Powder coating fuselage

nichzimmerman

nichzimmerman

4-Place #1217
Just found kicks, I got a quote for having a 4 place fuselage sand blasted and powder coated. It came out to $1200. I know several kit manufactures offer this option, is there any disadvantage to powder coating vs priming? And for those of you who have primed their fuselage, would you lay $1200 to not have to do it again? I dislike priming so much that I am considering leaving the ailerons and flaps bare aluminum so I dont have to deal with it. Thanks. Nic
 
Powder coating
Pros: tough, durable, pretty, someone else does it
Cons: difficult repairs or mods, heavier, may hide cracks or rust

Re flaps & ailerons, what is climate of ops? Bob recommended for me (northern Minnesota) not to do anything at all to any of my aluminum - Cessna & Piper didn't. I chose to alodine with spot brushing of zinc chromate, primarily at aluminum/steel interfaces.

opinion fwiw
Mark J
 
A good analysis depends in part on the cost of the alternative. I rented a compressor and sand blaster for around $150 if I remember correctly, and it took a few hours not counting the time to go get the equipment and return it. That included the media and diesel. I didn't do the whole fuselage, but just the pieces that I had welded on. If I had to the whole fuselage, both gear legs, tail pieces, and shock struts, I could see it taking a full day at least. Then the painting was a huge hassle. The problem is that it's really hard to not miss spots with the paint because the tubes are round. You have to get the gun inside of the structure to get those sides of the tubes and clusters, and there is a lot of waste, even with a spot-shaped spray pattern. I used an entire quart of primer for the portion of the fuselage that I did, so for a whole fuselage I'd count on two (at around $100 each). Then if you are going to do a top-coat you can add to that, probably around $100 worth of Aerothane, and I don't know about the other options. So I could easily see a material+rental cost above $500, not counting that it is an absolutely miserable and frustrating job.
 
Powder coating can crack as your fuselage flexes. It can get rust underneath the powder coating and you will never notice it. Some manufacturers use it on their tube fuselages, but we stay away from powder coating. Mark
 
Mark-what is the paint color on the fuselages from Avipro? Is the paint on the fuselage two part epoxy?

The paint coverage on my Avipro kit fuselage was of such high quality, I thought it was power coated!!
 
I will absolutely back the advise the Mark Goldberg gives for powder coating. Don't powder coat a fuselage.

From my experience with a race car (4130 steel tubing) that is now seven years old, we primed the frame with PPG DP series primer. It is easy to recoat for repairs and has never shown any tendency to rust. We also have used the same coating for magnesium wheels with excellent results over the same time peroid.

Powder coating looks great but as Mark pointed out; once the surface is compromised, rust will be a big issue.
 
The MIL spec paints we used are mentioned at the top of the Parts page for the 4 place BH for sure. They are the same paints ( epoxy strotium chromate primer & epoxy top coat) that the US Navy uses on our ships at sea. Mark
 
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Actually my experience with powder coating is a little different. Powder coatings in general are more flexible than a standard epoxy or regular paint. I powder coated as a side business for a few years. I would coat aluminum foil and let people play with it. You can bend most coating down to about a 5/8 radius before it starts to crack. Bad part about that is if your frame cracks you may not be able to see the crack upon inspection.


Dan scratch build patrol #243
 
A metal working group I belong to here in Phoenix just had powder coating demo as a club activity.
Now admittedly, we weren't working under the most scientific of conditions, but I can attest to the fact that we bent some .035 steel to what was probably no more than a 5/8" bend radius after coating and could see ever so tiny cracks in the coating, all lined up and spaced very uniformly, running perpendicular to the radius of the bend.
As for myself, I've sorta figured I'd go "old school" and coat the fuse with zinc chromate, or a modern equivalent, it when the time came.
With the ribs, I've seen Aeronca Champs with what appears to be bare aluminum ribs lined up and fastened to their wood wing spars....seems to work well for as old as they are.
FWIW
 
I haven't decided what I'm gong to do yet. I assume everyone knows this but zinc chromate needs a topcoat if used on steel. I want to use a primer that does not require a topcoat becasue I hate painting but I haven't found anything that I'm satisfied with yet.

The powder coat I had done on my raft frames looks great after many trips and much flexing. However, the powder coat on the A-arms of my snowmobile has cracked and flaked off in the areas where it flexes; I don't know the difference between the coatings used. I do like the idea of painting the fuselage white so if a crack occurs it will be easy to spot the rust, that isn't possible with powder coating.
 
Ask any A&P mechanic that has done repairs on a powder-coated fuselage what they would choose. The ones I have talked to here in Alaska are unanimous: stay away from powder coat.
 
Before we started construction we visited CHR where they made the Safari (Baby Belle) helicopter kits. The frames are TIG weld tubing the same as our Bearhawk. We asked what they did for paint. They said when a fuselage was done that they had a work party. They degreased it, scuffed it all down with 3M sanding pads then shot it with Imron urethane. They had done that for years and had no paint issues. We did the same in that we degreased, sanded the whole fuselage, then applied Endura primer & urethane paint. It really sticks & is tough. I agree that I would not powder coat a fuselage as it rusts undetected until the corrosion expands to pop the coating when it finally shows up. My son has a truck bumper installed a year ago that was powder coated that is now a rusty mess. Good primer & paint applied properly with degreasing between all the steps is hard to beat.

As far as painting goes once the fuselage is primered then all the work is done so applying the paint is easy. The fuselage is the foundation for for the fabric and a lot of work so adding $100 worth of paint to ensure the longevity of the the fuselage makes good sense. Topcoat is usually recommended for any coating system & ensures the integrity of the coating.
Glenn
BH727
 
No Title

I just got through painting a Ford F250 with House of Color Urethane paint. I'm not a painter by any means but it came out decent and I've gotten several compliments on it. Urethane paint is supposed to be tough but it's dangerous s_ _t. You have to use a full face mask respirator! Not even a air supplied half mask will cut it! I know this for a fact! When I get to the point were I'm painting a fuselage I'm using urethane.
 

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Mark Goldberg said:
Powder coating can crack as your fuselage flexes. It can get rust underneath the powder coating and you will never notice it. Some manufacturers use it on their tube fuselages, but we stay away from powder coating. Mark
Click to expand...

I know when I was hanging around in the Vans aircraft world, they were powder coating the landing gear legs and I kept hearing stories of cracks in the powder coating and rust underneath. On my RV-6A my main gear legs did the same. Ended up laboriously removing the Powder coat (not easy) and priming and top coating with a paint with a flexing agent in it.
 
Robert440 raises an excellent point about painting safety. Read the MSDS sheets for everything that you use. For example Stewart Systems and others that are waterborne product use the word eco friendly. I read the MSDS sheets for our Stewarts Urethane so we used proper masks & Tyvek coveralls. We built a spray booth and ensured that it had good airflow with complete air change about every 1- 1 1/2 minutes. Inspite of all our precautions I developed a sensitivity to urethane which is not that unusual for painters. Some paints are extremely toxic and may poison through the skin. Not picking on Stewarts as they make an excellent product that we used so I can speak to it with some familiarity. The fabric turned out as smooth & shiny as a car. If you read the MSDS the hardener is an isocyanate the same as conventional urethane and the part A is not as bad but it is not friendly either. It is basically Part A & Part B similar to any other urethane with the exception that it is reduced to a spraying consistency with water. Painting w/o fresh air will create an extremely strong environment and more than can be managed by a mask. Paint with lots of fresh air, use personal protective equipment (PPE) and change the mask cartridges frequently. The life of a filter cartridge is directly proportional to the amount of chemical in the air.
The one part EKOPRIME is relatively easy to live with but still it requires that a painter uses the proper PPE and take the appropriate steps to protect themselves. Those of us that have worked in industry especially in Canada have to take the WHMIS (Workplace Hazardous Material Information Systems courses) and be knowledgeable on MSDS (Material Safety Data Sheets). We should follow this level of safety at home.
One of the eye openers I had was when Imron urethane first came out deacades ago was an article in a hot rod magazine about a fellow that decided to use it on his car. If it is tough enough & durable for transports then it must be good for a hot rod. He took a serious reaction to the product & was sucking for air. He went to the hospital and the emergency doctors said that there was nothing they could do for him except keep him & observe. That scared him as there was no way to know if he was going to improve or perish. My first reaction to urethane it was what I think an asthma attack feels like. Difficult to breathe but luckily it did not last long. I had a second reaction and decide it was not for me. I prep & sand but stay out of the way of painting.

Please do your homework & read the MSDS sheets then take the recommended precautions so that you stay healthy to enjoy your BH when it is finished. Be safe.
View attachment EkoPrime Primer Sealer MSDS.pdf View attachment EkoPoly Part A MSDS 2010-1.pdf View attachment EkoPoly Part B MSDS 2010.pdf
Glenn
BH727
 
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At the Avipro website, it isn't listed for the 4-Place kit, but it says for the Patrol QB kits:

"Spars and all spar parts are alumi-prepped, alodined, and primered with MIL-P-23377E strontium chromate epoxy primer. Wing skin interiors and all ribs are primered with Zinc Chromate. Steel parts in the wings are primered with epoxy primer and top coated with MIL-C-22750D epoxy paint."

James
 
Nearly all dragster chassis are powder coated as is mine. Looks good now as It did in 2009. Not much flexes more than a Dragster chassis and that is why they powder coat them. It will take the abuse and still not crack. Builders claim you can see a crack easier with a powder coat. I also think it's lighter also. This topic is a lot like the tig, mig, gas welding of a structure. PS my chassis is tig welded with very tiny, pretty welds
Beautifully purple powder coated
 
Thanks for the info Glenn, i am set up to sue the stewart system and am at the point where I am ready to sand blast and paint my fuse, I am using the ekopoxie primer and top coat with the ekopoly top coat.
 
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