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Wire Routing Through Ribs

rockitdoc

Well Known Member
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I usually rout wires through ribs using snap bushings. But, sometimes bits come pre-terminated, as is the case with the Dynon pitot tube and heater control. So, I just routed the wires through the lightening hole in the rib with 3M mounts in strategic points to keep the wires away from sharp edges.

Pitot Plumbing at Mast.jpg

Pitot Heater Control Wiring.jpg

I am not completely satisfied with this 'solution', and am wondering if there is a better way without cutting off the terminals and routing through bushings. I'll do that, if not, but one of the terminals in this case is a micro molex, which I hate to have to reassemble with my micro molex skills.
 
Or, mount the pitot heat control box one bay to the left (same bay as the pitot). Add a couple of plate nuts to the box mounting tabs, then mount via a #6 screw through the bell crank rib. This way you move all this stuff out of the bell crank bay (and you really don’t want this wire mess near the bell crank).

On final install tidy up the wires with zip ties to the wire bundle going through the ribs.

The wire anchor stick ons alway fail, and usually in very short order.

Carl
 
Or, mount the pitot heat control box one bay to the left (same bay as the pitot). Add a couple of plate nuts to the box mounting tabs, then mount via a #6 screw through the bell crank rib. This way you move all this stuff out of the bell crank bay (and you really don’t want this wire mess near the bell crank).

On final install tidy up the wires with zip ties to the wire bundle going through the ribs.

The wire anchor stick ons alway fail, and usually in very short order.

Carl

I considered that because of all the potential congestion in the bell crank bay. But, the bay the pitot is in does not have an inspection access panel, it's in the bell crank bay.
 
I considered that because of all the potential congestion in the bell crank bay. But, the bay the pitot is in does not have an inspection access panel, it's in the bell crank bay.

Don’t need one, everything you need to do you can reach in via the lighting hole.

Carl
 
Don’t need one, everything you need to do you can reach in via the lighting hole.

Carl

Hmm. Well, I should have waited to hear that. I didn't think that would be adequate so I relocated the heater control to the bay inboard of the pitot. This bay has an inspection door, as well. This solves the wiring congestion in the bell crank bay, but I am still left with getting the pitot wiring through the rib. I may just have to fabricate an 'extended' Adel clamp of some kind.

Pitot Heater COntrol Inboard mount.jpg
 
You can use the lightening hole by adding an L-shaped bracket riveted to the rib such that it is not on the side with the protruding lightening hole flange. Attach an Adel clamp to this L-bracket.

As for the wonderful 3M stick-on devices... the only way I trust them is when they are attached using epoxy. I've seen far, far too many of them come un-stuck over time. Grumman used them to run wires in the tail section of their AA5-series airplanes (some AA1's too) and they pop off and take the brown primer paint with them sometimes, too. Abrade the area of contact, clean it well, and attach the stick-on device with epoxy - they will never come off if you've done the surface prep correctly.
 
Finally Satisfied - Thanks

So, here's what I finally came up with and I am happy: No potential wire interference with hardware, no 3M stickies, and no rib chafing. Thanks for all the input. As usual, you saved me a sleepless night or three.

Pitot Heater Wire Routing Wide.jpg

Pitot Heater Final Wire Routing Close.jpg

I am sorry to hear about the 3M stickies coming loose over time. I have them in some places that will require finding a partner with the yoga skills I lack and the willingness to crawl under my panel. Hmm. Sounds like some recon is required!
 
I am sorry to hear about the 3M stickies coming loose over time. I have them in some places that will require finding a partner with the yoga skills I lack and the willingness to crawl under my panel. Hmm. Sounds like some recon is required!

My experience is the "stock ones" will come loose. I've successfully removed the adhesive tape and reattached them with shoe goo, so if you're gonna use 'em, that might be a longer lasting approach.
 
I used this M22529/2 grommet edging in areas where I was worried about wires encountering metal edges. It’s pretty expensive but I think a combination of this and anti-chafe sleeving for the wires would protect them well.
 
Stand-offs

I use standoffs for mounting through lightening holes that rivet to the rib and have a threaded body. I also have nut-plates that are made with a 90 degree bent receptacle in the event there is not a beaded edge around the hole. I obtained them through various airliner rebuilds and maintenance, but they are available elsewhere I'm certain. Makes for a clean secure mounting for wires and tubing. Airliners are full of them.
 

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I going to do this job in a few months.

I am thinking about 3D printing a loop holder that with go on the lightning hole in the proper orientation.

A print using PTEG or ASA (ABS) should be fine.

Then the only questions are how far off the lightning hole should it hold the tubes/wires; and how to attach the holder to the ribs (screw or bolt with nut)

Max
 
I went with the bay outboard of the bell crank. Then I went a little crazy and built a service panel.



 
Here is how I made my installation.
 

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You guys with your airplanes under construction have it easy. :)

Mine is a retrofit, and while I did end up removing the fuel tank to do the heated pitot/AoA plumbing OAT wire routing, the skins were already on my wing.

I decided to mount the controller and the OAT to the inspection plate itself, and put molex connectors on both the controller harness and the OAT wires. This was much easier and accessible for me since I was working in a very confined space.

Looking back, I could have put the OAT in another place but I had already committed so there you go. It'll work. If I have to remove the inspection plate it's a simple matter to disconnect the molexes and the whole thing will come out cleanly.

One of those learn-as-I-go moments.
 
Hi Vinzer,

Working on an RV-10 as well and I'm on the step where I need to install the snap bushings into the ribs.

Can I ask what size holes and which snap bushings you used for the electrical routing and the pitot tube routing in your pics?

We haven't decided between Garmin and Dynon yet, but I like your approach with this.

Thanks,

Charles
 
Hi Vinzer,

Working on an RV-10 as well and I'm on the step where I need to install the snap bushings into the ribs.

Can I ask what size holes and which snap bushings you used for the electrical routing and the pitot tube routing in your pics?

We haven't decided between Garmin and Dynon yet, but I like your approach with this.

Thanks,

Charles

Hi Charles,

I went with rubber bushings for the holes instead of plastic ones for electrical wiring. The size of the holes are 3/4" for wiring and 5/8" for pitot/AOA plumbing. Hope this info helps.
Vlad
 
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