Aircraft Aluminum and Corrosion [Sling TSi Build]

[@Verb130]

As someone that works on boats with fiberglass and aluminum, and is building a fiberglass airplane, I agree with everything you said. In boat construction, we often call 6061 "marine grade" aluminum. I have used 6061 in bilge saltwater applications. I have had bilge parts in 6061 constantly in salt water last structurally 20 to 30 years.

[@TheBaldPilot]

Thanks for sharing your thoughts, and thanks for watching!

[@OneAlphaMike]

Good video. I came to the same conclusion for the same reasons. A few years down the road I'll probably do a Corrosion-X application, especially if I end up spending more time in a coastal area, where there's more salt air. Not too worried about it in my current location.

[@TheBaldPilot]

I feel the same way Mike. Corrosion X makes it nice to go back and treat if the conditions warrant.

[@rickwiggins283]

There are also corrosion specialists out there that use pressure sprayers with very long, thin 'fogging' tips to coat all the internals with Corrosion-X or similar. Can be done every few years for those that want it. Probably not as good as Zinc Chromate, but apparently the spray stuff is getting quite advanced. At Sun-n-Fun and Oshkosh they have 1-hour seminars with more details on this.

[@TheBaldPilot]

Yes I have considered going the Corrosion X route. Would be pretty messy I'm sure!

[@gilbertofauri2135]

Very good information. Thanks

[@TheBaldPilot]

Glad it was helpful!

[@psgflier]

There are bare aluminum airplanes over 70 years old still airworthy and flying that have never been treated with any corrosion proofing. If you're in a dry environment and keep it clean it should last forever. Had a friend with a Cessna 195 bare naked plane still good as new. He spent 4 hours polishing for every hour flying to remove the water spots, but no corrosion. 2024 is prone to corrosion but most is clad with a thin coat of pure aluminum (Alclad) to protect the alloy so , except for scratches, it's stable in most environments. I have a little experience with aluminum and corrosion as I have flying and maintaining float planes in salt water for 40 years and am anal about corrosion proofing. I just spent over a month cleaning up a Cub wing I thought would take a couple of weeks to recover because of a hint of corrosion starting. I wouldn't worry about it if I were in your shoes.

[@JustaPilot1]

You beat to it. I learned that in the Navy. The aircraft were skinned in 2024 T3 Alclad. The pure aluminum develops an Aluminum Oxide layer which is very thin but about as hard as sapphire passivating the surface and stopping any corrosion from happening. That Alclad layer is also why you can polish the skins to a mirror finish.

[@TheBaldPilot]

Good information! Thanks for sharing, and watching!

[@patrikj]

@@JustaPilot1 ​ You can polish 6061, too. You don't see many unpainted Slings, but the Sonex is also made of 6061 and they're often kept bare metal. A good 6061 polish job looks just as nice as Alclad.

[@JustaPilot1]

@@patrikj Never said you couldn't

[@patrikj]

Yeah I'm also skipping any protection. Now, 6061 definitely corrodes. I had a Sonex, which also uses 6061, in Hawaii parked outside and there was definite corrosion. However, it was only cosmetic. If that plane could sit outside in Hawaii for a decade without any significant corrosion on the 6061 parts, I'm not going to worry. The corrosion on the steel parts was a much more critical factor. Plus, corrosion protecting the entire airframe is such a pain. I'd rather have a finished airplane that may have signs of corrosion in a few decades than a corrosion-proof half-finished one...

[@TheBaldPilot]

I hear ya brother!

[@JustaPilot1]

Curious is the airframe skins 2024-T3 Alclad?

[@TheBaldPilot]

No. Everything is 6061-T6. Thanks for watching!

[@ibgarrett]

I always jokingly tell folks if you want to start a fight with pilots is to walk into the pilots bar and take a firm position on corrosion proofing and then duck and run for cover because it'll get to fisticuffs... The other one that's nearly as challenging is to paint before or after first flight...

[@TheBaldPilot]

I' beginning to believe that! Thanks for sharing!

[@JFirn86Q]

Here's why this is not a good idea in my opinion, hope it makes sense. First, most airplanes are indeed made of 2024-T3 but these 2024 sheets come CLADDED with a layer of pure aluminum. This cladding is for the corrosion issues with 2024. So when you see 2024 corroding on an airframe, it is not "oh yeah that's because it's not as good at corrosion", because it indeed has a pure aluminum cladding. It is not 2024 that is corroding, it is the pure aluminum that is breaking down. NOW - pure aluminum is EVEN BETTER at corrosion resistance than 6061-T6. So 6061-T6 is going to corrode faster than your traditional 2024 built aircraft. If you would put a coating of some sort on 2024 clad, then why would you not for 6061? EDIT: Now, if you aren't in a corrosive environment (like Florida or some place like that) - it really isn't a big deal. Won't be an issue anyways.

[@patrikj]

The problem with the Alclad solution is that the cuts/holes/scratches that penetrate the cladding will let corrosion start. My impression is that the serious 2024 corrosion issues aren't the surfaces themselves but the edges and rivet holes which are all potential places for corrosion to start. Once corrosion has started somewhere, it'll just go under the Alclad.

[@TheBaldPilot]

Great input! Thanks for that!

[@JFirn86Q]

@@patrikj Yeah I thought about that, makes sense. However just remember almost all aircraft grade 2024 is "Alclad". Alclad is a trade name when it first came out, but all 2024 is cladded now that I see available for aircraft panels. Also - you still see corrosion in areas that are not pits or fastener areas, just to keep in mind.

[@JFirn86Q]

@@TheBaldPilot No problem, just my 2 cents for what its worth!