DIY firewall penetration

Just finished cutting all of the parts for a DIY throttle/mixture/prop/alternate-air firewall penetration. Do you see any issues with this design before I weld it up and bolt it on? I did double check that the cables will fit through the tubes.





Thanks,
David

Angles - -

That must be a 10. My 7 are located in several different places, and have some pretty sharp angles with the FW. If you knew the angles, the tubes look great. I assume you checked to ensure all the hardware fits through too.

Are you going to fill them with fire barrier 2000?

I would shorted your tubes to about half that length personally. You don't have really sharp angles before or after the firewall, but they do need to bend. What do you plan to do around the cables inside your tubes? There will Ben open space. If your ID is similar to or the same as the hole size in the firewall, what are you gaining with this approach?

Firewall Penetrations

David that is exactly what I did. The only thing I'd recommend is ensure you have them spaced wide enough apart to allow adding the fire sleeve and the band clamps. Mine were pretty tight especially when you're working in there with the engine mounted.
Rick
#40956
Southampton, Ont

Thats creative David. You going to braze the tubes to the bracket, or just seal them in place?

Just weld 'em to the baseplate.

Read here. The subsequent link goes to a hot test:

http://www.vansairforce.com/community/showpost.php?p=1029182&postcount=17

A hybrid approach would be just a little intumescent sealant inside the tube (for a gas tight seal) and clamped firesleeve.

TS Flightlines said:

Thats creative David. You going to braze the tubes to the bracket, or just seal them in place?

Click to expand...

Just to say it out loud, brazing would defeat the purpose of the steel fire protection. Braze melting temp is too low. Weld it.

Consider a slight flare or bead on the firewall side. So to ward off the clamp and firesleeve "walking off" the end due to vibration, etc.

mjb

First of all, thanks for all of the feedback so far!

- Has anyone tried to remove a cable that has been "potted" into a tube using silicone fire barrier? At first glance that sounds tricky, but perhaps there's any easy solution. Maybe something along the lines of threading a thin wire down the tube and using it as a cutter/saw?

- About how much tubing length is required for good fire ingress protection? The tubes above are ~1-1/2" long, but I understand the arguments for shorter. Dan's tested configuration was 1-1/2" long if I remember correctly.

David

Why do you need firesleeve on to of the sealant?

The easy way to cut the sealant inside the tube is to make a half-moon cutter. Split a 6" length of steel tubing, next size smaller as compared to the firewall penetration tube. Sharpen one end. Now just push it in the filled tube as necessary. Might take a few taps with a small hammer if you can't easily reach the location for a healthy hand push.

I had one tube penetration with a bundle of wires in it. The half moon cut the sealant plug out of the tube just fine, but separating the individual wires out of a big sealant plug was a PITA. It went back as previously described, just a bit of sealant at the end to make it gas tight, and a clamped firesleeve wrap.

A single sleeved control cable? No problem.