What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Service Loop Pics

SeanB

Well Known Member
Hi everyone!

Getting ready to install wiring and panel. Anyone have pics of your service loops in areas like behind the EFIS and other components in the sub-panel? How much extra wire for the loop and how did you secure them? Did you make the panel loops easier to access and unsecure somehow?

BTW...I'm building a tipper, so will have the advantage of getting behind the primary panel, but I bet other canopy types will benefit from "lack of access" examples.

Thanks for any help.....
 
Here's picture about half way through wiring up my panel. It's a simple EFIS setup in a RV-8 but if you look at the main harness going into the efis you can see the S-shaped bend that allows for some flexibility to the unit. I found that since I had access via an access hatch from behind I didn't need a full length service loop where you could remove the efis from the front. Your setup may be similar as you have access to the rear with the tip-up.

Wrapping up wiring by Andy Karmy, on Flickr
 
My recomendation would be to provide enough service loop to be able to detach the EFIS (or whatever) from the panel and pull it out far enough to easily access the D-Sub mounting screws.

I have lived with too short wiring in one spot on my panel for 5 years. I was painful. 4-40 screws are not easy to find once they bounce. Recently addressed during an EFIS upgrade. :)

I have a tip-up.
 
Last edited:
Full disclosure; not flying yet.

I tried to leave enough harness length to move the entire panel back and down to rest it face-down on the spar. My thought process (for what it's worth) is I'll someday need a stable surface on which to rest the panel while I do maintenance. Unfortunately, in the -7 tipper, in order to tilt the panel face down it must move to the rear so far (because of the panel support ribs) that you can't rest it across the top longerons. So that drove my decision to make the service loops longer. I also have my switches on detachable strips on the bottom of the panel, and I kept those harnesses bundled to the left & right of the panel, before turning forward to the subpanel. I originally tried to run the entire bundle to one side, but the wire runs were getting too long & I didn't want the unneeded weight.

Do everything you can reasonably do, to make future access better. If you've ever worked on a modern car (or just about any airplane), you will be highly motivated to do this. For example, I just changed the alternator on my wife's full size Chrysler product. I had to remove the right front wheel, two fender liners, part of the front air dam, the air conditioner compressor, and one of the idler wheels for the serpentine belt. Yes, that is the recommended procedure, and it's the only way to extract the alternator from the vehicle. Oh, and a standard socket & ratchet won't fit between the accessory end of the engine and the frame.

FWIW,

Charlie

edit: I can also unplug all the avionics harnesses and move the entire panel (except the switch panels) to the bench.
 
Last edited:
Sean,
With my tip up, I can reach both my G3X d-sub pins to remove them. The radio and AP come out from the front. With the screens out, most of the rest of it is accessible. Just make sure the harness allows you to move the screens if you want to change the panel around.

Since my transponder and VP system go between the sub panel and firewall, those may be a good idea to have a bit extra wire so you can place them where you want.

The only things I made a service loop for are things like the servos, lights, pitot heat, and fuel indicators. I have some extra for the stick switches but it is pretty busy in that area so I didn't want to much extra in there.

I think I had the access panels in the foreskin when you were there. If you want the pattern, let me know.

I did my first engine start last week with only a couple squawks. Im getting close!
 
Tell me about it.

4-40 screws are not easy to find once they bounce.
Tell me about it. There must be half-a-dozen 2-56 screws "somewhere" down in my passenger side footwell after removing the faceplate of my Davrton instrument last week. Yes, I could have used more slack on the wiring. BTW, if you ever need any 2-56 x 1/4" FH SS screws, I now have 100 of them at my hanger :rolleyes:
 
Having service loops was a non-negotiable requirement when I redid my panel last winter. 15 years of maintenance, etc., will teach you that...

I built all the avionics harnesses, at least those which are in the panel area, as I was sitting in one or the other seat. I'm able to pull the connectors back something like 6" minimum aft of the panel. I had my solder iron safely on the wing, my heat gun nearby, and everything else I needed right within reach.

In this picture, just at the 10:30 position from the light, you can see a large cushion clamp. All wires for the avionics passed through this central "hub". Meaning, if a single wire needed to go from one item in the radio stack to one directly below it, that wire first went over to the "hub" and then back again. I can unplug connectors from the back of the radio stack and bring them back aft of the panel in the location where the light is. The cables, in this photo, are in an interim state. All were tidied up prior to completion, but ended up in this basic location/configuration. Note that the harnesses which go to the radio stack are not visible in this picture. All the harnesses you see go to units to the left of the radio stack.

T0EXXyIg6AufpMlRiWm-XhiCJlnRnaCxoWicfoGh7Ne5o8TEbLD4b3F6XZI_rJBulJPdu4yp9eKilfGf7b0CO9vWJztsLHmrSuTVJgbGP-3jRb-scEZUGNGtMviPNvOiXGIxQQoPS4Y20SIzN9FRyC8dnHMxJi_Ttwj99o2pu16Ahaplbs6QHlxCM3pGqCl2s1EjJ0O5q_Rihfn8C4F8FTLHTKbt07p1BYFaZUcBylDKKMUPg7OblLb6ahjUDwiN3z0cJKka4NULYcS2sZbWh7ugIQzHI0PEr_tzYtWOXDJvZnVrsZEKdcTBftQjswwQnDd0NlbSHlLw2ZYTCSWFsu7hSPrbOX0GuyTq0KyuljXYh2x_DmEgyqHtqSwhaAjy0GyMPQzpJdgcWk3axs9Af__Ew-lMPzbfyH6kxH8os_wiXAGErz4ZOv0NIgJdOA9f5wpMKipbIXbxMESpAUYkpZQdUnV0_XP50PnfdOo3U7hbbJu6Pw_xh8MEmqqEJB9QUmxFOqdg6D9mp0_b5GyE9x9re4Dz_afQGihIbfHwVR5-jfNYvIRnvV27rRjxwMIH4W-Hsua5BXfcZJv_Rc40mDcWOu849BexqwEjABWfxfJVS4qWL8Zn=w711-h583-no


Here is a picture of the "hub". The clamp was eventually replaced with an appropriately sized one. Here you can see some of the cables heading towards the radio stack to the right.

vHmHzgy0j5nPlemPOuU_ZC7CZ84Ly3-8bBM2kxcoaU21toARCotI7fBlVO3yg3SzqAMN3i1XubExjuUBCUJ6cTSlxtQBYbI9MLJE081__7UMLFPlfcPMwmxmcfXcwBOAzwZpRQ_eS68zYjpr-mdW6aCcvaHzogFcousV0a522tSD9aA6KN3prcuDO0iYVBKSJuBPV_AbvFVnuM_PyIMJvJ6FxltXI0qYix0veDREQJOdgZ0BOpIpSS30WJw1ikANQjNTY3S_65PqlTO-AGOGDV1ei8A7aOF-Lww_4aHbUnHFtxsnJwOtjwx540mH7UhUlz6op4ojQEqGVSMJor1niiwUhjn2lCBdezJTvlEU-GijE-7-0NnMUu6_2ZkJDHXeG8K9G41neNsia0vJM2ffKDLgs0vsYuX4HPjJQMdBnv6mQ37_IZ46Of77_j8pOXMAyDSCj2N-NtwcgvkIRwxNPHwhw30C6rGf94duIOk4mEHGSemDJdCd5EXHqumhcee__2vJEft5o0QBcCVAeDIDM94UFzd-4CynvOLKE-YcGg-QEhNvV6sHnYPXBBjf5zQ_r70qA6vx4GLg_HpGF1KhWGrjDS52bG3Kf2vmCjYIfpCBYV-UtlZ_=w711-h583-no


I perhaps have a 1 or 2 pound weight penalty for these loops, but if you've ever tried getting into connectors that are not accessible, you will agree it is worth it.

Here are alternate links for the pics:

https://lh3.googleusercontent.com/A...OiqpEBuRx1bK39OxJ2_UTepi3Y443A=w1574-h1180-no

https://lh3.googleusercontent.com/o...SIUqgshRUbSzu3d1qeLDG8znlDlMbw=w1574-h1180-no
 
Last edited:
Thanks

Thanks for your feedback everyone. Yes, I want to build in accessibility and ease of use as possible.

Rock...that's great news on the engine start! Congrats! Excited to hear of your eventual first flight.

Alex...you mention pics in your reply, but I don't see them in the post.

More pics of behind the panel will be appreciated if others care to share them.
 
Sean, google pic links seem to be unpredictable... not sure why, but I'm not the only one who sometimes doesn't see them. I know sometimes there is a delay between moving them to public folder vs being view-able, but I did these last night.

Can anyone else see them?
 
On our LSAs, I run the EFIS wires from the main wiring harness trunk, which passes a few inches behind the panel face on the bottom of the panel box, up to the far upper corner of the EFIS cutout. This allows enough extra wire to be able to pull the EFIS out and set it on my knees to undo the connector harness. It probably adds about 8" to the length that you would need if you just ran enough wire to hit the spot where the connector goes. I can snap a pic tomorrow if you want. The Garmin stuff should be arriving today for the panel I'm working on right now. (Or should be if I weren't sitting in front of VAF. Hey, why not, it's been a while!)
 
I added some direct links to the photos in my first post.

They are the exact same link as those embedded in the same post using the "insert image" link, with the only difference being the two numbers which define size (changed in original post).

Maybe someone smarter than I can figure this out...
 
Here's a picture of my RV-3's EFIS harness. The main trunk bundle is a mess right now because it's just held together with temporary zip ties and there are a few other cables laying there, but you can see the general idea. The EFIS wires just flow out from a single area along the bundle and give you enough length to be able to pull the EFIS unit out a good distance. When the screen is installed, the harness just sits behind it in a nice curve.

36922734915_b21626afc6_b.jpg
[/url]2017-08-30_01-43-50 by jabiruchick, on Flickr[/IMG]

36922743015_d14297be70_b.jpg
[/url]2017-08-30_01-44-17 by jabiruchick, on Flickr[/IMG]
 
I added some direct links to the photos in my first post.

They are the exact same link as those embedded in the same post using the "insert image" link, with the only difference being the two numbers which define size (changed in original post).

Maybe someone smarter than I can figure this out...

Your link worked for me. FWIW, I gave up on Google Photos long ago. They don't have BBC code for embedding in forum posts! Now I use Flickr.
 
Just to tag on to the thread, I've got juustttttt a bit of extra wire to use for service loops, these are to the light switches along the bottom of the panel. Don't have much room to secure service loops since they're on the bottom, anyone want to share how they secured theirs?


TIA


20200625_191249.jpg
 
Roll into a loop

Take what you have and roll into a loop about 2" diameter then tie wrap it. It wont go anywhere, and you can also tie it off to an adjacent wire bundle to keep from flapping. I cant post pictures, but I have service loops on everything..standard practice.
 
The lengths of service loops is a judgement call. I only added service loops to the wires where I had to move the instrument to make the connection like the EFIS. On those instruments where I had easy access to attach/remove the wires without moving the instrument I added enough wire to make a comfortable connection, but not a 'service loop' length.

Here is a photo of all of the harness connections as installed prior to connection. As you can see the rearward wires are longer because the screen has to be pulled out and laid face down for easy access to the connectors;



This is an image of all if the engine sensor wires coming into the GEA24. There is no service loop, however there is enough length to allow working on the connector itself (as I had to do since I connected all of the thermocouples reversed) without much drama.

 
Back
Top