Wires

[t j]

Get a hard copy of AC 43.13-1B

"Chapter 11. Electrical Systems
ON line here http://www.aeroelectric.com/Referenc...Electrical.pdf

Look through all 12 sections in this chapter. Everything about proper aircraft wiring techniques is in there. You will be surprised at the good information and probably important things you didn't know about wiring an aircraft.

My favorite sections:
Section 10. Service Loop harnesses

Section 11. Clamping

Section 12. Wire Insulation and lacing String Tie
I have been progressively replacing the plastic zip ties in my wiring with wire lacing string. It takes longer to install but is much nicer in my opinion. I can reach behind the panel without drawing blood now.

[DesertFox4]

Jeff- thanks for the tips. Makes perfect sense.

Tom- I appreciate the link.

[jiott]

One thing I found very handy for bundling wires in the longer runs like from the tail cone to the console and the console to the panel was lightweight plastic 1/2" sprinkler pipe (lowest pressure rating like 100 psi I think). I slit the pipe lengthwise to easily get the wire in and out at various points along the run. The slit would close back up and contain the wires quite well. At some points along the run I would put some zip ties around the slit pipe to attach it to the frame and keep the slit closed if needed. I even ran some of my pitot and static tubing inside this pipe. It is really lightweight and gives very good protection to the wires.

[DesertFox4]

Jim, I used that on my model 4 and the 7 SS. Makes running wires from the console to the tail easy. Also great for future wires if needed. Very lightweight.

[Flybyjim]

Thanks, all good info

[efwd]

Awe, perfect timing. Fixing to start putting the plane back together. I need to address some issues. Thanks for the post John. It has drawn out some wisdom that I can use. Thanks Jeff.

[n85ae]

Sorry to add more work, I'm waiting on my fuel pump to come back from the shop, and my exhaust
to get back from the welders. There's no winning ... I'm wondering now after all these years if when
I installed my exhaust whether there was any binding that later led to cracks ...

Seems everything in the plane with an "O-Ring" in it is leaking as well ... Fuel drains, valves, etc. (I only
run Avgas, but this is 16 years since I built it ...

Jeff

[jmodguy]

For what it’s worth, hardware store splices do not belong on an aircraft. See Jeff’s pic above. The coatings on the Tefzel coated wire strands are sensitive to moisture. I have seen entire spools ruined due to moisture penetration of the wire via an unsecured end. You should use environmental splices that have wax sealing plugs on both ends of the insulator.
I was in the Navy as well wiring EP3s for 20 yrs. We used string tie as well as plastic zip ties. Either will work but do cut the zip ties flush with the clamp or you will regret it one day! Do NOT use wax string that is made with bees wax. It is organic and can/will mold.
As a certified IPC/WHMA 620 Instructor, a good reference for terminating wires is the IPC/WHMA 620 manual. This doc defines criteria for Class 1, 2, and 3 interconnect terminations, securing harnesses and many other harness needs. It is not cheap but it will tell you what it should look like when you are done.

[jrevens]

Great points, Jeff! I think I can see the places you’re talking about. There are a lot of crimped connectors/terminals where the wires are secured to neat little arms that come out from the base of the connection points. That may not be very clear in the pictures.

Also, I sure didn’t mean to be as negative about lacing as it seems (even to me) from my comments. I think it’s still the “gold standard”. I was just a little surprised to see how Pilatus did it... even using the very same brand of ties that I like to use. Guess it seemed like a little bit of vindication for my laziness. 😉

[n85ae]

No worries, I got out of the Navy a million years ago. I was an Aviation Electrician's Mate
and worked on Grumman E-2C's, I was the shop QA inspector, so I'm still nitpicky about
wiring.

This is the kind of stuff to avoid. Wires are floating off the crimp, and the wire will vibrate at
the crimp, work harden, and break. I would tie the wires each side of the crimp, and let the crimp
float if anything.


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