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Securing crossing wire bundles?

Steve Crewdog

Well Known Member
Patron
FAA Job Aid Aircraft EWIS Best Practices says that crossing wire bundles should be secured to prevent chafing, AC 43.13-1B doesn't really address it. I've got 2 bundles that cross at 90deg, any thoughts about a good way to secure them? (note: tying and securing is not complete yet, just planning ahead.)


Thanks
 

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easy wire bundle standoff

You can use a short piece (1/4-1/2”) piece of automotive fuel line (1/4” ID) and a tie wrap to tie the bundles together. Run the tie wrap through the hose, around one bundle, back through the hose (opposite direction from the first time) and around the second bundle. Close the tie wrap. Holds the bundles together, separated by the hose. They can’t chafe each other. (Sorry, no photo handy at the moment.)
 
Steve: Wrap the vertical bundle with a piece of teflon sheeting, with a few ties, along it's length, with it extending thru the Adel clamp, or using some 1" teflon tape instead, with string ties at the ends to prevent movement. Then tie the crossing bundle with an "X" stitch to prevent chafing. Takes almost as much time to explain as it does to do it.
 
Thanks Steve, ironically there's not enough room for that without the outside bundle rubbing on the inside of the hull.

Craig: Sounds good, I'm assuming you don't mean Plumbers teflon tape. Won't need to secure it until the almost-ready-to-fly final assembly stage, but that's one less problem to solve now.
 
wire bundle protection

Thanks Steve, ironically there's not enough room for that without the outside bundle rubbing on the inside of the hull.

OK. How about using some spiral wrap tubing (https://www.aircraftspruce.com/catalog/elpages/spiralwrap.php) or split loom wire conduit (https://www.mouser.com/ProductDetail/Panduit/CLT38F-C3?qs=gyp5g9lXdE5y51pAwxr3vg==) around that section where it may rub the hull?

Agreed, you need something between the wires and the fiberglass hull. Fiberglass tends to act like sandpaper when things vibrate against it. Bad, bad, bad. :D

Second thought: use one of the two above wire protection products above, on each wire bundle. Then, tie wrap the two bundles together, without a standoff. Bundles protected from each other and (presumably) from the hull too.
 
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OK. How about using some spiral wrap tubing (https://www.aircraftspruce.com/catalog/elpages/spiralwrap.php) or split loom wire conduit (https://www.mouser.com/ProductDetail/Panduit/CLT38F-C3?qs=gyp5g9lXdE5y51pAwxr3vg==) around that section where it may rub the hull?

Agreed, you need something between the wires and the fiberglass hull. Fiberglass tends to act like sandpaper when things vibrate against it. Bad, bad, bad. :D

Second thought: use one of the two above wire protection products above, on each wire bundle. Then, tie wrap the two bundles together, without a standoff. Bundles protected from each other and (presumably) from the hull too.


Oooo... I like the Mouser stuff. Much gras!
 
For small wire bundles, even easier:

Tie wrap #1 goes around bundle #1. Don't tighten all the way yet.

Tie wrap #2 goes around around bundle #2, and also through tie wrap #1.

Tighten both. Result: Wire bundles that cross but don't touch (at that point anyway).
 
Steve: Nope, not the plumber's stuff. This is very similar to what we use at work, other than ours meets various Mil-Specs.

https://www.amazon.com/Single-Silic...94N9RFXK/ref=pd_lpo_1?pd_rd_i=B094N51XLQ&th=1

For the sheeting, this would probably work, using a two layer wrap:
https://www.amazon.com/Teflon-Sheet...lpcontext&ref_=fplfs&smid=A1VY9XGL0XLSRA&th=1

The reason I suggested the sheet or tape extending thru the one clamp, is that it appears that the bundle will not fill that clamp size and has the potential for movement, which could wear on the wire insulation over time.

If you use split convoluted tubing, make sure when you secure it, that the split is away from the other bundle.
 
F-1 Tape

Two Adels seems the easiest.
Another option...Wrap with F-1 Self Fusing Silicone Tape then Waxed Lashing String to bind them together.
 
Here’s an example of a certified Canadian product - they’ve literally just held them together with a bog standard cable tie, in a figure 8 pattern.
 

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It looks like you are using lacing cord instead of wire ties? - Bravo !! It is much better. If you just tie the two bundles together where they cross you are done. No chafing plate needed. Lacing cord will hold them very secure so that they can not chafe. I usually wrap the lacing coed in an X pattern across both bundles.
 
It looks like you are using lacing cord instead of wire ties? - Bravo !! It is much better. If you just tie the two bundles together where they cross you are done. No chafing plate needed. Lacing cord will hold them very secure so that they can not chafe. I usually wrap the lacing coed in an X pattern across both bundles.

Thank you sir, I also rib-stitched the wings, instead of riveting as called for in the plans.

Almost ready for initial power-up, just waiting on a battery. Later on I will do final trimming and lacing of this group, but not until I know everything is hooked up correctly and working.
 

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