Wire routing to aft Fuselage

Discussion of aircraft electrical system design, construction, and problems.

Wire routing to aft Fuselage

Postby NWade » Tue Sep 26, 2017 8:35 pm

Hi All,

As I finish up the wiring for my Sonex, I'm trying to decide exactly where and how to route wires that run from behind the panel back to the aft fuselage.

I have 5 sets of wires:
  1. Headset & Microphone jack wires
  2. CAN Bus wires from the iEFIS Lite unit to the SP-6 compass
  3. Wires from the iEFIS Lite unit to the Trig Transponder
  4. Wires from the ELT remote to the ELT unit itself
  5. The Com Antenna Coax

These should probably be run as at least 3 separate bundles (Coax by itself, the iEFIS & ELT wires, and the headset/mic wires). I'm planning on running the Coax on the opposite side of the fuselage from the rest of them, for maximum separation.

I'm torn on exactly where to run the wires past the passengers, though. Should I duck just under the panel and then tuck the wires up under the canopy rail? Or should I take them down and run them aft at seat-pan level? And do I route the wires around the vertical fuselage structural members or drill a hole and use a grommet? This last one has me very torn, since routing the wires around the structural members would intrude a little bit into the passenger area and make them more-susceptible to rubbing & damage; but on the other hand it seems less-wise to add holes to the vertical members which carry the load from the fuselage to the wing-spars.

I've attached a couple of photos to illustrate a couple of options for the wire routing. I'd love comments from folks with flying aircraft, or photos of how you routed your wires through the passenger compartment!

Thanks,

--Noel
Attachments
wire-routing-at-canopy-rail.jpg
wire-routing-at-seatpan.jpg
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Re: Wire routing to aft Fuselage

Postby kevinh » Tue Sep 26, 2017 10:28 pm

I faced a similar choice and I opted for your second photo. Not flying yet but I'm basically happy with it. If it helps, here's a spreadsheet with how I constructed the bundles (see second sheet). I ran the coax for the antenna down the left side (because I put my com antenna on the left just in front of the spar). I ran the other stuff down the right in one bundle, with a portion stopping underseat, a portion continuing aft and the pitot/static/strobe wires ending just before the spar.

https://docs.google.com/spreadsheets/d/ ... sp=sharing
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Re: Wire routing to aft Fuselage

Postby mike.smith » Tue Sep 26, 2017 11:14 pm

Your photo 2 is more or less where I ran mine. I don't have good photos on my Kitlog site, but here are a few:

http://www.mykitlog.com/users/display_l ... 734&row=52
http://www.mykitlog.com/users/display_l ... 200&row=36
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Re: Wire routing to aft Fuselage

Postby Direct C51 » Tue Sep 26, 2017 11:44 pm

I routed my wires around the verticals like in the second photo except I didn't run them along the horizontal piece aft of the verticals. I ran them straight to the top of the aft spar which keeps them about seat level. They are all in a lightweight sleeve that keeps everything tidy. The seat cushion hides it all.
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Re: Wire routing to aft Fuselage

Postby wlarson861 » Tue Sep 26, 2017 11:54 pm

I used a routing path like your 2nd photo. where the wires cross over the spar they are encased in flexible plastic conduit which is under the seat upholstery. The com antenna is foward of the spar through the floor. I would separate the coax from the other wires if it had needed to go aft.
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Re: Wire routing to aft Fuselage

Postby sonex1374 » Wed Sep 27, 2017 9:17 am

Noel,

Another option is to drill a couple holes in the spar tunnel to create a pass-thru for cable bundles. The lower corners of the spar tunnel (near the lower longerons) are well clear of the spar bottoms and are perfect for routing wires. This keeps them under the seat and out of the way. You can see the general area used in the plans to route the brake cables for the trigear models.

Jeff
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Re: Wire routing to aft Fuselage

Postby tonyr » Wed Sep 27, 2017 10:23 pm

sonex1374 wrote:Noel,

Another option is to drill a couple holes in the spar tunnel to create a pass-thru for cable bundles. The lower corners of the spar tunnel (near the lower longerons) are well clear of the spar bottoms and are perfect for routing wires. This keeps them under the seat and out of the way. You can see the general area used in the plans to route the brake cables for the trigear models.

Jeff


I did exactly the above, used a couple of nylon grommets for wire chafe protection in the holes.
I don't have a good photo available but its pretty simple to do, I ran the cables down from the panel along the front vertical angle piece on both sides, through the tunnel and out behind the seats. Looks much neater and doesn't get fouled by passengers and assorted paraphenalia in the cockpit area.

Cheers
Tony
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