Source: 2023 Q2 Beartracks, Jared Yates
This is the third and final entry in a series about Bearhawk electric systems. The first two covered design and materials, and this one is about bringing it all together, starting with tools. I’ll tell you about some of my favorites, and hope you’ll tell me if you have any that I’ve left out.

Many of the wire-related tools are shaped like pliers. First, we have the flush-cutting side cutters, such as the Yard Store SKU 50195 or Stein Air SKU SAT-006. These are not strong, so don’t use them for anything harder than copper wire, and anything much bigger than 18-gauge is pushing it. They are cheap and I consider them to be consumable. They also work great for zip ties, because you can make a nice clean cut that won’t later remove skin if you are working in the area. My next most-used tool is a nice wire stripper. The Ideal Stripmaster series comes with various dies, such as the P/N 45-097 which covers 16-26 gauge. I use one designed for 10-20 gauge wire, and one designed for 20-30. In my case the plastic coated handles are different colors, but if they weren’t I’d probably paint one so that I could know which was which from a distance. Dies are also available for coax and other applications.
Next up is a ratcheting crimper with interchangeable dies, such as the Klein Tools 3005CR. There are several different variations on this style of crimper. One set of dies works with the color-coded PIDG terminals. I also have a set of dies for coax cables and one for automotive spark plug terminals. This last set comes in handy if you are making up an ignition harness for the P-Mags.
Another well-used tool is also a ratcheting crimper, but one whose dies crimp from four directions. This one is made for d-sub pins. As-delivered, the depth stop is set for standard density pins and sockets. I prefer to start by inserting the stripped wire into the pin, then I rotate the wire to ensure that all strands made it into the connector, then insert the connector into the crimper and crimp. You can procure a different type of machined brass stop that will automatically set the depth for high density pins, or if you don’t mind living dangerously, you can just not insert the HD pins fully to the stop. Insert them until the brass end is even with the outer edge of the die, and crimp. With all of the ratcheting crimpers, be sure to conduct a sturdy pull test once the connector is crimped, to ensure that the wire won’t come out. You might also need a crimper to handle big wires, such as the Stein Air SAT-002. On our first plane I soldered these sizes of connector instead of crimping, but the crimping is much faster.

Speaking of pins, you’ll need some way of removing d-sub pins from their housings. The extraction tools range from fragile plastic, to nickel-plated, to fancy brass tools with the replaceable tips (TE Connectivity 91285-1). The nice one is around $30 from places like Jameco and I wish I had learned about it sooner, because it works so much better than the other alternatives. In the photo above you can see that it comes with a little allen wrench and several tips. The green dot tip works with HD d-sub pins and the red dot tip works with standard pins. If you are wiring a whole panel it may be worth buying some extras of these, because while they seem to be the best, they are still consumable. All of the tips and the allen wrench fit into a hole in the handle, under the red cap.

I also get good utility from a device called a wire spoon (photo left). It allows for adding a single wire to a bundle, and works great for helping get wires through a grommet at the firewall or a bulkhead.


There are several ways to pass through the firewall, with my favorite being a welded stainless part and some fire sleeve. Some folks on the Aeroelectric list talk about finding bathroom fixtures (grab bars) to make these pass-throughs out of, but you can buy airplane-specific versions from the usual suppliers. I used ACS Part# 09-00978. If you’ll be wrapping the wires with fire sleeve inside the stainless tube, be sure to order an oversized tube to allow space for all of that. If you don’t have room or desire to use such a pass through, you can also make or purchase stainless steel shields for the grommets. Details in the Tony Bingelis books show how to use a socket (like from a ratchet set) and a block of wood to form them. Pre-made two-piece shields such as Part# 61-300 from ACS will likely present a better value unless you are just looking for something to do. I always use some type if shield at the firewall, because in the event of a fire in flight, those grommets will be gone in seconds, and you’ll have an unacceptably large hole in the firewall. I also seal the shield, wire, and grommet interfaces with 3M Fire Barrier 2000 caulk. One 11-ounce tube is enough for a few airplanes.



Having the tools ready is important, but there’s no progress without a definitive plan for which wires to connect. My favorite way to keep track of the wiring plan is with a computer spreadsheet. You can achieve similar results with a pencil and paper, but the spreadsheet allows for easy editing, color coding, and cloud storage. If my whole plan was on a physical piece of paper I’d be scared of losing it. I used Microsoft Excel but the no-cost Google Sheets works about the same. At the bottom of each workbook there are tabs for the sheets within the workbook. Each avionics device gets a tab, such as the audio panel, radio, Skyview, etc. I color-code the background of each tab. In my case Garmin is pink, the audio panel is tan, the Icom radio is blue, and the Skyview is gray. I make up a little table with three columns and as many rows as the connector housing has. The first column is the pin number. The second column is a description, and the third column is the destination. I color-code the background fill for the pin number yellow until the wire is done, then I change the fill to green. This helps ensure that all of the wires are done as the project comes to a close.


In the example to the above, each Skyview component has its own table, with the left and right screens being on the left side, the EMS being in the third column. In this case purple pin numbers are not intended to be connected. Use whatever colors you like, or not! If it helps to make a spreadsheet, then do it, and if not, do what works for you. Just be sure to save it, it will come in handy later if you ever need to change or troubleshoot connections. The second and third columns are filled with the color of the wire insulation.
Wire by wire, the harness will begin to come together. I’ve become especially fond of spiral wrap for this early stage. I get the cheap stuff and cut out short 3-4 inch lengths. If I space these every foot or so, it helps hold the bundle together until it’s complete. The final securing is a matter of preference. I’ve tried methods including periodic zip ties (least favorite), wax lacing cord (lightest weight), and higher-quality Fire-Resistant Polyethylene Spiral Wrap. I feel like it is worth the weight penalty to use the spiral wrap, due to the extra protection it affords the wires and ease of making changes in the future. At the moment Skycraft Surplus has some of the good stuff in stock. I use the 1/4’ and 1/2” diameters.
The most important thing about the execution phase of the wiring is to work carefully and with good craftsmanship. I hate having to chase down and troubleshoot an intermittent problem that turns out to be of my own making, either by performing a poor crimp, or connecting something wrong. Pull-test each crimp, check for good strain relief, check and double check pin placement in connector bodies before you apply power to expensive parts.