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  #51  
Old 12-04-2020, 08:40 PM
N49ex N49ex is offline
 
Join Date: Apr 2015
Location: Wheaton, Illinois
Posts: 109
Default Panel Wiring

I wholeheartedly support the idea of documenting your wiring with a spreadsheet. It has many advantages: 1) It is much easier to keep up to date than a schematic; 2) It is searchable for finding things; 3) It is much more compact than a huge schematic; 4) If you are starting from avionics, it is easier to add/integrate the rest of the plane's electrical wiring in the same data base.

Regarding access and the pain of being upside down under and behind the panel, of course removable panel sections help, though not for the connectors at the back of a radio stack. But, another thing to consider, and I am amazed how we don't see this done much, install all your exiting wiring in such a way that it can allow panel movement, and hinge the whole panel at the bottom. Mine is that way, and when it's time for mods it swings back to a 50 degree angle and I sit comfortably on seats or the spar and work away over the top of the panel.

One more thing - I don't understand the comments about the heavy connectors on the Garmin display - The are tightly screwed to the back of each unit mating connector and have great integrity, and in a flying installation, the cables most likely would get supported and tied off anyway. What else did anyone expect to do to "support those heavy connector"?
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  #52  
Old 12-04-2020, 09:10 PM
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AlexPeterson AlexPeterson is offline
 
Join Date: Sep 2005
Location: Maple Grove, MN
Posts: 2,404
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My first wiring behind the panel started out reasonable, but evolved into a rat's nest after 15 years, although not as bad as the OP's picture. After 15 years, I redid the entire electrical system, at least all of it between the firewall and the panel. I vowed that I wasn't going to climb under the panel again for making modifications, etc. I built the entire avionics wiring harness while sitting in the aircraft seats. This picture shows how every single avionics harness come through a central "node". I wanted to be able to pull any connector off from something and bring it out aft of the panel, should I want to add/change something. The view is towards the 10 o'clock position, with the connectors out of the picture's lower left. This is not the final product, lest someone notes that things are not tied down enough:



Another view which shows the long bundles:



I do not seem to have a picture of the bundles in final position, but without the EFIS in place.

This scheme might have added a few pounds of wire, but it is worth it.
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  #53  
Old 12-04-2020, 09:12 PM
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1001001 1001001 is offline
 
Join Date: Dec 2014
Location: Just Minutes from KBVI!
Posts: 1,128
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Quote:
Originally Posted by PaulvS View Post
The electrical wiring 'diagram' that came with my airplane is not a traditional line drawing. It is actually an Excel spreadsheet with a full listing of every line and where it goes 'from' and 'to'. Each 'from' and 'to' connection is simply the plug/switch/connector name and pin number.

This is essentially how our controls engineers do industrial wire pull schedules. The wiring diagrams show terminations on I/O cards, terminal blocks, field junction boxes, field instrumentation and final control elements, etc. Then the wire pull schedules are created, filling large spreadsheets with the details, and in the process generating the wire labels. So each circuit is named with its origin and termination (which are references to locations on the wiring diagrams, not the actual terminal point), and sometimes codes that indicate gauge and other information. It's very comprehensive, and just by looking at the wire label you can very quickly find the appropriate drawing number. It's just a lot of work to do up front, but it helps troubleshooting and maintenance down the road tremendously.
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  #54  
Old 12-04-2020, 11:54 PM
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Pilot135pd Pilot135pd is offline
 
Join Date: Jan 2019
Location: Vaca Moo Airport - TA37 in East TEXAS
Posts: 1,388
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Quote:
Originally Posted by KatanaPilot View Post
If anyone did name the shop, they run the risk of running afoul of DR's rules - since it's possible that this shop is an advertiser on VAF. That might be considered vendor bashing.

I do agree that many of us rely on word-of-mouth for decisions on where to have work done and that knowing would be beneficial.

When one group considers you a saint, it's hard to convince people otherwise - but these pictures are pretty telling in my view. I'd be embarrassed if I had done work like that, even though I'm just a novice. I'd be beyond mad if I'd paid a "pro" shop to do this.
I was waiting to read the entire thread to make the same comment then I found yours. It's easy to call out a shop but it can get you banned on the forum so bad shops and companies keep doing the same thing over and over. I know I complained once here about one of the advertisers and got flamed. Over a year later and I keep reading they're still doing the same thing. As long as they only read the cheerleader posts they'll never change.
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Exempt by 3 out of the 10 ways but I still donated.
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  #55  
Old 12-05-2020, 05:56 AM
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Walt Walt is offline
 
Join Date: Aug 2005
Location: Dallas/Ft Worth, TX
Posts: 5,936
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Quote:
Originally Posted by PaulvS View Post
The electrical wiring 'diagram' that came with my airplane is not a traditional line drawing. It is actually an Excel spreadsheet with a full listing of every line and where it goes 'from' and 'to'. Each 'from' and 'to' connection is simply the plug/switch/connector name and pin number. While I do know how to read and follow lines on an electrical schematic, I've found this Excel database approach to be much easier and flexible and I'm convinced that this is the way to go in the digital age.
And I'm really grateful that the previous owner/builder provided such good documentation, apart from making electrical maintenance much easier, I have also learned a lot from it that I can apply to my RV project!
From my perspective a to/from list offers little/no help when troubleshooting or trying to figure out the "big picture" of the system architecture.

The organization of the 'lists' are tough as well as many things go multiple places so if you try to list it by LRU you have tons of repeated items.
I've seen them done that way and even tried it once but gave up as it was just not clear at a glance what did what.

I'll take a good system schematic any day.
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  #56  
Old 12-05-2020, 07:09 AM
bill.hutchison bill.hutchison is offline
 
Join Date: May 2020
Location: Northern VA
Posts: 154
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On the strength of this thread I ordered Ausman's book and started reading it yesterday.

I've spent the last 25 years in telecom, and while I sold my soul to the dark side (sales engineering) I was a field technician for the first 10 years or so.

What strikes me as interesting is that the major concepts of wiring the aircraft are not that dissimilar from wiring up a large phone system. I'm finding the idea of wiring my own stuff not as scary as I initially thought - although some of this is also encouragement coming from Carl, too.

I used to know how to lace cable runs in ceilings and electrical rooms and I recall enjoying it. Wonder if I still do....

Anyway. I'm looking at options for upgrading my panel - have talked with Stein, Aerotronics, AFS and a couple of locals to get my head wrapped around costs, ideas, etc. I am thinking I may opt for having a panel pre-wired to itself, but handling the rest of the installation myself. I'm not sure yet.

The idea of something like AFS's ECB or Vertical Power is very appealing in some ways.
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  #57  
Old 12-05-2020, 08:02 AM
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Carl Froehlich Carl Froehlich is offline
 
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Location: Dogwood Airpark (VA42)
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A lot of good discussion on documentation, and pros/cons on using schematics. Some thoughts:
- Block diagram component drawings are great for understanding what talks to what.
- Documenation of what wire runs go where (e.g. to left wing, to tail cone, etc.) is well worth the time.
- For those of us that have fully removeable panels, the most critical documentation is what pin does what on each connector. This includes the GTN-650 (or whatever) tray. This element is absolute gold when it comes time to upgrade or modify something.
- After helping and an RV-14A building wire his plane using the Van’s wiring kit I was frustrated on how hard the provided schmatics proved to be in practice. You want to know what pin goes to where you need patience and a piece of paper to take notes (especiially when trying to figure out the plethrua of unneeded Molex connectors that are part of the wiring kit). After that experience, combined with replacing some wire runs with shielded wire, I decided the next RV-14 (if there is one) would not use the Van’s wiring kit.

On panel strategy. I recommend your first step is to decide what stays in the plane and what comes out with the panel. The RV-10 has a nice lower apron for mounting switches and breakers for stuff that does not feed the panel (master(s), lighting, boost pump, etc.). The RV-8 also has this capability using the two panel “wings”. Combine this with all the panel interconnection wire in that comes out with the panel (radios to audio panel, a power connection for panel component breakers, etc.) and you greatly simply the connectors needed to do all this. Once the panel is out you have full access to the stuff still in the plane (e.g. remote mounted radio and XPDR, EMS, ARINC, switches, breakers, etc.).

The hard rule is “never on your back with your head under the panel”.

Below photos are how I did this in my RV-8. The RV-8A and RV-10 followed the same approach.

Carl

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  #58  
Old 12-05-2020, 08:13 AM
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DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
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Guys, a mess like the one Vic posted is a not a skills problem. An avionics rat nest is a function of care, not knowledge, so don't be intimidated. The job is mostly "connect A to B" exactly as shown in the device manual. The dozen or so new skills are easy. The rest is neatness.

Education and recreation. You can do it.
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  #59  
Old 12-05-2020, 09:05 AM
Aluminum Aluminum is offline
 
Join Date: Jul 2017
Location: San Jose, CA
Posts: 312
Default schematic software

What software are folks using to draw up their system schematics? I find Van's harness diagram for the -14 to be barely usable, on the computer screen or when printed on A size paper. That mega-PDF really requires a large format printer to be legible, and even then it would be a pain to trace the wires across a giant printout. I'm considering using a PCB design package such as Eagle, with one connector per page.

Would anyone care to post an example of the excel spreadsheet approach?
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  #60  
Old 12-05-2020, 09:33 AM
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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 Aluminum View Post
What software are folks using to draw up their system schematics?
I went with visio to do the drawings .. all B sized (11x17) pages so that I can easily print then and put them in a binder.

Even though I have lots of experience with schematic capture / PCB layout packages, I opted for a pure graphic schematics since 1) entering in all the connector details is a PITA, and 2) I wanted the drawings to look nice (schematic capture packages are not known for their attractive output)

However, if I had to do it over, I'd either go through the effort to use the CAD tools, or go thin and do the spreadsheet version.

The key benefit of these two options is that you get a nice, maintainable netlist of all the connections .. this is the only real thing you need when you go to wiring the plane. The CAD tools will also track components and connectors, etc, so you can generate a maintainable list of what to order when the design is ready to cut wire.

Like mentioned above, the wiring process is pretty easy once you master a few simple skills, but I found it to take alot longer than expected to plan the routing, label all the wires, lace, terminate, and test. Patience is key, but it is WAY easier the doing fiberglass work!

Also, a pro-tip: Buy a roll of lacing cord and learn to lace your wires instead of using cable ties. Once you learn how, you'll never go back.
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