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Wiring: Never do this

Michael Burbidge

Well Known Member
When I built my RV9 it was my first experience working on airplanes. At the time I had no idea what kinds of things made maintenance easy vs. hard.

One thing I had no clue about is how hard it would be to work behind and under the panel. It is nearly impossible to get two hands behind the sub panel, so choose very carefully where you put stuff and how you secure wires.

In the process of installing a new comm radio I came up with the following never agains.

1. Never install an Adel clamp, behind the panel, with a nut and screw. That takes two hands to remove. Always install with a nut plate so that it can be removed with one hand. Next time around I won’t even use adel clamps behind the panel.

F3D081A5-E844-4A2D-97B1-4A546ED9D61C.jpg

2. Never put a service loop in an inaccessible location. (I was so proud of this one) If you ever need to add a wire or remove one from such a service loop and you can only get one hand on it, good luck!

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You can see in this picture that there use to be two beautiful service loops. I had to cut the zips on one to add and remove some wires and now it looks like a galaxy that exploded behind my panel. I’ll try to clean this up. Going to be a fun one-handed exercise.

3. Never put things like regulators and ground blocks up high on the back side of the firewall. They are both inaccessible in my 9.

To be fair, it would serve me well to install the new Vans approved access panels. But So far I cannot bring myself to cut into my beautifully painted airplane. If I ever have to replace the regulator that might provide the needed motivation.

Cheers,
Michael
 
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Good advice here.

I read a lot of posts about what to "finish" before closing up this skin or that. When I see them I try to get the builder to think about what they will do when they need access there to repair or replace something.

Almost everything you install will need to be removed/replaced/inspected at some point.
 
Add to that the ELT location. While there are constraints on where it must be mounted, some thought should be given to ease of access, and visual inspection.

For those of us using a pitot mast instead of the Vans-plan bent pipe, make sure you have a service loop sufficient to unscrew the pitot from the mast and drop it straight down out of the mast far enough to reach the connections.

EFIS backup batteries have a finite lifetime - they will need to be replaced - mount them where you can get to them later.
 
Semi handi capped, built slide out shelf with panel attached , used 2 home
depot drawer slides . Can tex photo if interested! Tomcatrv4
Tex 845 464 6328
 
If you’re building an -8

From a guy who didn’t do the “gear leg tower mod”.... I would. I still haven’t done it, and I’m trying to be quite in tune with wire chafing and preventing it, but if I have to do any maintenance, I’ll do it then. Getting your hands in there with enough room to do anything seems impossible.
 
I read a lot of posts about what to "finish" before closing up this skin or that. When I see them I try to get the builder to think about what they will do when they need access there to repair or replace something.

Almost everything you install will need to be removed/replaced/inspected at some point.

+1
Build for maintenance and modifications, and establish a design goal of “never on your back with your head under the panel”. This is achievable if you take time now for some careful thought. The panels in my RV-8A, RV-8 and RV-10 come out of the plane and on the bench, as an assembly, in 15 minutes.

The RV-8A has been flying for ~18 years and is on its fifth panel. The first panel in the RV-10 lasted a total of 18 months. Assume you will similarly want to modify whatever you end up with - so plan on it. I offer that with such forethought most wire runs going to/from the panel need little to no changes when updating a panel. You are left with the easier job of buying a new panel blank, some time cutting new holes, paint and then doing the new avionic interconnections - with the panel sitting on the bench.

Carl
 
I've said this before: the second plane you build will have "ease of maintenance" as a high priority! Everything you install, you are thinking "how am I going to service this?"

This access panel is at the top of my "why doesn't Van do this?" list. Ask any 8 owner about accessing the brake masters and anything in the "cave". This has made running all the engine control cables, wiring, etc. soooo easy during construction. I wish I could say it was my idea.

And yeah, I've spent time on my back under the 6 panel cursing myself for not using anchor nuts.
 

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Wow, talk about preaching to the choir.
I just finished disassembling My Rv-6a to get it ready for the avionics shop and a new Dynon panel.
I installed SDS ignition and fuel system and hated the bolt/nut Adel clamps under the panel. Oh ya and the bolt/nut grounds that were loose.
Like you, I've had enough of laying on my back with the fuel valve under me. I actual removed it and co-pilot stick. What a joke to access some of the stuff.
My three cents of what-ever Art
 
Hinged panel for better access

When I first built, I hinged my panel at the bottom, with retaining hardware at the top. All cabling leaves from the bottom of the panel, either forward at the center, or out the sides to accomodate the tilting of the panel, which is about 60 degrees. With that, pretty much all work can be done from the top, sitting comfortably on the front seats or a hunk of foam. I've done my steam to glass major update and numerous other avionics updates and the wiring and mechanical associated therewith from the top, makes it so much easier. About the only thing I end up on the floor for is brakes.
 
I didn't build my airplane.

Unless the builder of my airplane was a 75lb dwarf with 8 fingers on each hand I am stupfied about how he managed to service anything under the panel, although to be fair it's clear when you look under it what he did and what Aerotronics did.

That RV8 access panel a couple posts up is sheer genius.

The new panel I'm in design phase of is going to be more like what Carl advocates, although I'm still not totally sure I can get there without re-wiring the entire airplane, which I really don't want to do.
 
The wiring in my plane is the worst thing about a good airplane.

Here's another tip (for RV-8's at least):

Never install the circuit breakers on the "outer wings" of the panel as in the thumbnail below.

You cannot get at the screws to change out a breaker or run a wire. They are packed in tightly and off to one side. Even getting at the inboard breaker screws is extremely difficult and it gets harder as you go outboard.

That part of the panel is riveted to the airplane so to put something else there you have to screw on a panel overlay after cutting and filing a larger hole in the panel and installing some nut-plate-nuts ;)

When I redo the panel and all the wiring behind the panel the CB's go...somewhere else. It will be a panel that somehow swings out or up so that access is within the realm of possibility.

And the main panel will hinge in some fashion as well. Don't know how yet. But I've already spent way too many hours on my side twisted under the panel.
 

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