#FIREWALL BUILDER CLASSIFY EXAMPLE PROFESSIONAL#

It would be difficult to land an airplane with intense heat pouring through the hole where an aluminum cabin heat box used to be.įuel lines are particularly hazardous firewall penetrations. This is something every kit manufacturer and airplane builder should carefully consider. Luckily, Aircraft Spruce now has an all-stainless-steel cabin heat box that should go a long way toward solving this problem. In most cases, an aluminum tube with a 2-inch diameter punches a big hole through the firewall, offering almost no protection from an engine fire. (Don’t forget that unfilled sockets in a cannon plug are like open holes for best results, populate every socket in the connector, even if the pin is unused.)Ĭabin-heat valves are the biggest offenders of firewall integrity on many airplanes. Metallic cannon plug bodies and housings are available, but they’re comparatively heavy and expensive. Realize that penetrations like this mean coming to some sort of compromise, and try to minimize the size and number of these holes. Any serious heat will quickly melt a plastic fitting. Some people use cannon plugs to bring wires through the firewall, and they make for a clean-looking installation, but a large plastic cannon plug is almost as bad as having an open hole in your firewall. These are well suited for running a fuel line through a firewall. This is a steel AN833-6 bulkhead 90° fitting with an AN924-6 nut and an AN960-916 washer. This is not the lowest-cost solution, but it is the safest.

#FIREWALL BUILDER CLASSIFY EXAMPLE PROFESSIONAL#

The steel ones will last as long as the rest of the firewall in a fire and make for a neat, professional installation. An Eyeball Firewall Assembly, available from Aircraft Spruce & Specialty and other vendors, makes a tight seal around any cable penetration, even one at an angle of up to 50°. Using a 2000° F fire-rated sealant will help, but there is an even better solution. That rubber grommet will last about 30 seconds when exposed to direct flames, as will the red RTV, which is only rated to 500° F for continuous exposure. This may get you through your initial airworthiness inspection, but if a fire ever got going in the area of that penetration, you will have some pretty toasty feet in short order. Some airplanes will run all of these cables together and push them through one hole with a rubber grommet, goop it up with red RTV and call it good. If you have a carburetor, you can add a carburetor heat cable to that list. There are, however, better and worse ways to go about penetrating the firewall while still maintaining its integrity.Īny airplane with a constant-speed prop will have at least three control cables penetrating the firewall: throttle, prop and mixture. It doesn’t make much sense to fabricate a nice firewall and then punch a bunch of holes in it, but that is what you have to do to get wires, control cables and cabin heat from one side of the firewall to the other. Maintaining the Integrity of the Firewall

Firewall builder classify example