Firewall fail.

5 hours.

Yesterday, I should have stayed in bed. It was that bad. I started out the day by attempting to mount the RDAC (engine monitor module) on the firewall. I did this by drilling out one rivet in the F-601L stiffener along the top of the firewall, then match-drilling the rest of the holes. Would have been a great plan, except when I was drilling the second hole in the firewall and stiffener, something moved and I put the hole about 3/32 of an inch below where it was supposed to go. Boom, violated edge distance. I have an email in to Van’s tech support to find out whether I’m going to have to replace that stiffener, which would suck like nothing has ever sucked before. It would involve removing the engine mount and the landing gear. The other possibility, since I’m not really placing a load on the stiffener with the 5-ounce RDAC, is that they’ll tell me to “build on.” If that happens, I just have a slightly crooked RDAC, but otherwise it’s fine. So I’m kind of freaking out about that, and really hoping I haven’t bought myself a ton of work with this one stupid mistake.

Then it started to get better: The LA public library emailed and said my copy of William Gibson’s ‘Zero History’ was available for pickup, so Shelley and I rode our bikes down there to get it. But on the way home I almost got run over by an idiot backing out of the car wash. What does this have to do with airplane building? Not much, other than it’s difficult to work on critical things in a state of elevated stress. But I needed a win of some kind, so I decided it was time to mount the heated pitot tube in the wing. Of course, that ballooned into wing wiring.

This pic doesn’t show the tubes, but I originally had the AoA and pitot lines running through the two grommets in the rib in the bottom of the frame.

But it’s a couple of years later, and I now know a lot more about EM interference than I did back then, as well as what equipment I’ll have on board. I pretty much rewired the whole thing. First thing I did was pull out all the wires and cut a section in the PVC conduit to allow the pitot heat wires and AoA tube an exit to mid-wing. I rounded off the edges of the PVC to mitigate chafing, then ran AoA tube, NAV antenna wire, pitot heat, landing light, and position light wires down the conduit, breaking out the pitot heat wires and the AoA tube, while sending the rest down to the wingtip. The strobe cable I ran through one of the grommets from wing root to wingtip, which will help isolate the strobe pulses from the NAV antenna. Supposedly RG400 cable keeps this from happening, but I’m going to be making a lot of connections at the wing root (building in the guest house, remember?), so I want to keep the strobe cable and the antenna as separated as possible. Unfortunately, I can’t close the deal, because I need two more 1 1/16″ Adel clamps for the cut ends of the conduit, otherwise they’ll vibrate against the ribs. Those should show up from ACS in a couple of days, but it really irks me to leave things unfinished because I don’t have supplies. It makes more to double check later.

The other wing got the same treatment, but I’d already cut a break in that conduit to allow for autopilot wiring. I still ran the strobe cable through the grommets near the spar, because I’m not terribly interested in having the strobes make the autopilot twitch. Also, depending on the performance of the Archer NAV antenna, I might put another one in the right wing for a second NAV radio at some point.

After all that, I didn’t get the pitot heat module actually mounted. That’s next.

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