My Wooden Airplane
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10/2/2013 - 10/20/2013

Firewall

This is why I chose to delay the closing of the firewall until I was sure that I was done punching holes through it. There are close to 100 holes in it (although most of them are for bolts attaching things to the firewall)! Compare this with what it looked like when built from the plans! Because the firewall is not solid, every hole needs some sort of block to support it, and I didn't know exactly where they were all going to go until now.

Now that all the holes are drilled (and supported), I can finally cover the front side of the firewall with plywood. Those 4 recessed areas are for the "spherical metal grommets" that clamp the control cables as they pass through the firewall (see the next picture below).

With the firewall all closed up, I can install the .018 stainless steel firewall protector, along with those "spherical metal grommets" and some other fittings. Based on some reading I've done, these are the only two true "fireproof" methods for penetrating the firewall. The "spherical metal grommets" are expensive, but allow the cable to pass through the firewall at a wide variety of angles. The other fittings will have pieces of firesleeve material inside and out, acting as both a fire protectant and as a guard against chafing. Apparently, the common practice of using a standard rubber grommet covered by a stainless steel "shield" doesn't hold up very well against a direct flame. Also, I'm going to see if I can consolidate some of those holes for the wires. If so, I'll just cover the unused holes with a flat plate.

Total Time: 42.5 hrs.