Rust!!

This morning I was looking over my kit, thinking about what I was going to do next when I noticed an area about four inches wide, near the center of the elevators, where the powdercoat seemed bubbled. Tapping it with my fingernail, it sounded hollow. I chipped at it with my nail and sure enough, the powdercoat came off and revealed RUST! Thick rust! This was not my doing. I guess something was done wrong during the powdercoat process. Not to mention the work I put in attaching the ribs and foam end caps. I received my kit on August 1st, too quickly I think for even the humidity in Miami to have caused this. I'll be emailing Kitfox also, although I don't expect a reply for a few days since they are closed for the holidays. Check your parts carefully in case someone else has this problem you can catch it before you cover anything.

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This third photo is a bit blurry but you can see the extent of the bumps under the powder coat.

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Yikes, bad news indeed. That is simply bad prep on the part of the powdercoater Kitfox is using. Good for you for looking things over carefully and spotting it.

I've seen this happen occasionally with parts from Van's suppliers too, just a bad batch where some employee didn't follow the proper prep procedure. Please keep us posted as to how the remedy goes.

Jorge, Bad news but not an isolated incident. I found similiar occurences of bubbling powdercoat paint on my several parts in my Series 5 kit when I was building it . Whoever did the powdercoat didn't do enough sandblasting before the paint application. Simply put shoddy preparation and I was as shocked as you probably are after spending your good money on the powdercoat option. I ended up buying my own sandblaster and taking the suspect parts down to bare metal then repriming with epoxy prime and repainting them. Hard to find good help these days. Bruce Lina N199CL

This kind of took the wind out of my sails, but I realize now I may be over reacting. John McBean called me this morning and he was very sympathetic to my problem. He has no problem switching out my elevators for new ones, I'm just not looking forward to having to redo the ribs and the end caps. He suggested I check my other flight controls. On the wing lift struts I noticed some "lumpiness" in a couple of areas. I'm going to take them to a local reputable powdercoat company and have them look at them. If they think it may be rust, I'll just have them strip the parts clean and re-coat them. Hopefully I can put this behind me and continue. I unfortunately do not have the fortitude to go places others have gone, such as hiwingflyer on this forum who rebuilt a wrecked airplane. I tend to sometimes overthink things and then make myself paranoid. Thanks all for your support.

jorge, while i sympathize with you for having a new part in this condition i dont think the leading tube on the elavator is that structurally stressed as it has six mounting points and the trailing tubing also braces it. but thats only my uninformed opinion. my guess is that its .035 wall and the rust has weakened that area. tap it lightly with a small ballpeen hammer to see if it deforms. sandblasting takes metal off and will make it thinner. if you decide not to replace it, some metal etch which is a weak acid will eat the rust and nuetralize it. napa or acs has it. then epoxy prime it. tap the spots on the struts with the same hammer. if it is a thick area of powder coat or welding spatter it should take it but if it has rust under it it should flake off. if you take parts to be repowder coated, the lowest person on the food chain at the shop will sandblast your parts clean but likely make the tubing have alot of thin spots. it doesnt take much on thin wall aircraft tubing to do this. if you decide to replace your elavator i used balsa instead of foam on the ends and was happy with the results. if you need piece of mind in making the decision show it to an a&p instead of a powdercoat guy. havent worked on mine for a couple months now.

Jorge,

Yours is definitely not an isolated incident. I had a few sections on my 7 that the powder coat had bubbled a bit...nothing of that size but nevertheless rust. This is actually a common issue with powdercoat and you will find many guys that don't like powdercoat for this reason. Many tube and fabric builders prefer to buy a bare metal kit and sand blast and coat with epoxy primer like the stuff that Polyfiber sells. This would be the best option I think but a ton of extra time and mess! Has anyone ever tried sandblasting an entire fuse in a home shop or garage? It is like going to the beach...you find sand in cracks you didn't now existed for weeks! So if you don't have the facilities, this is best left to a professional shop in my opinion. Now back to your issue...the suspect areas are easy to spot by inspection. When I found the first section on my airplane I took my angle grinder with a scotch brite disc and sanded the rust to bare metal...I then went over the entire structure very carefully and did this to all affected areas (seems like I had 4 or 5 places in my kit which is a 2002 kit). Lastly, I repainted them using the Polyfiber epoxy primer. Surface rust will not be a problem if removed and painted with primer...sand it down, prime it and move on. Just my $.02.

Hi Jorge.
Are these components aluminum or steel?
Looks like, after the paint is removed there is brown rust, this then has to be steel. If the component was aluminum, you should have white rust.

Eric

Steel. 4130 chromoly steel I believe.

I personally have had discussions with our powder coater on this issue. We will be chatting with him again.