BeechTalk - BT

Username Protected · **Posted:** 28 Sep 2025, 08:33

Username Protected wrote:

I posted this over on the kitfox forum but given the low traffic I figured I'd throw it up over here as well.

What I have on order.
Garmin G3X Touch
Garmin GTX 45R if I'm looking.
GMC 507 and 3 servos,
GTR205x Comm.
GEA 24B for engine monitor
VPX power supply
Obviously have all of the connectors, AHRS,Magnetometer, etc.

I’m building an experimental with basically the same units now.

I've been reading the various install manuals and starting to feel more comfortable with the process but still have a bunch of random questions I'd love an opinion on.
I'm putting in the Wheelen microburst Nav/Strobe lights. Should I be running a 4 wire shielded for this? There is a Ground/ Nav pwr / Strob pwr / Sync. Do I need it to be shielded

LED nav lights wiring don’t have to be shielded but I’m doing it anyway since it’s easy to run a four wire shielded wire out to the wingtip. I am still keeping them as far from the magnetometer as I can to be extra cautious. Never know what will change in the future.

On alot of the attachments I see a call to "aircraft" ground. Am I running a ground wire all the way back to a common ground bus that is then tied to the firewall or am I finding a way to ground it to the airframe closer to the actual box I'm wiring up?

For the avionics I am running a dedicated ground wire back to a common ground bus. The G3X install manual recommends this I think. Since your wings are removable, I would definitely do it for wing mounted parts. In the cowl area, it’s not much work to just run everything to a common ground point.

OAT Temp prob. I know I need this out of the sun, exhaust stream etc. Are we just putting it under the wing?

Mine is going under wing near an inspection plate. Try to find a spot you won’t whack it with your head.

Wing routing of Pitot/AOA / Wires through the rear spar at the pivot point or near there I was thinking about putting a discount on all of the wires. We will be folding the wings all the time (fits in my existing Hangar that way). Worth doing this or just adding in a point of failure.

I agree on adding a connector for the wires. I wrestled with that one too. There are high quality shielded connectors out there. I haven’t bought mine yet but will definitely add one for the magnetometer. For nav lights, I am not worried about a shielded connector. Will just pass the shield wire through a pin.

Matt

Username Protected · **Posted:** 29 Sep 2025, 09:34

Wayne, thank you for the response. Couple of follow up questions for you.

Re-grounding, for the autopilot servo's would you run a dedicated line for them or could I just ground to the metal frame?

Electrical connect/disconnect for the wings. Do you have a part number or link for the shielded connectors that you are talking about?

Finally, what aircraft are you building? How far along are you?

Cheers,
Matt

Username Protected · **Posted:** 29 Sep 2025, 23:22

I’m building a Bearhawk LSA, the smallest of the BH fleet.

I’m not doing the autopilot, so I’m not much help there, but in general, the power ground to the chassis should work if the other end at the control boxes are also grounded to the chassis. I have a ground junction box right next to the master power bus that everything ties to.

One thing I learned from Garmin about the CAN bus wire, though. For a simple system, using the regular shielded MIL C 27500 should be fine, but for more complex systems, they definitely recommended the Gigaflight wire. The data traffic for a complex system could sometimes have trouble on the 27500 wire. With an autopilot, you’re getting into the complex system zone.

I haven’t picked the shielded connector yet but give me a little time and I’ll share where I am on that one. Basically a shielded DB-9 connector pair should work, but they are kind of big. I’m looking for something smaller, like a Deutsch sealed connector.

Username Protected · **Posted:** 30 Sep 2025, 16:23

I bit the bullet and went with the Garmin recommended canbus wire. I'm probably going to introduce enough issues into the system as a first time builder that I didn't want a third party issue causing me issues when I was trouble shooting. Wire and equipment arrives on Friday, going to be an exciting weekend.

Username Protected · **Posted:** 01 Oct 2025, 14:19

Username Protected wrote:

I bit the bullet and went with the Garmin recommended canbus wire. I'm probably going to introduce enough issues into the system as a first time builder that I didn't want a third party issue causing me issues when I was trouble shooting. Wire and equipment arrives on Friday, going to be an exciting weekend.

Excellent strategy. There will probably be problems and you don’t want to give anyone an excuse to run you around with someone else. Kind of like when Gateway computers wouldn’t talk to Epson printers: “it’s not our issue, it’s theirs. Have you installed the right driver? Oh we don’t know which driver you should use, you’ll have to talk to them….”

Building a Kitfox STI, lots of ?'s