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How to place remote boxes on subpanel

Flyer2017

Active Member
I'm changing my panel from round gauges to two AFS EFIS with an Avidyne 540 and remote com panel. Trying to figure out how to arrange all the boxes on the subpanel and ribs. Looking for pictures of how others have done it. The 540 projects thru the subpanel which takes up a lot of available space for other boxes. Any pictures or referrals to builders logs would be helpful. thanks
 
I installed an AFS panel in my RV-7. Here are some pictures of the panel and how I did the sub panel. Let me know if you have any questions about what I did.
 

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I'm just getting to this point on my build. I'm using a Garmin G3x system so its different than your install, but similar problem. The G3x has lots of little boxes that need to be mounted somewhere. I'm still trying to figure out where for most of them.

You can use the sides of the forward ribs as well as the sub-panel. My sub-panel like yours has a big hole in it to all for my GNS-430 so the center isn't available. Right now I have a fuse block mounted on one of the available sides. The forward section of the ribs are fairly wide so they worked for mounting 2 of my boxes. These will be difficult to get to once the forward skin is installed so I plan to use hex head screws and nut plates to make it a little easier to remove install. I allowed some room at the forward end so that I could get a tool and my hand in there for install/removal. The pic shown is just a test fit.

I'll probably need to make one or more shelves of some sort under the sub-panel area. The bottom of the ribs in the center, forward of my sub-panel cutout look to be a good option. I'm trying to make sure that I have enough access though. I may need to test fit my radio stack before I can figure that out.
 

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Shelves

I build a row of shelves across the aft side of the panel forward of the instrument panel. Held all the Dynon boxes and then some. Decent access behind the panel.
 

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Someday….. somehow…. You will have to remove these items for repair. Use nut plates and caps crews or you will be faced with a nearly impossible task of trying to remove and replace them!!
 
I "borrowed" an idea from another builder and made a flat, removable shelf between the subpanel and firewall:



It held most of the "goodies" that don't need to stick out of the panel:

 
I have worked on lots of planes where the builder installed remote boxes behind the panel that were almost impossible to access because they didn't consider the skin that was going to be installed over them.
When installing stuff behind the panel, make sure you allow for future maintenance. This would include being able to remove the boxes as well as access the wiring. If you don't, you may regret it sooner than you think.
 
Hinged panels

My boxes are not installed but I fabricated mock ups of everything. After seeing how much real estate was used, I fabricated two panels from the instrument panel to the sub panel. They are hinged fore and aft so they can swing either way or be removed simply by pulling hinge pins. Really makes the instrument panel solid too.
 
I was looking for an area to install a shelf similar to what Ryan did. There seems to be a couple of complications in my build. First the slider ribs are not rectangular so it wouldn't be quite as nice and large of and area. Second I have a bunch of avionics that protrude though my subpanel in the center. It may still be possible for a smaller shelf in that area though.

The other option seems to be placing a shelf or two behind the G3x units. I think I may need to put some more stuff together to see how all of this might fit.
 
I added my GEA24 to the forward ribs. I think I'll put the GDL-52R on a shelf behind the PFD. That seems like a good location.

I'm wondering everyone's experience with installing the access panels on the forward top skin aft of the firewall? On the one hand they could be convenient, on the other hand if they don't seal well they could end up being a real annoyance.
 

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I have round access covers and a friend has rectangular. Mine do not leak, nor do his. A seal was made by taking red gasket silicone cement and making a continued "S" line all the way around the fraying flange of the lid (staying to the inside of the screw holes), then lubricating the corresponding flange area with light spray lubricant, then putting the cover on and lightly tightening the screws.
 
access

Make sure you have access to all the boxes to be removed once top skin is on and make sure you have room for connectors and wire routing. It gets pretty tight. I used Allen screws to mount the boxes because they dont strip out and they are easier to remove when they are hidden; also easier to reinsert blind.
 
If you don’t have access panels, those boxes will be near impossible to service once the rudder pedals are installed. Especially if you used standard nuts.
 
I'm in the process of installing platenuts and I'll use and hex socket head screws. I wouldn't say they will be impossible to reach, but I realize access panels may be a good idea.
 
If you don’t have access panels, those boxes will be near impossible to service once the rudder pedals are installed. Especially if you used standard nuts.

Wouldn't it be easy to service the boxes by simply removing an EFIS screen or two?
 
Access panels

I just updated my panel with the GNX 375 and added the access panel kit from Vans to my -7. Even though I tried to think through future equipment access and wiring access when I built the plane 13 years ago I do not think I could have accomplished this upgrade without basically pulling the entire panel out (3 section panel setup). The access panels made the upgrade doable and while I was at it I relocated a couple of units to make future servicing even easier.

With current systems like the G3 and Skyview you can access a lot of stuff by removing the large display panels but anything on the backside of the intermediate bulkhead and related wiring is still a real pain to get at and being upside down under the panel with only one arm being really useful is not fun at all.

Not everyone agrees on the subject but I am a convert and the kit is only around $25 with pre-punched holes and all the parts, IMHO money well spent.
YMMV
Figs
 
Not sure if I'm the other builder that Ryan mentioned, but I designed a mounting tray that bridges the tip-up panel mounting ribs and also has a drop-down support from the center subpanel support rib. Details here -

https://mightyrv.com/?p=3790

I didn't really plan on dropping the entire tray for maintenance, it's more about accommodating future panel upgrades. It's not impossible to access those boxes with the rudder pedals installed *if* you use nutplates. I've already had to drop the transponder once for a software upgrade (before I found a local avionics person who could update the box via USB) and although it wasn't super easy, it was very doable. Dropping the G3x units should be easier.

The only problem I encountered was not leaving enough room between the tray stiffener angles and transponder/GTR-20 connector backshells/harnesses. They fit, but not as well as I'd like and if I were doing it over again I'd leave out the center support and put the stiffener angles on the top of the shelf as Ryan did.

HTH

Dave
 
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