Today was forecasted as the warmest day we’ll have for the rest of January, with the remaining temps in the high 40’s at the warmest. So, besides building my engine this month, I really plan on getting all the electrical stuff that I can do knocked out, plus a few tasks that I can do in a fairly cold shop.
Today was still about cleaning up some panel electronics and getting some tasks crossed off the list. I decided as I started my endeavor to solder up my Pitch Trim power ON/OFF switch for the TCW Safety-Trim system that I would do a video on aircraft electrical wiring that my buddy Dave asked if I might be able to generate. I still have some editing to do on the video, but will get it posted on YouTube in the next day or so.
First off, in my latest Mouser order I just received 2 new mini-toggle switches with flat bat levers (my preference) for switches #11 (Pitch Trim power) and #12 (Heated Pitot Tube on/off). Besides having 2 different brands of switches in the row of switches on my center panel column (see pic below), the switches that I replaced were ON-OFF-ON while these new ones are simply ON-OFF. No need to waste good switch capacity, especially when the switch levers were slightly different.
I started off by wiring the 18 AWG E-Bus lead to one side of the switch, then covered the solder joint with red heat shrink.
I then prepped the supposed two 20 AWG Pitch Trim power wires (as listed in the TCW Safety-Trim manual) for soldering, but then when I went to strip them found out they were actually 22 AWG. No big deal, just a point on how robust Tefzel aircraft wiring is in handling amps and heat.
I then soldered the 2 twisted 22 AWG wires to the remaining post on switch 11. This switch is the “master switch” that provides power to the Pitch Trim system and exists mainly as a safety switch in case there’s a runaway trim situation.
Here’s a shot of switch 11 (code sw011) remounted in the panel mockup with the soldered wires now attached. I’m waiting to terminate the 18 AWG wire with a FastON connector to then mount to the E-Bus until after my next shipment of wire labels arrive.
I’ve circled switch 11 in the pic below in green.
I then pressed forward with my plan to mount both GRT OAT probes forward in the fuselage, specifically in the nose gear wheel well (NB). I removed and then disassembled the GRT Mini-X wiring harness to slip the gray wire into the mix. Nicely, I was able to use the original OAT probe wire off the GRT EIS4000 harness that was already terminated with a D-Sub socket at the Mini-X end.
After I inserted the wire and reassembled the D-Sub back shell on the Mini-X side, I realized I should probably grab a shot of my progress. As I noted above, I’m out of wire labels but had just a long enough piece of blank white wire label heat shrink to hand write the label for this wire…. just so I could get it in and knocked out.
I then terminated the J3 connector side with a D-Sub pin and inserted the wire into the D-Sub connector. Again, below is a pic of the OAT wire addition task complete, with the J3 side D-Sub jack back shell back in place.
I then reinstalled the Mini-X wiring harness, fired up the panel and checked the OAT settings. I set the HXr on Celsius, set the Mini-X to Fahrenheit, then toggled the Mini-X setting to have the OAT show on the PFD page.
As I mentioned above, tomorrow will be more electrical system tasks since it’s still fairly cold for shop work.