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Grommets for wire runs

D

ddnebert

Well Known Member
I am in the process of running wires aft for the RV-10 and have it mostly figured out. What types of grommets other builders are using to cushion the passage of the wires through the lightening holes in the mid-section bulkheads? I've seen something called grommet edging from Aircraft Spruce that looks like it has potential. Any suggestions? See image link below for current view without grommets or silicone...

http://rv10.newgeography.net/wire_passthru_rt.jpg
 
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Van's wiring harness plans call for using MS21266-1N. I think I got one in my fuselage kit, but don't have the bag inventory list handy.

-Rob
 
Stein sells a handy set of gromments that come in their own plastic case. Multiple sizes and shapes and easily carried around while you are crawling inside the fuselage.
 
ddnebert said:
I am in the process of running wires aft for the RV-10 and have it mostly figured out. What types of grommets other builders are using to cushion the passage of the wires through the lightening holes in the mid-section bulkheads? I've seen something called grommet edging from Aircraft Spruce that looks like it has potential. Any suggestions? See image link below for current view without grommets or silicone...

wire_passthru_rt.jpg
Click to expand...

What you have here is not good:(

Vibration will cause the wires to chafe through the insulation in time.

And the smoke will be set free.

At this time, you still can rescue it without removing the wires and tube.

You can use the grommet mentioned above, commonly called "Caterpillar Grommet", you can cut a rubber grommet radially and feed it in, or do the same with a snap bushing.

I would suggest you get a bunch of various sizes of snap bushings, and use them any place they will fit. Use caterpillar grommet for any hole that is too big for a snap bushing.

Obviously, my opinion, you might want to wait and see what others say also.

Good luck.
 
I don't think...

f1rocket said:
Stein sells a handy set of gromments that come in their own plastic case. Multiple sizes and shapes and easily carried around while you are crawling inside the fuselage.
Click to expand...

...Stein sells the edging needed for this application. The hole is too large for normal grommets...:)

It is the MS21266 stuff, data sheet with drawing here from GaHco...

http://www.gen-aircraft-hardware.com/images/pdf/ms21266.pdf

The Mil-Spec stuff that Aircraft Spruce sells is to a higher end specification (more $$) - MS22529 - and has a spring metal insert and fingers that give more of a "barb" effect to grip the edge of the metal, and will get into a much tighter radius slot than the "caterpillar" stuff above.

Cut to the exact length, the MS21266 edging will work well in the large size circular holes as shown in the original post.

Note that some of the cheaper commercial versions of the caterpillar edging are made of a cheaper plastic and will not stand up to high temps as well as the real MS21266 stuff. If you get the commercial stuff, go for nylon.
 
or...

You can split some left over conduit or get electrical conduit from your local NAPA, Autozone, Advance Auto Parts, and sleeve the entire bundle and tie wrap it on both ends, or just feed it through all the bulkhead holes to protect the bundle the entire length of the run-I bet that you have more than one hole like that. Cheap stuff-$4.99 for 15ft.

Mike H 9A/8A

http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/partlist_Wire-Conduit-Looming_N3067H_A|GRP2020A__electrical%20conduit___
 
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The pictured hole is big enough, with (so far) a low fill ratio, such that I wouldn't just "gromitize" the hole, but install a small piece of angle on which to mount a cushion clamp to properly hold the wires in the center of the hole.
 
I bought 5 ft of nylon "grommet strip" from Columbia Airmotive in Troutdale, OR for 5 bucks. Works great, I also used it in larger lightening holes in the fwd fuselage of the RV7A.
 
Here are two examples of MS21266 grommet I prefer to use, the same material widely used in aircraft production. It is common practice to sometimes attach it to structure with RTV.

2dajg3p.jpg
 
If you are going to use a large hole, I would recommend using adel clamps. You don't want wires hanging on the edge of a hole like that, even with "alligator grommet".
 
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There is a picture of a similar installation in the Standard Aircraft Handbook for Mechanics and Technicians using Adel clamps. Very ingenious and appeared to be a very secure way to protect various types of runs.

Wrgway
Don Riggs
RV-7
 
I think what Mel was refering to was something like this to hold the wires away from the edge and to prevent any chafing.


RV200505270021_t.jpg


I don't mean to imply that conduit is required, but this was the quickest photo of an adel clamp I could find. (btw, it's off Tim Olson's site)
 
Got the edge grommet

I got the edge grommet today from Columbia Airmotive, 5 feet. $5. Looks like it will work well. Thanks, all, for the tips and ideas!

Doug.
 
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