Powdercoating

[GAHorn]

So, Tom, I guess this means your shop will provide a basis of approval to apply T-56 bracket powdercoating for C-170 engine mounts then? That's because they are such identical items, serving identical purposes in identical environments, of course. When you can get them to put it in writing that their process is OK for other applications, then I'll believe it.
Tom-"Our Air intake housing is 2400 series aluminum. just like the cases in your C-145" Air intakes are not the sort of critical item we were discussing. And BTW, the engine sump case in a C145/O300 is not aluminum, it's magnesium, not that it means anything. And the aluminum cases used for air intakes (elbows) in the 145,... I'm sure is OK to powdercoat air intake induction parts. Hardly the type problem we've been discussing. Air intakes aren't stressed items, and they don't suffer from heat dissipation problems.
How many T-56 brackets have cracked that you haven't noticed? You'll never know until it lets go. By that time, of course the powdercoating has cracked as well. In a tubular engine mount, we'd sorta like to notice before it gets that far. (BTW, my opinion in this matter is the result of the local DAR who showed me a powdercoated engine mount. It had cracked and failed just subsequent to an annual inspection that had inspected that mount. He convinced me that powdercoating can hide cracks, and he pointed out that it was not an approved process for mounts. I don't think this DAR is foolproof, but it was pretty convincing.) He recommended lacquer on mounts and wheels.

As a matter of interest, there are some new technologies regarding powdercoating that may do away with the heating or "thermosetting" as they call it of the powders. Some new powders are being developed that are cured with UV and/or Infra-Red light that show promise in this area. This would make the process available to those aluminum parts that would be heat damaged.

Also, the Kitfox experimental airplane can be ordered with it's frame predominantly powdercoated....but....they caution you that it is not powdercoated in the corners and at the welds where the kit builder is instructed to paint those areas with ordinary aircraft paints (usually recommending Stits products.) I know you won't believe it, but I've got an opinion as to why.

George - Across from some, but hopefully not cross-ways with friends.

[Tom Downey]

I know we both believe what we see. that is what keeps our opinions as they are.

We inspect each iron bracket we reuse with a ultra sound with the powder on. It has never shown us a crack we can't see. but It points them out faster.

The first year or so we stripped all brackets and inspected with magna flux, and never found any with cracks that we thought were good by visual means. WE believe that if the Iron is cracked it will be seen even when powder coated.

You say " Air intakes aren't stressed items, and they don't suffer from heat dissipation problems. "

For your further info, the T-56 intake is Anti Iced at 650 Degrees with 14th stage compressed air. and Carries the Reduction gear box which weighs over 600 pounds, and the #1 bearing cage that carries the compressor rotor that spins at 13,820.

I do not believe there is any part of a Cessna that disapates heat, or requires strenght that urethane powder can't protect better than paint, when done properly.

I will admit getting the local car type shop to powder coat an aircraft part is not the best method of getting it done. Due to the lack of proper monitoring of heating or type of powder used.

But stating that powder coating is bad, is not true also.

The statements that have been made in this thread is proof that most people do not know what powder coating is, or can do, and that lack of understanding leads to old wives tales that purpetuates into us being regulated, and not being allowed to use the best methods available in maintaining our aicraft.

Victor Aviation is not the only one powder coating aircraft legally. I do think they make too much hype over doing it. They even went thru getting an STC for doing it. When actually it is a minor change and does not require a STC. which to me is hype and sales ability and feel good by the FAA.

What is the difference between powder coating and painting legally?

Wouldn't it be the same as changing the paint on your aircraft that came from Cessna which was lacquer, to Polyurethane?

Doesn't that equal a minor change?

The only thing different in painting and powder coating is the method of curting, because there is a powder that is equal to any paint on the market.

[GAHorn]

Thanks for the input, Tom. My comment regarding air intakes was meant with regard to C145/O300 intake parts. But the reason the air intakes on turbines/jets are anti-iced with hot bleed air is because they don't have a heat dissipation problem. They run too cool in icing conditions and must be de-iced. When that is realized, I feel it only further supports my opinion (that powdercoating retains engine heat.)
Powdercoating's heat retention characteristics would be a plus when trying to keep something from icing up. Piston engines are trying to get rid of the heat.
I don't know of any 170 owners who are likely to pre-flight inspect their engine mounts with ultrasound, and I doubt any IA's are going to remove the mounts at annual to do it either. But if powdercoating techniques have improved to the point that subsurface cracks at welds are visible to the naked eye, then I'd certainly drop my objection to it on welded or stressed parts. It does indeed hold corrosion down.
The next consideration with powdercoating is removal for inspection. It is so durable that the stuff must be bead blasted off to inspect the underlying structure. (This is probably the best way to do it with enamels as well, but the point is that MEK and paint stripper isn't going to do it. A person must have the equipment to inspect powdercoated items that otherwise would be more easily inspected.)

[Mike Smith]

Tom,
It sounds to me like you've made some good points, and George has countered with some valid concerns ... what I see as the real questions now are:

1. How would an average C-170 owner get that powder coating that you have been talking about?

2. Would the obtaining of the powdercoating process be worth the cost to someone who is comparing the cost to the more common methods?

3. Once the powdercoating process has been obtained, would the average C-170 owner be able to do any of the special inspection items you mentioned in your arguments?

**So the overall question really is:
4. At the end of the life of an engine (with its motor mounts), would the average C-170 owner be happier with this powdercoating (including the cost of it) or would the hassle and cost of obtaining/inspecting this powdercoating be prohibitive to the C-170 owner with limited funds?

Sincerely,

[Dave Clark]

I give up? I thought it should be relatively simple. I'm outta here.

[Tom Downey]

For the 170 owner with an engine mount in their hand, all they need to do is call the facility that they would use for powder coating and ask if they would do it in urethane powder, and tell them that you are only after corrosion protection. (they won't pile it on as heavy)

At the cost of poly paint today with the other chemicals we need to finish the job it is cost effective to powder coat. (Think thinner at 65 per gal, atcylist at 45 per qt.)

the inspections at annual need to be no more than the regular visual, looking for cracking, visable heat damage from exhaust, just like any inspection.

We use ultra sound because we use sailors for inspectors, its also faster.

The things I do not like at annual time Is to find that the engine mount gear legs and other steel parts that are rusty, rust makes stress risers in steel parts which can lead to failure.
When these parts are cleaned and treated as need when they are powder coated the rust will be stopped.

Many people can't see the advantages of the system of protection, but in my humble opinion its worth is far more than its bother.
Its only draw back is difficult removal, and like all systems it will fade.
The primary removal method is a bake off process that is very much like a self cleaning oven. But as well as it protects this is a non event for most people. (once it is on it looks great, lasts a long time) There are a couple wet strippers that will remove it but they are messy.

[Tom Downey]

GA says

Thanks for the input, Tom. My comment regarding air intakes was meant with regard to C145/O300 intake parts. But the reason the air intakes on turbines/jets are anti-iced with hot bleed air is because they don't have a heat dissipation problem. They run too cool in icing conditions and must be de-iced. When that is realized, I feel it only further supports my opinion (that powdercoating retains engine heat.)
Powdercoating's heat retention characteristics would be a plus when trying to keep something from icing up. Piston engines are trying to get rid of the heat.

What you fail to realise is we port 650 degree hot air into the intake housing and allow it, and the first stage vane, to be heated from within, unlike adding hot air to the intake air to prevent icing. The powder coating actually aids in heat transfer for anti-icing.

Its actually the reverse to what you think, due to the coating being bonded as well as it is to the surface.

Most of the new efficient furnaces are being coated with a powder coat to increase their ability to transfer heat to a room.

NUWWL (naval under water weapons lab) at Keyport is using powder coating on many torpedo parts to stop corrosion due to the abrasion of loading and unloading the practice torps at sea.

Many of the F/A 18 flight control and engine parts are using powder to protect them, and no special inspection requirement are needed.

Our facility is also evaluating powder on wheel halves to stop corrosion caused failures.

I am trying to get approval for using ceramic powder as a repair for our C-145 oil sumps due to corrosion.
I have 2 soaking in hot oil they have been there 3 months no problems yet. we will see what FSDO says as an authorised repair.

Powder coating is the wave of the future, the more we know about it the more we realise that what we see on our lawn chairs is just the tip of the iceburg.

I would wager in 5 years we will see it being treated like plating, done in a controled inviroment to aviation standards, and it will be no biggy.

I'mm outtahere too, e-mail me with more questions if you like.

[Walker]

It was mentioned by GAHorn that you can beadblast off powdercoating. I have tried and gave up on it and burned it off with a torch. An associate who has a sandblaster that will blow anything to sheds if you wanted to showed me his attempt at removing powdercoating. The results were about the same as mine. How else can you remove it other than a torch? For many parts, if the only way to remove it is with a torch, powdercoating is an irreversable technique. But then again, this may not be such a bad thing as there are way too many old airplanes out there.

[jon s blocker]

You can remove powdercoating with a wire wheel brush and a drill. I have had several things powdercoated and have had very good results.Before I went to powdercoating, I used a coating called Diment Coat, although I don't know if you can get it anymore, (thank you EPA). We put it on our landing gear, (Piper Super Cruiser), and used to land on the beach and fish. This was on the Gulf Coast and the salt water was really harsh. I never had the landing gear rust! I also used it on the motor mounts with great results. Back to the powder coating, if you are concerned about cracks, use the wheel to "buff" it off, then recoat that area. It can be taped off, so you dont have to respray the whole thing.

[wa4jr]

Perhaps I have not seen the new high tech powder coatings, but the ones that I am familiar with are a bit rough or textured to the touch and appearance. I would tend to believe that this textured finish would attract and retain oil and dirt. I like my smooth engine mount tubes where I can just run a rag down them and clean them off. I think I will just stick to the conventional paints. Besides, the casting texture on our cylinders and cases simulate powder coatings good enough for me...but then maybe I'm only thinking of the my powder coated lawn mower handle