Firewall penetrations for heater

18 Feb 2006 Firewall penetrations for heater

I finally got to the point where I can make the firewall penetrations for the heater. The recommended way is to have the hose barbs for the heater penetrate the firewall, and just seal them up with fireproof sealant. Sounds great, but on the RV8 one of the cross braces for the engine mount are at the exact spot where the barbs would come through. So, I had to come up with another solution.
Here are the holes made by the unibit. I had to do a lot of work with a dremel tool to clean up the *very* sharp edges. As someone said, if you even think about your fingers and the firewall at the same time, you will get cut!

The holes from the inside.

Here are the AN fittings. They are from Aircraft Spruce AN848 ELBOW, Hose Bulkhead, 90º and they cost over $30 each! Ouch!

Note the 0.032″ aluminum backing plate.

Here’s what it looks like on the engine side of the firewall.

The hoses are slipped on.

Next I need to install the heater and put the hoses on there. I’ll do that after finishing plumbing the fuel return line.