Ti and Fiberfrax Firewall Fireproofing Guide

[nilberg]

That looks good. I am currently doing the same on my RV-7. From the pictures it looks like some attachment points are recessed. They look like micro cupcake forms. What is the purpose for those? Did you make them yourself ?

[vernon smith]

I made the offset washers from the soft .010 SS, with a simple press die with a center alignment pin. The pictures pretty well explains the process. I squeeze the die in a bench vise to form the washer. I used 1/8? Fiberfrax and I knew I would get a lot of pillowing if I didn?t do something like this. I glued the frax to the .010? SS with water diluted Elmer?s glue sprayed on with a pump bottle.

[MElstien]

I am planning on putting a sandwich of either Titanium or SS and Fiberfrax on the belly of my RV-10. I have a QB fuselage so the skins are already riveted on. The forward floor ribs of the RV-10 angle out as opposed to straight back. Does the sandwich need to be riveted to the doubled structure of the skin and the floor rib or can I just make a rectangular sandwich and capture it by just riveting through the skin? If I do the later, I would obviously try to capture as many ribs as possible.

If it is recommended not to rivet just to the skin, the shape of the sandwich will be a trapezoid and the seam running front to back will be exposed a bit to the slipstream. Might that cause any potential problems in peel-back?

I am about to put the floorboards in and it would be much easier to put the sandwich in now while I have access to the floor ribs and can easily drill through them.

I will probably go just 18 inches back from the firewall which would cover the fuel pump. According to pictures and accounts of an actual RV-10 fuel fire, the fire damage did not extend that far back.

Thank you in advance for any feedback.

[David Paule]

On all of my belly fasteners that went through the Fiberfrax, I made small .063 aluminum spacers. That way I had a solid Ti-al-al connection all the way through. With the Fiberfrax laid on top, it was easy to locate these spacers, and using an Xacto knife, cut out the Fiberfrax to clear them.

This is on my RV-3B, using 1/16"Fiberfrax and .020 Titanium for the belly overlay. The airframe itself has the original belly skin there per the plans.

On the Ti edges, I stopped the Fiberfrax maybe 1/2" short of the rivet line and riveted the Ti directly to the aluminum belly. Worked out very nicely.

Dave

[DanH]

Michael, offhand I can't think of any reason why the overlay can't be riveted to the belly skin only. Others have done so, for what it's worth. Through the rib flanges is good too. You'll be using a sealant under the edges, so they are effectively glued with no way for the slipstream to raise them.

[MElstien]

Based on the 2 comments, I will use a simple rectangular sandwich starting at the firewall and trailing back. This will require just fastening the sandwich to the belly skin and possibly a few floor ribs.

Thank You