Powder coating airframe???

I´ve been talking this over with a professional painter who does the occational paint job on our airfield. After talking to him it dawned on me that powder coating and powder coating is not the same thing:eek:

Basically there are two types of processes going around. These are named thermosets and thermoplastics (hope I spell this right). He maintains that for a fuselage frame, thermosets are absolutly perfect. He says thermosets have some of the same qualities as normal paint, including the showing up of rust through the coat. They would, however, not show up cracks in the structure very well.

Thermoplastics, don´t get anywhere near them for an aircraft application. It will form a layer of, basically, plastic, that will hide everything underneath.

This is just his professional view. I´m sure others have other views. I have not enough knowledge to say what is correct. BUT, if I had a bare frame I´d powder coat with the thermoset process. No questions asked!

I posed this question to a friend who has some good qualifiucations to answer it…
-he’s an aeronautical engineer and owns a firm that makes equipment for the aviation and auto industries
-he’s a licensed aircraft and powerplant mechanic
-has resored a score of award-winning aircraft ranging from Stearmans (pre-war mailplane & several WWII trainers), to a few Super Cubs, a Harvard, Beech Staggerwing, and most recently a Boeing 40.

He says don’t powdercoat for the reason most others have said, it makes detecting cracks almost impossible.

And once powdercoated, he said it makes the part difficult to repair.

He notes it isn’t illegal under FAA rules to powdercoat, but he doesn’t recommend it.

I would think that doing it to a solid (non-tube) piece that gets limited stress but is exposed to the weather may not be a bad idea.
Perhaps brackets or fittings. I had some brackets powdercoated on one of my vintage cars and it holds up well. But there’s a huge difference between a piece like that and a tube airframe….especially in the UK climate where it seems everything corrodes.
On a hangared aircraft in the dry western U.S., itmay not be too bad, but following his advise, I don’t think I’d do it to a Super Cub seaplane that spends its non-flying life tied to a dock.

I had a fuselage powder coated back in 2000, and never had problems, and know of several others done that way. There’s some interesting debates on supercub.org, http://www.supercub.org/phpbb2/viewtopic.php?t=14608&highlight=powder+coating and search for others. And Kimball Enterprises in Florida makes Pitts 12 kits and powder coats all parts, including fuselage frame and apparently engine mounts, and some of thier kits have been flying and doing aerobatics for years. http://www.pittsmodel12.com/index.php Maybe it depends on who does the powder coating.

Powder coating – the worst!

I have exactly the same experience as all those unlucky TVR-owners. But only on a bicycle….The rate of rot was quite amazing, the frame rusted through in 3 years!

No, powdercoatings on outdoor applications were only in vogue for a very short time. The time it takes to get experience.

Don´t!

Jon

Why not find out what the original spec was and do that to it?
If you are considering powder coating, its but a short step to a bit of nice shiny chrome on the engine

Powder coating

Notwithstanding the comments from the learned Forum members, above, I’d suggest that, if you could afford it, it would be a superb finish for a static aircraft steel frame and any other steel component stored outside but not intended for eventual flight.

Remember though that whatever the component is, it has to be able to fit in the special oven to bake the finish. An Auster frame will require a big oven – and, I would wager, a correspondingly higher cost.

It is a superb and durable finish though.

Anon.

I once powder coated a motorcycle frame and encountered a problem with inside threads. These needed to be re-threaded as the powder build-up prevented their proper function. When re-threading them, it was nearly impossible not to crack the coat around the hole, thus exposing the frame, which then had to be painted. So all in all I didn’t gain anything from powder coating and would not recommend it for motorcycle frames.

As for aircraft frames, I agree with the posters above. Its not worth it.

Powder coating was used on TVR car chassis, the sales patter when they were new was that it was the ultimate corrosion protection, now its a real problem with alot of cars suffering severe structural problems. As said earlier, the issue is that when the protective skin is breached moisture gets in and rust starts, with no outward signs, scrape the surface away and the tubes are rotting away. Do a search on TVR chassis corrosion, shows the result.
For a static restoration zinc coating is probably the best bet. Or an etch primer and hammerite.
Richard

Thanks for the info, i had a hunch that it wasn’t suitable but having read all the write ups it seemed like the ideal covering for an auster airframe….

Any tips on what the best finish/ paint would be, it seems like a massive subject with better alternatives avalible straight after you’ve watched the paint dry……..

Thanks again,

Tim.

No no no!

Powder coating- especially on fuselage frame, engine mounts etc is not to be done!! Yes, it gives a nice finish, especially to kitchen appliances, but has no place on your aeroplane.

Part of the problem is that unlike paint or other protective coatings, there is no active corrosion suppressing ingredient such as zinc chromate, and it is insidious as it will not ‘bubble’ like paint will when there is corrosion under the surface. So what looks like a perfectly sound item can be well and truly damaged and non flight-worthy.

Powder coating and related issues.

Powder coating is a really good way of applying colour/protection to a tubular aircraft frame but a couple of things must be kept in mind.

1. Powder coating will allow maximum protection to those places that are really hard to get at with a normal spry gun. I´ve seen places impossible to get at with a spry gun being very well covered with colour in powder coating. Be aware. Powder coating will be heavier than a normal paint job done with a spry gun, but keep in mind that it will protect areas you didn´t know existed with a spry gun.

2. Never, ever, use Powder coating on anything likely to crack like engine mounts. Powder coating will easily hide cracks. Powder coating on engine mounts is a big NO NO.

On the whole, I´d say, use it on your frame. It will be a bit heavier, but a lot better. If you have some cracking issues ( normally not the case with something like an Auster or a Cub), take care. Never use it on your engine mount. So, basically, powder coat it all (if you are prepare for a pound to disappear of your emty weight), but never powder coat the engine mount.

My ten pEEEEEEEEEEEE´sssssssssss worth.

And they are not worth much,

All the best,
Sigurjon

Powder coating which parts to be exact? Skins or frames?

Either way you probably shouldnt do it.

I remember many years ago here in Australia, CASA declared powder coating of engine mounts as illegal. Not because the heat treatment caused damage (it wont cause damage), but because powder coating wont allow of proper inspection of welding joints for any cracks which may occur.

Many inspections require the paint to rubbed back… and powder coated paint is extremly difficult to rub back!

Also powder coating, while looking really nice, once it has a chip which exposes metal, it will allow moisture to enter under the coating and therefore cause rust/ corrorsion which wont be visible until its too late.

Your best checking with whoever your governing body is… CAA/ FAA/ CASA etc for whats legal etc.

Also powder coating adds tremendous weight as opposed to normal painting…