Electrical Plugs at Wing Roots

[Cherrybark]

It would be so convenient to complete and test all of the wiring here in the garage workshop. Both wings will have AeroLED landing lights and strobes and one wing will have a magnetometer. Having plugs or terminal strips to make the connections is so tempting.

Are there any significant downsides to having these plug connections?

Any favored plugs?

[Esser]

I think I know what you mean. If you do a walk around and check your lights every time you fly, will notice if you have a problem with your connectors. I'm planning on having connectors on everything in the wing so I can remove the wing if required without cutting wires. Just my take on it.

[Floog]

Carl, I have the same lighting set-up as you on my plane. However, my magnetometer is in the fuselage. I used Molex 6-pin plugs behind the seat. I ran a 6 conductor cable w/bare shield down the rear spar. The strobe drivers are in the wingtips. All of it works great with no noise whatsoever!

[jiott]

I used the weather-tite connectors (forgot the brand name) on my wing wiring. Its like a Molex, but has the rubber gaskets for each pin.

[Cherrybark]

I thought a fuselage mount would be great for the magnetometer but the Garmin G3X system came with their GMU 11, solid state magnetometer that is very sensitive to magnetic fields. The manual specifies a minimum of 10' from electric motors and relays, including servo motors. Using Kitfox factory mounts for the autopilot servos put my AP pitch servo near the elevator bell crank towards the rear of the fuselage. So a wing mounted magnetometer is in my future.

Can you tell me more about how you wired the lights? AeroLED says the braided shield can be used as the "Black" negative/ground wire without any radio noise. Seems odd to have varying current running in the shield as the landing lights are wig / wagged but I know just enough to be dangerous.

Again, showing ignorance of wiring, what is a "bare shield"? And what type of wire did you find that offered 6-conductor 20 AWG? I'm only finding 3-conductor in official TEFZEL aircraft wire. Whether or not that grade of wire is really necessary is probably worth a separate thread that would go on and on.

[jmodguy]

Cherry
I am using DB9 (computer serial port) connectors at my wing roots. These are very affordable (cheap) and easy to put in small places. You can get a bag of 10 for a few bucks at Frys or similar electronics store. Be sure to use mil spec machined contacts. We use these on mil aircraft. The rolled contacts can be iffy at times and it is harder to get consistent crimps.
I am using a 4 wire unshielded cable in my wings. This allows for wingtip wires for nav, strobe, ground, and sync.
I used a 3/8" OD polymer tube from Lowes as a conduit to route the cables to the wingtips. I cut a small hole where the OAT and magnetometer wires head to the fuse. Plenty of room for the quad cable and 4 wires from my magnetometer.
As for using the shield in a cable (term for a multi wire jacketed "wire") as ground, I would NOT recommend this. The shield is designed for noise mitigation (EMI), not current handling. Some of the tefzel cables use a silver plated braid that corrodes rather easily and you would not want that to be carrying any current.
Do you need Tefzel wire? nope. a lot of your car wiring is not tefzel, even in the engine compartment. The reason mil aircraft use teflon based jackets is the noxious fumes PVC puts off when it burns. Tefzel is pretty nasty too, it just has to get hotter.
I have been wiring military and civil aircraft since 1980. I currently work for a DoD contractor in the wiring and interconnect department and can go on for a bit about wiring best practices and techniques...

Oh - the connector on the fuse should have female contacts so you do not inadvertently short any pins (there will be power on one or more).

[efwd]

Thanks Jeff. I never understood why the instructions instruct what end of the wire the female and male connectors go on. Now While wer on the subject Ill hijack Carls thread since he will want to know as well. Without spending $150 on a crimper, where or how would one get the 6AWG battery cable connector crimped onto the cable. I bought a really nice multi head ratchet crimper but it turns out that it wont handle 6AWG
Eddie

[Floog]

The cable is:
Nova Electronics Strobe Cable Made is USA

The bare stranded wire (grounded at ONE END ONLY) is in contact with a metal shield under the insulation. I used one of the (6) conductors as aircraft ground. The other (5) are for position, landing/wig-wag, and strobe lights.

[Cherrybark]

Jeff,

Thanks for those comments. Being retired software, I've been surrounded by DB9 connectors, just never thought of them in this context. When using shielded, do you solder or connect the braid to the cases?

I saw your idea of using the 3/8" OD polymer tube in an earlier thread. Promptly returned my unopened bags of official conduit and bought a nice length of poly for a fraction of the cost. Great idea, and I like the smooth walls.

Do you know offhand if the magnetometer is doing the analog conversion at the unit and sending digital in the wires? I would think digital transmission would be less subject to noise. If digital, I would be less hesitant to use non-shielded, 4-strand for the lights and run the magnetometer wires through the same spar.

I'll be happy to move away from Tefzel and enjoy the wider variety of color choices. Would you go so far as to use Tray Cable or is tinned better?

[Cherrybark]

Floog,

I really appreciate that specific recommendation for wire. Excellent to have rather than spending hours digging through on-line catalogs.

[Floog]

If memory serves (iffy), I got 42 feet of the cable gratis from GS-Air. Hope this helps, Carl. You'll need another run for your ADHRS.

[Dave S]

Carl,

I thought about making a junction at the wing root; but ended up going simple and cheap while reserving enough of a service loop at the root to permit the addition of connectors or a junction block if I some day needed to remove a wing or two. So far, 8 years of flying and I haven't found any reason to remove a wing...but there is enough wire in the service loop to cut and install connectors.

[PapuaPilot]

I choose to use Tezfel wiring throughout my plane. Yes, you can use other types of wiring, but there are good reasons why there are standards for the wiring that goes into certified aircraft.

How often do you think you will need to remove the wings? After lots of thought and advice I decided not to put connectors at the wing root. Every connector is a potential source for problems (poor connections, corrosion, etc.) and EMF (noise) if it is a shielded wire. I have lots of experience finding corrosion in connectors, including wing root connectors. I really didn't want to put a connector in the magnetometer wiring, it is a very sensitive sensor. I made my wing wiring so it could easily be disconnected and pulled out of from the spar tubes if ever need be. It would only take a few minutes to do this after opening the wingtips. I bet it will take far less time to do this than to troubleshoot and repair a problem in the wing root connectors.

Per the Garmin criteria there isn't a good place to put the magnetometer in the entire plane. I ended up mounting mine on the outboard rib of my left wing. I used shielded wiring for the nav, strobes and landing lights and all of their grounds returned in the same wire so that there would be minimal EMF. I also used stainless steel screws for my wingtips (certified planes use brass or SS).

Don't use the spar or airframe as the ground as it could lead to EMF that could affect the magnetometer. Doing so can turn the spar or airframe into on big EMF antenna.

The G3X will self test for problems with the magnetometer; they have you turn on circuits one by one while the unit is checking for interference (it is pass or fail). Initially mine failed when the landing lights were turned on and I had to reposition the wingtip connection farther away from he magnetometer, then it was fine.

[Cherrybark]

Connectors at the wing tip...sigh. Sometimes I get fixated on a solution and don't consider all of the alternatives. The Garmin magnetometer already requires a connector and I intended to have connectors at the lights as part of the tip removal. Pulling wires through the spar with a cord is dead simple. I'll skip the root connectors but appreciate all of the inputs.

[PapuaPilot]

Dave has a good point too. Always leave some extra length for a service loop or future repairs to connectors. Sometimes you can fix connections by cutting them off and redoing the connector. This is much easier than stringing a new wire.

[Dave S]

After reading Phil's post, I think he expressed a lot of wisdom regarding what works in the long run....things I did incorporate in our plane but didn't mention in my original reply.

Personal background for me......back in the days when I was operating ancient, well worn standard aircraft - rental in nature, there were always plenty of squawks that came to light, and, most of them were electrical/avionics in nature and most of them had to do with corrosion, breaks and parts coming loose at connection/junction points.

Phil's point indicating that more connections equals more potential failure points is gold. The connector that does not exist cannot corrode. The wing root is not exactly free of potential moisture intrusion on a kitfox...particularly for those of us who don't mind flying through light rain or parking outside on a camping trip

Ditto on the Tezfel wire - the integrity of this stuff and the standard to which it is manufactured minimizes problems down the road...the plating on the wire under the insulation better protects it from stuff leaking/seeping under the insulation and causing corrosion under the insulation where it can't be seen as well as providing excellent joints where required. As an aside, where multiple wires are needed for a run, Tezfel can be purchased which has color tracers on each wire to keep things organized. Selections include single or multiple bundled traced wires in shielded or unshielded configuration. Very useful when going through a wing. Stein Air shows many versions of this marked/traced wire.

Shielding - Phil's comment that using shielded for strobes, nav and landing, including a separate ground from the spar or airframe controls a lot of later frustration and confusing happenings.

One point which we probably know to be true, probably take into account; but, don't talk about much is the fragility of many of the latest, greatest, better than sliced bread electronic gizmos that we love - IMO - this stuff needs all the help it can get to mitigate problems down the line. The slightest change in electrical resistance can muck up our favorite gizmo. Using quality wiring (Tezfel, high quality connectors where required), correct procedures and securing the whole business enhances the potential for us to have many pleasant flights without being visited upon by evil electrical gremlins.

Sorry if I carried on too long; but, I think Phil's comments and guidance are gold and I wanted to support those thoughts.

[PapuaPilot]

Thanks Dave,

I learned a lot of this in my 35 years working as an A&P and from my avionics co-workers. We are doing lots of upgrades (where I work) from steam gages to digital panels. Most of the places we fly our aircraft are by the oceans and in the jungles all over the world . . . the worst case scenario for avionics and wiring.

That is so true that modern avionics use lots of little wires carrying signals that have zero tolerance for corrosion and bad connections. Build it well now and you will not have to deal with many problems down the road. Troubleshooting electrical problems, especially avionics is one of the most challenging & frustrating things you will ever do.

[jiott]

Regarding wiring installation and grounding for Aeroled wingtip lights, I followed EXACTLY the Aeroled wiring instructions and grounding. I was encouraged to do this by John McB back in 2013 (that's what they did on the SLSA's) and everything has worked perfectly.

[efwd]

Thanks Jim, for the encouraging words about following AeroLed instructions. Thats what I had planned on doing since I dont understand most of this electircal crud but I can follow instructions.
Eddie

[coachtylerm]

Thanks Jim, for the encouraging words about following AeroLed instructions. Thats what I had planned on doing since I dont understand most of this electircal crud but I can follow instructions.
Eddie

possibly dumb question here but I’m just getting to the landing and recognition lights on our series 7 and I noticed that some people have run four different wires through the wings. I have run two wires through that each have four wires inside of them. I know I’m not explaining this very well, but they go to the wigwag recognition lights and micro sun landing lights. Is that correct?

[VictorV]

possibly dumb question here but I’m just getting to the landing and recognition lights on our series 7 and I noticed that some people have run four different wires through the wings. I have run two wires through that each have four wires inside of them. I know I’m not explaining this very well, but they go to the wigwag recognition lights and micro sun landing lights. Is that correct?

I don't think it matters whether you have 2x 2-wire cables or 1x 4-wire cable. You just have to make sure they have the correct
current-carrying capacity and are shielded if they run anywhere near the magnetometer. The "other" wires you saw where possibly
used for the pitot heat, navigation lights, or magnetometer.

[coachtylerm]

I don't think it matters whether you have 2x 2-wire cables or 1x 4-wire cable. You just have to make sure they have the correct
current-carrying capacity and are shielded if they run anywhere near the magnetometer. The "other" wires you saw where possibly
used for the pitot heat, navigation lights, or magnetometer.


thank you for that Victor! I really appreciate it. I obviously knew building an airplane would be quite the task, but dang do I have a lot to learn! Ha ha