Conduit for wiring in wings

Bcone1381

Bcone1381

Finished Patrol
I am wondering what builders are using for tubing to house the electrical wiring as it passes thru the wing.
 
Ooo, PEX is a good idea. I was considering some Nylaflow but I hadn't looked if it was available in larger diameters. Browsing McMaster though it looks like they have some thin-walled (1/32") nylon tube for under $1/ft for 1/2" OD. Might go that route, I like the thinner wall compared to PEX or PVC readily available locally.
 
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The builder of my wings used thin wall sprinkler pipe. I’m not to thrilled about it but it would have been a pain to replace.
 
I have seen some 1/4" PEX. Might be all you need (or me) for 3 or 4 20 ga wires. Actually I can't remember if it was called PEX, but it was in the plumbing section of Home Despot.
 
I also used pex from home depot they also had some really nice fittings that allowed easy attachment every few ribs
 
Dennis and I picked up some tubing from the lawn sprinkler department in Home Depot, or maybe it was Jerry's. ( We have those in Oregon). It came in a 50ft roll and very cheap. We tie wrapped it to the rib holes with extra protection for the sharp edge. It just didn't seem right to let it lay there and possibly chafe on the metal. Was NOT easy to do though. You'll want to get somebody who has small arms and flexible fingers, and still it's not easy!!
 

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No conduit. Wire bundle properly identified and tied off at rib locations. Make sure your conduit is not flammable. It passes right by the fuel system. Boeing doesn't use conduit that I'm aware of, that good enough for me. Plus if it's not there it doesn't weigh anything.
Just my .02.
Gerry
Patrol #30
 
Whatever you do, run some thin nylon cord (a piece a little longer than the wire run) along with the wiring, and tie it off at both ends. That way, if you ever need to run another wire through the wing, it will be easy to do so. You never know what changes might occur that would lead you to want to have just one or two more wires at the wingtip... I would do this even if I had no plans to install position lights. The next owner might want them...
 
I used the automotive type corrugated tubing that is split down the side. The solid tubing seems like a nice, neat installation for wires that go from root to tip, but not so much for a harness that has wires branching off for things like pitot heat, landing lights, autopilot servos, etc. The split tubing makes that easy, just wrap some electrical tape around it on either side of where a wire branches off so it won't pull out, plus there are several sizes so where you have wires branching off you can go to a smaller size for those. And I second Jim's recommendation to run string or something to pull new wires later for expansion. I guess with a solid tube conduit you could put it in now and push a wire bundle through it later, can't do that with the split tubing that I used.
 
Weight is a factor for me, as is the ability to add wires in the future. A solid tube will accommodate adding wires in the future. I have no experience, but using a vacuum or air pressure to blow/suck a thread tied to a cotton ball thru a tube is one way. I like adding an extra piece of nylon too forpulling future wires thru. I appreciate the PEX suggestions, but that seems heavy. Hummmmm. Vans corrugated tubing or no tubing. I dont know yet.
 
Someone of VAF (I think and A&P) suggested running wires AFTER closing the wings. That way there is no way you could do it in such a manner that you couldn't get to it to fix it later.
 
"I used the automotive type corrugated tubing that is split down the side. The solid tubing seems like a nice, neat installation for wires that go from root to tip, but not so much for a harness that has wires branching off for things like pitot heat, landing lights, autopilot servos, etc."

For wiring that didn't go to the wingtip, I used a soldering iron to melt holes in the tubing. In my case that was wiring for the two fuel transfer pumps, roll servo and pitot heat.
 
I'm not sure why everyone seems to want to enclose their wiring. What's wrong with using plastic bushings and tie wraps to make a loom? I just have an issue with hiding wiring for ever more so it can't be inspected.
 
Just my 2 cents worth, but aren't the most likely "wear points" going to be precisely where the bushings and tie-wraps hold the wiring in place? And it is very difficult to inspect those points without access from multiple directions. With a "free run" of wire through tubing, it's only the ends of the wire that are likely to wear from vibration, etc., and those are pretty easy to inspect when you remove a wingtip, pull the pitot tube mount, etc.
 
After a few years of deliberation, I ended up with the Vans corrugated tubing running through the jig pin holes of the nose ribs (enlarged) with plastic bushings. This way there is no metal hardware (weight). If you were installing this in a quick build wing without access to every nose ribs, you may need a more rigid tubing.

If I'm unhappy with the completed weight of the airplane, it would be easy to remove the tubing. 1545483328908853604977.jpg ​​​​​​
The total weight of the tubing (28 ft) is 0.75 lb and the total weight of the bushings minus the amount of aluminum I removed to install them is 0.13 lb for a total install weight of 0.88 lb.
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geraldmorrissey said:
Over the years I participated in about 20 company wide weight reduction contests for new aircraft. .88 lbs would have won many of them. That a lot of steak knifes.
Gerry
Patrol #30 Wings
Click to expand...

Ya theres a reason Bob's bearhawk is lighter than anyone else. Aside from the no electrical system.

We took a small cutoff wheel to a friend's plane and cut every bolt we could find to 1 thread showing. Weighed the pieces afterwards and it was just over 6lbs.
 
Another way to attach the corrugated type conduit is to add some brackets with a slotted hole that fits the OD of the small diameter of the conduit corrugation:
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While access to the leading edge ribs in the QB wings is limited, a simple fixture that indexes of the lightening hole and spar face enables drilling of the mounting holes working through the spar web holes without too much difficulty:
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Mounting a clip on every other rib:
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After all the brackets are riveted in place, the conduit snaps into the brackets:
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I didn’t install the brackets on the end ribs, figuring that I might want locate them in a different place depending on how the wire routing goes in the fuselage and wing tip.
I hope this works out. I think it doesn’t add too much weight, and doesn’t have any clamps or tie wraps…
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After going back and forth I decided options and simplicity were my priorities, so I went with PEX tubing through bored out jig holes. It's readily available, cheap and smooth enough to push a wire through. It came in at 1-1/2 lbs total for both wings, less material removed from the ribs and no hardware. IMG_20221127_131853728.jpg
 
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