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  #1  
Old 09-12-2019, 07:41 PM
Carl Froehlich's Avatar
Carl Froehlich Carl Froehlich is online now
 
Join Date: Dec 2007
Location: Dogwood Airpark (VA42)
Posts: 3,268
Default Building for maintenance and modernization

I key design element common on the three RVs I built is ease of maintenance and ability to upgrade as opportunity presents, without too much pain. Toward that end I make sure I never violate my rule of ?never be on my back with my head under the panel?. This translates to a panel that is fully removable for work/modification on the bench.

The RV-8 has been the most challenging for this as the towers tend to be a real PITA for wire runs. Even so, a full IFR, dual EFIS screen panel is achievable inside this design requirement.

In simple terms, wiring is divided into two elements:
- Wiring between components that stay on the panel, as example for the RV-8 this is the GTN-650 and the audio panel. Breakers for these components are also on the panel, power connected via a large pin Molex connector.
- Wiring (and all other breakers) are mounted off the removable panel. On the RV-8 the panel wings provide this space. On the RV-10 it is the lower panel skirt. The SkyView displays are all connected via D connectors, so all that wiring stays in the plane when the panel is removed.
- Connecting between the panel elements and the rest of the plane is done via two 25 pin D connectors - of which only half of the pins are used. The rest are available for future options.

This first photo was taking after all the rough wire runs where done:

This photo is after all the behind the panel connectors are done:

This is the back of the panel showing the interconnections and the connections to the rest of the plane.

Here is it all assembled and first panel power up.


I advise builders to keep in mind that the perfect panel they build will be modified many times over. My 2002 RV-8A is on its fifth panel. The first panel in the RV-10 lasted only 18 months. If you stick with stock aluminum panels from Van?s a new panel is ~$26, some time cutting holes and paint.

Carl
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  #2  
Old 09-19-2019, 11:30 AM
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wjb wjb is offline
 
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Great plan! I did the same for my -7. I can completely pull the panel in less than 10 minutes. Quick disconnect the pneumatics to the steam gauges and ADAHRS, disconnect the cable bundles, remove the screws and out she comes.

Side view of connector array:


Back view of connector array:


Pulled panel on the bench:


Backside (almost complete):


No need for back aches!
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  #3  
Old 09-19-2019, 12:05 PM
Ralph Inkster Ralph Inkster is offline
 
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Location: Calgary, Alberta
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That looks great for the '5 year back ache'.
Any solutions for the 'annual back aches'? As in maintaining fuel pump filters & brake pedals in a 8?
I sure could use some.
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  #4  
Old 09-19-2019, 03:17 PM
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Carl Froehlich Carl Froehlich is online now
 
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Quote:
Originally Posted by Ralph Inkster View Post
That looks great for the '5 year back ache'.
Any solutions for the 'annual back aches'? As in maintaining fuel pump filters & brake pedals in a 8?
I sure could use some.
The fuel filter in an 8 (assuming a standard AFP unit mounted in the standard location) is not all that hard (and easy compared to RVs with tunnels) once you get the pilot seat ramp and floor out. They need to come out anyway to inspect the control linkage.

Brakes - just always bite the bullet and take out the forwarded baggage compartment floor. Simple once you do that as you go in from the top. Get a 45 degree or so degree adapter for you electric driver and you will find it easy to get the floor screws in and out.

Carl
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  #5  
Old 09-19-2019, 05:03 PM
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pjc pjc is offline
 
Join Date: Apr 2012
Location: Tampa, FL
Posts: 206
Default Excellent advice

Having just spent (far) more time than anyone should on my back for a (simple) Transponder/Comm/Intercom upgrade I think this approach makes tremendous sense. I still have a steam to 1st gen glass update to do, and would be far happier doing it on the bench.

With proper maintenance and good luck, I hope to be flying my RV6 through several future generations of the electronic bits. If I thought I could stand the initial downtime hit to fully rebuild/rewire the panel in this fashion I would do this now (and probably should).

Those of you building *know* you know exactly what you want (today). Those of us flying know that will certainly change. Plan for many happy upgrades!

Peter
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  #6  
Old 09-19-2019, 06:31 PM
BillL BillL is offline
 
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Location: Central IL
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A couple of questions.

Reliability - have you found and identifiable issues with the additional connections?

Wire Identification - I see a lot of white wires, a) how do you mark./identify the wires b) does wire marking remain after installed?

I am small and slightly flexible, but crawling under the panel has is increasingly wearing on the old torso. Is the selection and placement of all the parts for easy assembly (and such) a trainable skill with rules that are available?

Thanks for posting this!!
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  #7  
Old 09-19-2019, 07:32 PM
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Carl Froehlich Carl Froehlich is online now
 
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Quote:
Originally Posted by BillL View Post
A couple of questions.

Reliability - have you found and identifiable issues with the additional connections?

Wire Identification - I see a lot of white wires, a) how do you mark./identify the wires b) does wire marking remain after installed?

I am small and slightly flexible, but crawling under the panel has is increasingly wearing on the old torso. Is the selection and placement of all the parts for easy assembly (and such) a trainable skill with rules that are available?

Thanks for posting this!!
Bill,

If you question is for me then:
- Reliably, no problems on the multi year (and now 5th panel mod) on the 8A. No problems on the seven year (and now 3rd panel mod) on the RV-10. Note - I use a fraction of the connections that Bill Bencze has as all the non-panel related switches are not mounted on the panel - and stay in the plane when the panel comes out so perhaps he can share his experience. Disclaimer - if you use junk connectors and wire it makes little difference how you do it, you will have problems.
- Wire identification, I consider this just one step above useless. I carefully document what connects to what, via which conduit run, which switch, which connector and which pin. This has proven to be the real gold when it comes to maintenance or a panel mod.
- Placement, this is where you should spend some time. There is a logical approach and I suspect you will see it once you work it.

Carl
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  #8  
Old 09-19-2019, 11:05 PM
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wjb wjb is offline
 
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Location: Half Moon Bay, CA
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Quote:
Originally Posted by BillL View Post
A couple of questions.

Reliability - have you found and identifiable issues with the additional connections?

Wire Identification - I see a lot of white wires, a) how do you mark./identify the wires b) does wire marking remain after installed?

I am small and slightly flexible, but crawling under the panel has is increasingly wearing on the old torso. Is the selection and placement of all the parts for easy assembly (and such) a trainable skill with rules that are available?

Thanks for posting this!!
Hi Bill L,

1) Reliability: With good quality locking connectors, there is no issue with reliability (Like Carl said). These make very solid and reliable connections, esp if you have the proper crimpers and use aerospace grade pins/sockets. However, fewer connections are more reliable than more (and fewer are cheaper!)

And like Carl said .. DON'T use junk connectors! As a lifetime electrical engineer, 95% of the problems I've seen come from connectors and power supplies. You can't practically change the power supplies used in the avionics, but you can choose the connectors. Solid body, gold plated crimp pins are what you want. Garmin sells good stuff; don't know about the others. NEVER use a connector with solder terminations in an aircraft. The natural in-flight vibrations will cause the wire to break at the solder joint in short order.

2) As for marking the wiring: I marked both ends of every wire with a heat shrinked wire ID so I can easily tell what's hooking up to what. I used a Dymo Rhino printer with their heat shrink tube (use theirs, 3rd party compatible products don't work well). It takes a little extra time, but in the end it's worth it (though I did buzz every connection to be sure I got it right). The marking helps to organize the runs and match them up to the right connector quickly. This marking remains forever; very solid. I also have a full schematic of the whole design, so the wire making acts as a good cross reference to the schematic when I terminate each connector.

3) "Is the selection and placement of all the parts for easy assembly (and such) a trainable skill?" Yes; if you know what you want to do: removable panel, removable elx pallet that lives above the rudder/brake assy (this is what I did), I designed the system to make it happen, but using aviation grade assembly and termination techniques. FAA AC 43.13-1B is your best friend here. Also, talk to other builders and learn from their experience/scars.
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Last edited by wjb : 09-19-2019 at 11:26 PM.
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  #9  
Old 09-21-2019, 03:45 AM
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JoopSJ JoopSJ is offline
 
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Location: The Netherlands
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Quote:
Originally Posted by wjb View Post
Great plan! I did the same for my -7. I can completely pull the panel in less than 10 minutes. Quick disconnect the pneumatics to the steam gauges and ADAHRS, disconnect the cable bundles, remove the screws and out she comes.

...

No need for back aches!
Hello Bill. That looks very neat!
How did you carry-through the shield ground of the CAN bus. Did you connect it to the casing of the big connector or did you assign it to a pin?

Also, can you give me the part number of the connectors you used?
Thanks
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  #10  
Old 09-21-2019, 06:28 AM
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This is an important topic, and not just for the panel. When adding anything anywhere on the aircraft, a builder should ask himself, "Will I be able to get to this later on?" and "Will I be able to get a wrench on this to check the torque?"
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