Airtech Question

[TJ_Slice]

I have been studying and asking questions about covering with Airtech, and am about to get started today covering an aileron today.

I was reading the Airtech manual one last time, and realized I have a big question (I don't know how I overlooked it). Since it is a Saturday, I thought I would ask here first.

Specifically, I am wondering about prepping the aileron. Under aluminum prep in the Airtech manual, after alodine, the last step states: "After the conversion coating and /or wash primer application the surface must be coated with AirTech’s two component epoxy primer."

Is that for paint only, or should I be priming the aileron before covering too? I haven't seen anyone mention priming before covering.

[jaredyates]

I have not read their book, but if it is anything like Polyfiber, the biggest concern is ensuring that the primer is not going to have a bad interraction with the glue and subsequent chemicals. The glue needs to stick to it, and the chemicals need to not dissolve it. The safest course of action would be to reach out to Airtech and tell them what paint is on the parts, so that they can confirm compatibility. Confidence is high that this will be the case, especially since it is confirmed to be compatible with Polyfiber and Stewarts. Virgil can probably tell you the specs on the factory primer.

[TJ_Slice]

I hate to bug them on a Saturday. If I can't get confirmation here, I'll probably just find something else to do and wait until Monday.

[TJ_Slice]

I bugged him. Virgil confirmed it is OK to glue directly on the Bearhawk green primer.

[alaskabearhawk]

FWIW, that’s what I did and it worked out great. Like Jared said, the glue needs to be compatible with the primer. A 2K primer, once cured, is usually ok. If you have some doubt about any other parts, just give it a test with a swatch of fabric and glue.

[gregc]

Also, don't overlook Airtech's YouTube videos. I learned most of what I know about fabric by watching Robbie and his cousin explain things.

https://www.youtube.com/watch?v=smFsLBApVR0

[TJ_Slice]

I've watched all of them... It's part of the reason I chose Airtech.

[TJ_Slice]

Hypothetical here, but I thought I would ask. I started rib stitching this morning, and it is going well.

However, I have poked myself a couple of times.. nothing huge, but I did draw blood once. I didn't get it on the fabric, but what if I had?

I imagine it will leave a stain no matter how well or fast you get to it.

Would primer and paint be able to completely cover it?

[geraldmorrissey]

Why worry, if it still shows through the paint, consider it a badge of honor. Blood , sweat and tears. Some tape on your fingers will help.

[rkennell]

Cold water will remove most blood stains. At least that is what mom told me.

[geraldmorrissey]

Instead of starting with an aircraft part, why not create a test panel. In A+P school we built a wooden frame about 18" on a side that we covered, shrunk, doped, rib stiched, taped and painted. It was a valuable learning experience before we were turned loose on an actual aircraft part. If you have never covered anything before I highly recommend it. Plus you can hang it on your wall.
Cheers
Gerry
Patrol #30

[TJ_Slice]

I am happy with how it is turning out, but I am also completely OK with removing it all and starting over too. I had decided that this aileron would be my test piece. I do plan on doing that before primer and paint though.

[TJ_Slice]

Lessons learned from covering my first aileron with Airtech:

I followed the Airtech youtube videos for most of it. They do a good job of explaining the process.

It's not nearly as noxious as I thought it was going to be. You don't want to go sniffing it, but I didn't need a respirator either.

The thin/thick mixtures are just a guideline. The reducer evaporates quickly, so you will have to add reducer occasionally to keep the glue at the right consistency.

The reducer ratios can be adjusted depending on temperature and humidity. When applying it to the fabric, it's just there to help the glue penetrate through. You are gluing from the bottom up, not the top down.

The Airtech fabric shrinks nicely. I ended up with a wrinkle I thought would never come out, but I was able to iron it smooth once I turned the heat up to 350F.

Don't be in a hurry.. Let the glue dry completely before ironing. If you get glue on the iron, it will scorch and leave marks on the fabric especially on edges. I have started cleaning the iron with reducer before I turn it on.

The most challenging parts of the aileron were the ends and hinge gaps. I used tape on the inside corners, and made a template for hinge area out of cardboard. I used that to create a final piece to finish off that area. It was easier to cut that piece into 2 before gluing it in.

For the ends of the ailerons, I did what Erin and Paul show on one of their videos. I glued down from the top first, folded the bottom up to mark the top of the wing to create the airfoil shape. It creates a flap to give a nice finished look on the end.

Rib stitching is not as hard as I thought it would be, I did have to bend a curve in the needle. I don't know how you would be able to do it with a straight one. I followed the Airtech youtube video. I used the fabric wash to remove any wax left over from the stitching

The double cover was slightly different. Instead of gluing the edges and shrinking the whole piece as one, you glue to the ribs, and shrink each bay separately. The shrinking of the 2nd layer was more challenging, because I didn't want to activate the glue underneath. I wasn't able to shrink it well until I turned up the heat. I ironed quickly to try and just shrink the top layer and that worked.

I decided to go with the hole at the trailing edge on the inboard end for a drain hole.

Also, after pulling all the #30 SS rivets for the trailing edge, I bought a pneumatic riveter to do the flaps.