Like a lot of the Alaska folks, I'm blessed to live near the ocean and also near a ton of interesting fresh water for float flying. Driving along the coast into Vancouver today I started to daydream about setting crab traps on a nearby inlet that is a short hop by plane but a lousy long ride by boat.

My plane is a '63 182 on EDO amphibs and I'm told it has never been operated in salt water. Thus far I've said I don't plan to operate on the ocean because of the increased corrosion but I figure I should at least ask those of you that have made this decision before me.

Would you operate on salt water if it wasn't strictly necessary? Assume fresh water lakes nearby for a rinse and a hose at the airport.

Allan

I wouldn’t be afraid to operate in salt water occasionally, if there was some reason to go there. And, yes, I have done so. Wash the airplane frequently, and corrosion proof whatever you can with LPS, Paral Ketone, etc.

MTV

Mine sees the ocean regularly and has for years before I owned it. We've always just hosed it off when we got back home and the issues we've had with corrosion have been very minor, I can't say for sure they're strictly from the salt water either. That said I'm running straight floats as opposed to your amphibs. Living where we do you'll be missing out on a lot of neat stuff if you won't dip your plane in the salt water once in a while.

The Navy tried seaplanes for a few years, seemed to do just fine, day in and day out, operating continuously in the apparently salt water of the ocean. Now how did they pull that off? I was lucky enough to be sent to Corrosion Control School. Now most of the other pilots in my squadron thought it was a shaft for me. Well it has actually turned out to be quite valuable. It seems the secret to salt water operations is prevention and preparation. Yes frequent washing will help, but preparing the aircraft to operate on the salt is paramount.

There are a whole lot of different preparations you can use. Ones you spray inside the structure to coat the interior. You need ones that seep into the seams and lap joints, then the volatiles evaporate leaving a waxy barrier, effectively sealing the joint. There are things to do to moving joints, like bearing surfaces and control cables. There was a locally prepared method to deal with these, paraffin, asphalt and dry cleaning solvent. The paraffin and asphalt dissolve in the dry cleaning solvent. You paint this on the cables and the areas around bearings. The solvent evaporates, leaving a waxy, flexible sealing of these items. It penetrates cables and seals them. It also gives your aircraft that "Dead Englishman" smell, so prevalent in old warbirds. The stuff is gross, but actually works and is cheap.

ACF-50, Bosheild and LPS-3 also do a nice job of coating things like bolt heads and the ferrous parts. They leave a coating behind. Spray all your exterior lap joints and let it penetrate and wipe off the excess. Use a good quality floatplane grease like Green Grease on your wheel bearings, pump more grease after you rinse. Some operators actually coat some of the bolts and strut fitting in the grease.

Cool, so you have done all that, rinse your aircraft well. Repeat frequently. You need to keep up the application of the different preps.

Thanks all.

The plane won't be subjected to continuous salt air exposure like the Navy planes were so I think I can get away with a targeted application.

What are the key areas to treat? I think I can wrap my head around what is necessary for the floats and tail area. What about under the cowling? In the plow phase of takeoff it seems like a lot of water is turned into mist by the prop and that seems like the hardest place to wash/rinse.

I kept a ski boat on the ocean for a couple years and would regulary spray a mist of wd-40 everywhere I could in the engine compartment. It showed signs of salt air exposure, but not badly so.

Are sacrificial anodes a thing on seaplanes? Or on floats?

Or does it not matter since they’re just about all aluminum?

Cam,

On floats I was operating in salt, I mounted sacrificial zincs on the aft bulkhead of each float. The water rudder arms are steel, blades are aluminum, so subject to differential metal corrosion. At least theoretically. Frankly, if everything is properly painted, and you lube and coat with anti corrosive, I doubt they’re needed. Can’t hurt, though.

Par al Ketone is an excellent corrosion preventive. Paint it on and it creates a waxy coating. Mechanics hate the stuff, cause they have to clean it all off to properly inspect.

Lots of folks use ACF 50, but it’s kinda messy if used right.

LPS 3 is almost as good as Par al Ketone on bolt heads and other hardware.

It’s also a good idea to disassemble the float rigging every other season or so, check for corrosion, lube and re assemble. Not that big a deal on straight floats if they come off for winter, a bigger deal for amphibs. This should be done periodically even if you do only fresh water, actually, just not as often.

MTV

I have no float plane experience, but our Ag spraying environment is just as corrosive, if not more. I steam clean the entire plane inside and out, let it dry, then spray every moving part, seam, fuselage cluster, and generally fog everything with CRC SP-400. Anytime I find corrosion between annuals I clean it up then spray a thick layer of it at that spot. Any rust found between annuals is cleaned up and Restore Rust Converter is brushed on. Pretty well everything firewall forward stays oily as radials tend to do, so I don’t do much there, just look closely for cracks or obscure spots for corrosion/rust. All the flying wire attachments and wing attach fittings, gear and attachments, etc. get regular treatment, whether it’s needed or not.

It’s not a perfect method, but my 13k hr, 46 yr old airframe is in pretty good shape considering the wear and tear it goes through on a daily basis. A word of caution: both SP-400 and Restore dry to a brown color. It will look ugly, but is effective.

If your looking to target areas, look where the spray goes after a water run. Yes, the tail feathers, flaps and tracks. The elevators are a place of special need. The balance horns have lead weights screwed to the structure. These cause dissimilar metal corrosion, salt just helps that along. For those of you that may not realize it. Corrosion is an electrochemical reaction. So adding lead, aluminum and an electrolyte (salt water), you just made a battery. The sacrificial anode is the aluminum. So you would liberally spray barrier protection in areas with dissimilar metals. Think bearings, flap rollers.

Zincs are for submerged items that spend time in the water. Your entire float can be thought of as an electrical field. The zincs make it easy for the electrical flow to interact with the water, getting smaller in the process. The current flow leaves on a train formed by zinc ions. Zinc won't do anything for the above surface structure. Zincs are cheap and readily available at places like West Marine. Heat treated components, like the flap track shown in the pic are especially susceptible. The can have accelerated inter-granular corrosion. My personal feeling is most heat treated high strength parts exhibit this after exposure are genetically susceptible due to poor quality of the initial alloy used during manufacture. I see great variation by the batch. Corrosion cells are within the grain structure and you get tiny batteries from poorly mixed alloys. Coat all high strength fixtures, bottom line.

Why you kind of need to do the entire aircraft, is if you don't seal the joints and a small amount gets in. Then some foggy month, while your airplane sits, water turns to salt in your joints. Guess what happens? So it is kind of like birth control, you don't want your partner to be a little pregnant. If you know your aircraft is going to be on water, much less salt and your planning a paint job a bit of extra is a good idea. PRC the lap joints and just about every other joint after priming. It is worth the few hundred extra. Besides, if done properly, the the plane just looks cooler.

We did a lot of heavy maintenance salt water based seaplanes. We maintained and did the overhauls for Seaborne Airlines in St. Croix and my DOM used to be a lead inspector for Chalks out of Miami (left well before they had their issues). So we had a pot of practicable experience in salt water based aircraft. It was easy to see which ones where properly prepared for the environment. The overhaul bill reflected this as well.

BTW, WD-40 is almost useless in prevention. It entirely evaporates, leaving no protective barrier. Use WD-40 after you wash a plane to drive water out of bearings or hinges. You really should lube your bearing before and after a wash. Before, to try to keep water from invading and after, to drive any lucky water out

Dogpilot, thanks for the long and thoughtful reply. I appreciate it.

I'm a believer in ACF-50. I sprayed it all over my 180 and many years later it still weeps through lap joints and collects dust like on the tail cone. Figure that is better than corrosion though.

180Marty wrote:I'm a believer in ACF-50. I sprayed it all over my 180 and many years later it still weeps through lap joints and collects dust like on the tail cone. Figure that is better than corrosion though.

Did you spray it all over the plane and let it penetrate or did you disassemble the plane and spray the inner bits?

I'm trying to figure whether I can do this myself or if I have to find a shop to do it.

albravo wrote:

180Marty wrote:I'm a believer in ACF-50. I sprayed it all over my 180 and many years later it still weeps through lap joints and collects dust like on the tail cone. Figure that is better than corrosion though.

Did you spray it all over the plane and let it penetrate or did you disassemble the plane and spray the inner bits?

I'm trying to figure whether I can do this myself or if I have to find a shop to do it.

We have a long wand that we can get in and do the wings from the tip ends. Then the rest you can do with smaller cans. I would think Rick would hve a setup to spray it with.
It will look dirty all the time as the ACF keeps leaking through the lap joints, but I agree that that is better then corrosion.

Did you spray it all over the plane and let it penetrate or did you disassemble the plane and spray the inner bits?

I did it myself with the gallon jug and a squirter on a three foot hose. Kinda like windex but long hose. I pulled inspection plates and reached into the tail cone etc. Probably used more than their fogger but it did the job.

dogpilot wrote:For those of you that may not realize it. Corrosion is an electrochemical reaction. So adding lead, aluminum and an electrolyte (salt water), you just made a battery. The sacrificial anode is the aluminum. So you would liberally spray barrier protection in areas with dissimilar metals.

Exactly!! That's the most important part of fighting corrosion!! Also noteworthy is removing stainless steel from the equation and we always used PD (aluminum) washers under every bolt. Sure makes a difference!!! I second the CRC SP-400!! Great stuff!!
John