Jim:
RV-7A, Z-13/8, single GRT Horizon One and EIS-4000, Affordable Panel 3-piece XL panel.
I recently faced the same dilemma. By carefull planning I was able to get all electrical and electronic stuff mounted on the sub panel, front and back. I was even able to fit a Van's map box in the space. For those items which I mounted to the front of the sub panel (FW side) I made a stand-off bracket and modular panel (vertically oriented) attached with anchor nuts so I could remove a complete accessory panel by reaching through an opening such as my EFIS (4 screws and it's out of the way). My fuse blocks (battery bus, main bus and endurance bus) are on the cockpit side of the sub panel and are easily accessable by reaching through the EFIS opening or my EIS-4000 opening (again, only 4 screws and that's out of the way). New fuses are on the market which light up when blown. These will make for easy identification and replacement through the main panel. I was evan able to mount my AoA brain box and GRT AHARS between the main and sub panel. I chose the Affordable Panel 3-piece panel specifically for the ability to quickly and easily remove sections of the panel to facilitate access and maintenance.
I thought about swing-down panels and skin access panels but, in the end, I didn't want to worry about leaks or crawl under the panel to perform maintenance. Don't know about your characteristics but I find that age, girth and reduced flexibility (resulting from the previous 2) really make crawling under a panel difficult (in all honesty, its the crawing out after getting in that's most difficult). This method allows me to perform ALL MAINTENANCE of my cockpit electrical and electronics while SITTING in the seats. Just make sure you have adequate service loops and that they are secured when in use (velcro straps are great inventions).
It took a lot of planning and measuring (and a few drawings) but in the end, I only spent an extra 2 evenings figuring this out.
The only cockpit to FW electical I have that is not reachable from the seats is the FW grounding block.
I'm currently a DoD Acquisition Logistician and we spend significant resources attempting to improve the operational readiness of weapon systems (mostly aircraft and UAVs for me). Operational readiness is a factor of reliability, maintainability and supportability. When starting this project, I realized I coundn't impact reliability much because our parts are basically off-the-shelf commercial items. The reliability is what it is. I did buy a new roller tappet engine because that offers the hope of greater reliability. I do what I can where I can such as minimizing the number or relays and planning for proper default operation when they fail. Supportability is pretty much what it is and I can't effect that much. We have a well defined and vibrant material and repair infrastructure. My true method for impacting future supportability is to maintain the financial ability to buy parts and repairs when needed. That leaves maintainability as the only function I can impact. I expend great effort to ensure that every possible part is easily removeable for future service. In this way, I can keep my bird flying with the least amount of maintenance manhours and cost (someday, I may need to turn over maintenance to someone else if I grow to old to perform it myself). For this reason, I draw and maintain very detailed schematics and wiring diagrams - a few extra hours spent now can save substantial hours of troubleshooting in the future.
Sorry this is long but, I thought a bit of theory might shine some light on my design goals and results. Hopefully I've introduced an alternate method for your consideration.
Jekyll
