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PEX pipe for wing conduit

Gregg Brightwell

Gregg Brightwell

Well Known Member
...I have decided to use pex pipe for my wing conduit, after reading a post by rocketbob. (-7 forum).

I am PLANNING on a NO A/P, VFR aircraft.

I want a heated pitot, landing light/taxi light nav lights/ strobes, (LED I hope)

If I wanted to run NAV/COMM antennas out to the wing tips, can I get all of that in a 1/2" ID Pex pipe? Or would I need to get 3/4"?

I have searched, but can't seem to find that specific scenario.

Thanks,

Gregg
 
Consider PVC

Greg,

You may want to consider 3/4" PVC drain pipe, thin walled, very light (probably lighter than PEX). I assume the PEX will come in a coil and I think it will be a bit unmanageable. Here are a few pics of my install.

aea38a59.jpg


These brackets come from Home Depot, secured with aluminum pull rivets. Added an aluminum washer under the rivet head since the pre-drilled hole in the bracket was a little large.

d4860502.jpg


Put another pull rivet through the bracket to keep the conduit from twisting

f4deb9a5.jpg
 
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3/4" would be better. That's what's in the wings of my Rocket. Just ran an wingtip autopilot servo wire in the -6 I fly and it was tight with 1/2" conduit with several wires running thru it.
 
Not sure I would do the rivet into the conduit thing, leaves the chance open for wires to chafe on the exposed end of the rivet.

Yes, low probability of anything going wrong, but still...............

f4deb9a5.jpg
 
Mike S said:
Not sure I would do the rivet into the conduit thing, leaves the chance open for wires to chafe on the exposed end of the rivet.
Click to expand...

Yeah, good point. Since some of the wiring will be exiting the side wall of the tubing e.g., stall warner, I thought it was essential to to keep the conduit from twisting. That rivet is as the end near the wing-tip, and easy enough to cover with something that would prevent chafing.
 
If you look at what all the tractor trailers are using for air lines, poorly routed, rubbing on frame rails, 125 psi and yet after 27 years of working on this stuff, I have not seen a rub through failure, so that is what I used for my wing conduit. The 3/4" DOT air brake line has a .100" wall with reinforce cross hatch woven fiberglass strand, light weight and cheap.
 
Av8torTom said:
Yeah, good point. Since some of the wiring will be exiting the side wall of the tubing e.g., stall warner, I thought it was essential to to keep the conduit from twisting. That rivet is as the end near the wing-tip, and easy enough to cover with something that would prevent chafing.
Click to expand...

Instead of a rivet, some RTV or proseal between the conduit and the clamp should hold securely and prevent any twisting.
 
Fumes

I didn't want to use PVC conduit for the same reason they don't use PVC insulation on the wires. I dug around on the internet for an hour or so and discovered that both nylon and PVC fumes are quite nasty. PEX fumes aren't near as bad.

Maybe I'm going a bit overboard in worrying about conduit burning. Also, in the wings, it's maybe not as important. I'd rather be safe than sorry.
 
Conduit

Check out the 8 foot clear plastic tube at Lowes , used to protect flouresent light tubes , weighs less than nothing .
Tom
 
Safety

Came across this article summarizing the combustibility and toxicity of PVC. In summary, it is rated as:

1. Difficult to ignite using common sources (752deg F)
2. Will not support combustion
3. Is self extinguishing
4. Major gasses produced are carbon monoxide, carbon dioxide, hydrogen chloride and water
5. Hydrogen chloride is considered Harmful on the Harmful, Toxic, Highly Toxic scale
6. Resistance to ignition and low potential to support flame spread are the most significant properties which contribute to PVC fire safety.
PVC is particularly good in this respect and this is recognized in the UK Building Regulations.
The toxic potency of PVC decomposition products is similar to that of most other materials.

You decide - I'll keep the PVC in my wings.
 
PEX conduit ...

... Is what I used in my wings. Worked great .... Plenty of room for all the wiring mentioned in the OP, inexpensive, and was easy to fasten to the lightning holes with small angle brackets and Adels.
 
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