide coating on nutplates, some primers have sacrificial zinc in them, chromate conversion protection, and then good ol' paint.  The advantage of planes over boats is that boats usually don't have 150 knot winds blowing over them, so if flown regularly, planes stay drier!

TLDR--yes it's an issue, but planes kept reasonably dry have lasted for 50-60 years (some without any paint or primer protection) and are still going.

[Yetti]

My grumpy IA will suggest that SS screws will galvanic corrode.      Some people near the salty sea will coat the inside of their planes with some form of oil.    The navy has done some testing on anti corrosion.    here is one   https://www.navfac.navy.mil/content/dam/navfac/Expeditionary/PDFs/S6360-AW-MMO-010_ltr.pdf

 

[1964-M20E]

Just now, Yetti said:

My grumpy IA will suggest that SS screws will galvanic corrode.      Some people near the salty sea will coat the inside of their planes with some form of oil.    The navy has done some testing on anti corrosion.    here is one   https://www.navfac.navy.mil/content/dam/navfac/Expeditionary/PDFs/S6360-AW-MMO-010_ltr.pdf

 

131 pages of light reading thanks Yetti.

 Would you care to summarize it for us literary challenged folks around here?  Not only a CB but lazy too.

 

 

[Yetti]

My summary is.    Things corrode.   The plane has lasted for 40 years without corroding away.  Original paint job too.   Lube everything that pivots at annual.  Replace anything that is worn or loose.   keep flying it.    If an engine overhaul costs $40K and I can get another full plane for a little bit more, maybe I will scrap this one when it needs and engine.   The OP said he wanted to read up on things :-)

[tangogawd]

ACF 50 and a fogging gun. Did this to the C185's and C206's we were flying on floats in salt water. They got treated pre and post float season, and fared well.  Land based mooney, probably get away with a treatment every 2 years or so.

[Piloto]

From my experience on Strikers 44 in PR I do not have a gallon of paint but a Rust Oleum spray can and instead of a box of 12 WD-40 cans box just a couple of cans. And no need to worry about the bilge pump that can cause the boat to sink right at the marina but air pressure in the tires.

Best corrosion prevention is to keep your plane in a hangar. When outside and raining water can make its way into the structure and cause corrosion. Unlike Striker boats were the aluminum structure is much thicker Mooney structure is more fragile and subject to corrosion than the Tuna Tower on the boat.

When on the boat doing maintenance I had a belt with a holster for holding my WD-40 can.

Best anti-corrosion products can be found at West Marine stores   https://www.westmarine.com/

For bonding an filling holes I use Marine Tex https://www.westmarine.com/search?Ntt=white+marine+tex It keeps your boat from sinking or your plane from falling.

José

Edited June 14, 2018 by Piloto

[jaylw314]

39 minutes ago, Piloto said:

When on the boat doing maintenance I had a belt with a holster for holding my WD-40 can.

We need a photo, Jose

[Piloto]

2 hours ago, jaylw314 said:

We need a photo, Jose

Good for climbing into the tuna tower with your WD-40 can for lubricating the wheel and controls and having your coke can drink.

Edited June 14, 2018 by Piloto

[jaylw314]

1 hour ago, Piloto said:

Good for climbing into the tuna tower with your WD-40 can for lubricating the wheel and controls and having your coke can drink.

Hah!  Just make sure you don't get them mixed up!

On second thought, you probably drink a can of WD-40 daily, right?

[Piloto]

3 hours ago, jaylw314 said:

Hah!  Just make sure you don't get them mixed up!

On second thought, you probably drink a can of WD-40 daily, right?

It keeps your joints lubricated and cures your  ED