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RV-14 and 14A wiring tips

Carl Froehlich

Well Known Member
All,

The good news is this Saturday a new RV-14A received its Certificate of Airworthiness. The proud builder is Claudio Tonnini located at Old Bridge NJ (3N6). This is Claudio's fourth RV. I helped with some of the wiring. He is looking to do the first flight next weekend.

The wiring that comes with the kits and the vendor provided panel were the most frustrating aspect of getting this plane ready to fly. While I understand the team at Van's responding to customer demand to make more "soup to nuts" kits, I did not find this approach to be of value.

Here are a few of the tips I offer to RV-14 builders:
- Defer wiring until after the air frame is complete (just like you would do with any other kit). The one exception to this is to install the pitot heat controller if you are planning on using one. Take all the wiring that comes with the various kits for use as raw material when you get ready to wire.
- Immediately cut off the tiny, fragile elevator and aileron trim servo connectors and throw them as far as you can. Similarly do not use the kit provided servo wiring or end connectors. After you run a standard servo wire (a 22 gauge four conductor shielded wire works well and has good mechanical properties) install a standard Molex plug at the servo. Pot the ends of the plug in RTV to mitigate wire flex fatigue. Try to not add all the other connectors that Van's has between the panel and the servos.
- Replace the kit provided wing NAV/Strobe wire with three or four conductor 20 gauge shielded wire. Same for the tail NAV/Strobe.
- Unless you are running a legacy vacuum powered six pack, the single firewall mounted PC-680 does not have ample reserve power if you plan on flying IFR. You will need to mitigate this limitation.
- If you do build for IFR, please consider one of the many power distribution plans that provide some redundancy over the standard one battery, one alternator, one master and one avionics switch setup.
- One nice trick the boys at Van's did was to make the slick ADAHRS module holder in the wing. The downside is they made it for only one ADAHRS module and most people will want two. For you SkyView users the good folks at Dynon have an equally slick plate that lets you stack two modules on top of each other. This works well for the RV-14 ADAHRS module bracket. The multiple 1/4" tubing runs (Pitot, Static and AOA) can get a little tight.
- For the AOA users do not install the mechanical stall warning. Put a dab of mico then piece of fiberglass inside the wing leading edge to fill up the holes Van's punched for this stall warning.

For the few of you that want to make your own panel, send me a note for ideas. The top of the line panel in this plane was provided by an avionics shop. In addition to costing a boatload more than just the cost of the avionics, it ended up creating days of rework.

Not sent to disparage Van's or anyone else. Just sharing my experience. As I'm on my third RV build I'm an obvious fan of the Van's team.

Carl
RV-8A (sold)
RV-10 (sold, and I'm still trying to get over the pain)
RV-8 (empennage about done, waiting for the rest of the slow build kits)
 
RV-14 Wiring

I agree with everything Carl says, I've been struggling for months with my harnesses and quick panel. Most of my install problems (but not all)have been
related to harnesses,connectors and improper pin assignments.
Wait as long as you can, maybe they'll get it figured out by time you're ready!
Paul 140015
 
I think for any person who "gets" wiring, you can probably just leave out most of the wiring harnesses for the entire fuselage. You can almost certainly end up with a better harness by doing it yourself. I ended up using as much as I could of Van's harness wiring, but I removed all of the connectors supplied with the kit. I either used my own connectors or in many cases either used waterproof butt splices or solder connections to connect to the wiring. I'm not big on having any extra splices or connectors in the wiring though, so many many wires simply never got used. In the end I'd have saved money by just not ordering the wiring harnesses and doing it all myself. I did all the FWF wiring without kit wires too. Where I did use their wiring, I found it actually cost me time in the end, rather than saved me time.

The same I could say about the panel (more specifically the subpanel) cutting.
It was time-costly to move the radio stack from the centerline to offset to the right. Had they simply provided a blank subpanel and allowed us to cut our own radio stack hole, it would have been much simpler. If they offered a non-cut version, that would be a big bonus for builders who do their own panel layout.

It was also a waste having holes prepunched in 2 locations for headset jacks, especially being dual jacks, because that meant I had to find plastic plugs to plug one of the holes since many people will use Panel-powered LEMO jacks. And the same for the Accessory jack and music jack between the seats. Having prepunched holes in the cover forced me to A) install an accessory jack there that I didn't want/need, and B) get another plug for the hole for the music input that I didn't want there.

So this post is less "just to complain" but more to warn you that if you intend to lay out your own panel, you may want to mitigate some of these things as best you can while you build. It may be possible for you to "fix" the subpanel before you install it, saving yourself time as you start the panel work. And for the wiring, just leave it all out. You can go to SteinAir or other wire and connector sources and get bulk wire at a good cost and do it all yourself. The one place I depart from Carl's post is that I didn't even add molex connectors to things like the trim servos. I just did solder joints with 2 layers of heatshrink. It's unlikely that you'll be pulling the servo out anytime soon, and if you do, just cut it out and re-solder it. No need for a connector there at all that will corrode.

It's unlikely that a large percentage of builders will have a "standard" panel that will fit any connector provided up on the panel end anyway.
 
I ended up scrapping most of my wiring also. I wish I knew then (before starting) what I knew now, it would have made my job easier. As Tim mentioned , perhaps for someone with no wiring experience the supplied wire harnesses would yield a better electrical system. I'm sure Van's could supply a better harness is they only had one finish product in mind, but we all have different systems to connect and that is where the difficulties lie.
 
I have to respectfully disagree with most of the comments about the value of the supplied harnesses, especially for future builders.

In my case, I bought a G3X system from Stein and had them make the avionics harness and the standard RV-14 fuselage harness (for which they had just received the production drawing).

It would have been much easier to install the fuselage harness earlier in the build if it had been available but that is just a problem for early builders. I have no complaints about the large molex connectors used. I used them in my first plane I built and did all the custom wiring for. They have all worked fine for many years.

I do have a problem with the small molex connectors when you have to insert the wires in the field. You are supposed to use an insertion tool for those to get them to seat correctly. I did just cut them off and replace them. So what, the wire runs are there and the new connectors I used worked perfectly at little expense.

I have not had to run any extra wires yet. All the wires in the harness have connected up to the items they are supposed to connect with. That includes the autopilot servos. No pitot heat wire was supplied in the wing kit harness, but it is in the fuselage harness. I assume it will be in future releases of the wing kit harness. I will have to just make a short run to the wing connector.

One other caveat is for the Garmin magnetometer which goes where the Dynon AHRS is located. Stein did send me a replacement harness for that. I believe that is something that may be available as an option for future kit builders when Vans releases the magnetometer mount.

So if you are building with a G3X or Dynon system with autopilot, standard lights and standard trim units the supplied wiring will work fine, and since Stein makes them, they have a very good pedigree.

As for the extra holes that are punched for some of the items, I agree they would be trivial to do ourselves making for better aesthetics, but in my case they work just fine. If I switch to LEMO jacks in the future that will be a very small hassle.

My complaints about the panel have nothing to do with the wiring. I do find that the construction of the sub-panel leaves very little room for a full radio stack because of the small space and that forces one to really have to scramble for space to fit everything in. But, that is pretty typical of any airplane and the canopy is so nice with the hidden support struts that all is forgiven for the design.

Stein did terminate the fuselage harness forward wire ends for me so I don't know how the fuselage harness is supplied in a standard configuration. I assume you will have to terminate those ends and use the connectors of your choice to interconnect to your avionics, but again that task is not a big one.

Wire gauge size throughout the harnesses is appropriate. The harnesses are neatly done and labeled. One may prefer other connectors but the supplied connectors are more than acceptable for most builders. When your done, you have a complete and accurate wire drawing for the airplane up to your avionics suite. Not bad and not too costly in time and money.

My 2 cents
 
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