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Conduit and wing wire run

msmst25

Well Known Member
I'm doing a SB fuse while waiting for my QB wings to arrive. I'm on page 29-15 and Step 4 instructs to enlarge the wing wire run location in the mid side skins. I have 2 questions:
Is it possible to run conduit in the QB wings?
What size do people recommend for enlarging these holes?

I would like to add conduit if it's possible, so would like to know what size hole to drill for conduit. If it's not possible then what size should I drill?
Thanks for your help.
 
Hi Matt -
It all depends on what kind of wiring you need to pass through there and how you want to “Dress” the hole. I went really simple and just put a 3/4” hole and then used one of the standard plastic grommets.
 
I made an aluminum flanged tube with a short piece of firesleeve. Whatever you use, you'll want a way to seal it up after the wires are in to minimize air intrusion.
 
I don’t recommend conduit from the side of the fuselage to the inboard rib. The run is short enough not to need it, and many put connectors in the wing root area so the wing can come off (as in for paint).

For the wings, plastic cold water pipe from Lowes fits well in the standard rib holes. I run it from the wing root to the bell crank on the right wing (it has the AP roll servo), then another run to the end rib for lights and NAV antenna. On the left wing the run is from the wing root to the bay just past the bell crank (wires and hoses for the heated Pitot/AOA), then another run to the wingtip for lights.

A dab of pro-seal or your favorite silicon sealer, one at the wing root and one at the end rib keep the tube in place.

Carl
 
Possible, but a pain

I seem to remember getting a step drill to make the holes. The step drill had a 1/4” hex drive, and I had a lot of extensions hooked up to get the holes all drilled. The real pain is getting the vans “ribbed” style conduit through the ribs. There isn’t a lot of room to wiggle it through the ribs. Perhaps others had better luck with different style conduit?

Sam
 
I used ribbed conduit

... in my QB wings. After using a step drill with multiple extensions. Yes, a pain! I’ve had to add a wire or two since, so am glad I did it. Don’t forget to leave a pull string in the conduit or there isn’t much reason to use conduit in the first place.
 
... in my QB wings. After using a step drill with multiple extensions. Yes, a pain! I’ve had to add a wire or two since, so am glad I did it. Don’t forget to leave a pull string in the conduit or there isn’t much reason to use conduit in the first place.

Adding a pull string later is very easy. Compressed air can blow a new pull string through quickly.
 
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