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Wing Conduit Question - Why Not?

First time poster...

I have opened the RV-9 main rib tooling holes closest to the spar to 5/8" according to the wing wiring .pdf. After the 5/8" OD bushings are installed, I think this should accommodate the wiring needs for a day VFR RV-9. The reason for using bushings instead of conduit is I just like the look of a neatly bundled wires...even though nobody will ever see them.

My question is about installing the 3/4" conduit that is also shown in the wing wiring .pdf. I really can't imagine having a need to run additional wires, but if one should ever come up, it seems like it would be a lot easier to add the conduit now instead of trying to drill additional holes in the wing ribs after the wings are closed. Are there any reasons not to install the conduit while the wings are being constructed besides a little more time and money?

I have searched the forums and a lot of you have installed the conduit. But I'm also sure a lot of you haven't.

Thanks,
 
I did the bushings also. No conduit run for Aurora, as it is not part of the mission. It was a tough choice to build in lightness and not let project creep run rampant.
 
conduit

I know I'm in the minority, but I didn't do conduit.

I can see the need for conduit if you are going to rivet on the wingtip. If the tip is removable it shouldn't be a big deal to run a fish down the grommets and pull a wire. A removable tip and a conduit seems like belt and suspenders to me.

Like all things, to each his own.
 
No conduit here. I plan on putting an expandable sleeve (chinese finger) over the wires and running thru the bushings. Plan on putting a dab of RTD on the sleeve at each bushing to keep it in place.
 
I put in the conduit

It eliminates the need for bundle ties to keep the wires routed in a straight line, eliminated the need to deal with the string ties (or tie-wraps)for wire replacemenr if you need to change the wiring for any reason (original wire gauge too small), protect the wire bundle from the tools left inside when you closed up the wing. All that said I have yet to change a wire after 8 years of flying the airplane.

Bob Axsom
 
Why not:

Do the following experiment:

Cut a short piece of that corrugated plastic conduit that Van's sells. Take it outside and set it down on a concrete surface well away from anything flammable. Use a match or a lighter to put a flame to the conduit material for one or two seconds until the conduit ignites. Take a few steps back so that you don't breath the smoke. Stand back and watch.

No conduit for me.
 
I ran conduit...and glad I did, sure makes it easy feeding those wires down. I too used electrical conduit from the aviation conduit isle at Lowes.
 
Try a different "condute"

Do the following experiment:

Cut a short piece of that corrugated plastic conduit that Van's sells. Take it outside and set it down on a concrete surface well away from anything flammable. Use a match or a lighter to put a flame to the conduit material for one or two seconds until the conduit ignites. Take a few steps back so that you don't breath the smoke. Stand back and watch.


What Roee said is true. However if you do the same to black irrigation pipe
(13mm Dripper line) It won't sustain a flame and goes out once you remove the heat source. It is also easier to get a wire down as it is smooth not corrugated.
Cheers

Jim
 
Run Conduit

I think it will make your life a lot easier some day. I used drain PVC tube. It's lighter wall than supply PVC.

aea38a59.jpg


Also used these supports (with pull rivets - put an aluminum washer under the rivet head to spread the load some) from the plumbing supply store:

d4860502.jpg
 
No conduit in wings on mine

I ran one spare 18 ga wire in each wing. I did not want my wires chaffing loosely inside conduit. It did not make sense to me to run tefzel wiring, then enclose them inside something so flammable. Another reason my plane has very little interior. I put everything that one will ever need inside a 5/8" bushing at wing root then reduced down after ap/roll trim wires were dropped off and continued to tip with 3/8". Not impossible to access through bottom insp panels and tip if needed.
 
Aluminum Conduit

I decided to separate my antenna wires from the strobe and resistive load wires. The latter go through snap bushings in the rib holes closest to the spar and are secured to the spar at each inspection panel hole. The antenna wires go through aluminum conduit (using the smallest wall thickness listed in ACS) which is supported by the snap bushings in the ribs in the "alternate holes" in the Van's wing wiring PDF. I didn't like the flammability of the plastic conduits and the thin wall aluminum tubes are light. The main reason I like the rigid aluminum tubing is to guarantee no contact with the control pushrods.
 
I went with the PVC irrigation pipe.
Being smooth, it's easy to pull wire thru, and will be later if I need to redo anything.
I drilled the ribs just aft of the spar, as low as possible. The wire enters the fuse just below and forward of the aeleron push rod holes.
I don't think that was the best spot, the pitot tube is supposed to enter there on the left wing (RV-8). Mighta' painted myself into a corner there.
I "searched" this thread because of what terrye did: separation of antenna wires from stobe and resistive loads (lights)
I bundled all of them together, relying on the coax to shield the NAV signal.
Does anyone have a comment?
Those who have run antenna wire with strobe and landing/position lights, do you have quiet radio?
 
Scott,

I was planning on separating my antenna wires from my landing light and strobe wires but talked to Jeff from Steinair and asked if I needed to use rg-400 for my antennas and he said they strongly recommended it. The RG-400 is double shielded to help prevent any issues with interference. I am using shielded wire for my Nav/stobes and intend to use shielded wire for the radios and head sets. He ran his that way on a RV-6 or 7 and said he has had no problems. I now plan on running them thru the same hole. That is what I remember from our conversation but don't hesitate to call and talk to him if you have questions. They are always very helpful when I call with questions.
 
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For those that have used Home Depot aviation conduit, what did you do at the exit holes (pitot heat, stall warning, A/P servo) to prevent chafing against the plastic tube.
 
Added conduit

The RV7A I purchased two and a half years ago did not use conduit inside the wings. I had to move two magnetometers because they were two close to the comm antenna and install them at my wing tips. To protect that wiring and allow for future changes I ran flexible conduit (Lowes). Trust me, it's a lot easier to do it during construction then post construction. But in all honesty, it wasn't truly difficult to do post construction.

As for running wire through ribbed conduit - a piece of cake. Just get some kite string, a small piece of cotton ball to secure the end of the string to and then shoot it down the conduit using air pressure from your compressor. Take about one second! Then tie the string to your new wire and pull it through.

If your worried about the weight or fire impact of the conduit I suggest you're worrying too much about trivia. So many other things will burn before conduit (i.e. Fuel) and the weight added is only a few ounces. Well worth the chaffing protection it provides.
 
Burning conduit

I have heard this concern mentioned before. I submit that if the conduit in your wings is burning, you 'may' just have other, more serious issues to deal with. If it bothers you., don't do it. I am going to do it because I don't want to have to deal with wire chafing on metal edges.
 
Conduit

Add one more in the conduit group. I also planned it so coax could be separated.
If it means anything, my career was Telecom Management. Pathways are cheap and easy during construction.
 
I guess I was a little unclear in the question. The conduit runs from the wing root to the wingtip. The wingtip lights and perhaps the magnetometer wires will exit at the end of the conduit. My question is about the exit points along the way. Where the wires exit for the stall warning actuator, the A/P servo, the Pitot heat, and perhaps a leading edge mounted landing/taxi light. Do you just drill a hole in the conduit and pull the wires through. Do you put a grommet on that hole; do you just sand it smooth; do you wrap the wires at the exit point in tape or some other anti-chaff material; do you RTV the wires into the hole.:confused:
 
Solder gun drill

I guess I was a little unclear in the question. The conduit runs from the wing root to the wingtip. The wingtip lights and perhaps the magnetometer wires will exit at the end of the conduit. My question is about the exit points along the way. Where the wires exit for the stall warning actuator, the A/P servo, the Pitot heat, and perhaps a leading edge mounted landing/taxi light. Do you just drill a hole in the conduit and pull the wires through. Do you put a grommet on that hole; do you just sand it smooth; do you wrap the wires at the exit point in tape or some other anti-chaff material; do you RTV the wires into the hole.:confused:

I used a small pencil type solder tool to poke a hole. Wires are wrapped with shrink wrap at the exit hole.
 
Conduit in both wings. This is one where I considered the weight worth the ease of mx. Besides, I could personally afford to lose a pound.
 
I would only advise not to allow the wires to lay against the wings skins or other structures other than the bushings. I have seen wire insulation rub through over time due to vibration and cause shorts.
 
Conduit

We did the conduit, not knowing it was flammable. It was a terrible pain to pull through the ribs; if my wife had ever left me it would have been then. We would not do that again.
 
I am glad I have the conduit in my left wing. When I decided to retrofit the AFS AoA with the Dynon pitot probe, pulling the extra plastic line was a matter of minutes.
 
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