Wing Wiring - GRT Magnetometer and Autopilot Servo

[gmcjetpilot]

GRT has good instructions and recommends Magnetometer mounted in wing tip, no further aft of spar than one lightning hole (steel aileron counterweight). OK.

Q) Wing Wiring, running NAV, Strobe, Recognition/Landing Light wires with Magnetometer wires from wingtip to fuselage?
Whelen LED Nav/Strobe Microburst Cometflash, FlyLED Single Spotlight. I want to run all wires coming from wingtip (lights and magnetometer) in one conduit behind rear spar.

Q) GRT provides unshielded three twisted wire with Magnetometer. I am thinking of upgrading to shielded bundle for the Magnetometer (or Lights or both). Comments?

Q) Any preference in Left or Right Wing for Magnetometer? Preference Left or Right wing for Autopilot Servo?

 

[DGlaeser]

I have all my light, strobes, and magnetometer wires running together (since 2008) with no issues.
I don’t think shielding is needed, but it never hurts.
Left vs right is purely personal preference. No technical reason I know of to favor either.

 

[Foghorn]

I have all GRT. Magnetometer is in right wing tip just forward of the spar. I used double sided tape and mounted it to the lower skin. Good luck removing it after putting it in. I used a small 90* ruler to get it straight. All the wires run together back to the panel. Mag meter, Fly LEDS and autopilot. No issues since first flight Aug 2022 now with 217 hrs.

 

[bullojm1]

If this is the newer digital GRT magnetometer, it uses RS232 serial signaling which shouldn't be affected by the strobe power. The older legacy magnetometers I imagine are more susceptible to interference due to raw signalling being sent between the magnetometer and AHRS/EFIS.

 

[gmcjetpilot]

If this is the newer digital GRT magnetometer, it uses RS232 serial signaling which shouldn't be affected by the strobe power. The older legacy magnetometers I imagine are more susceptible to interference due to raw signalling being sent between the magnetometer and AHRS/EFIS.

Yes Sir.... Digital. I called Jon at GRT and he confirmed, as well as the nice comments above should be A-OK. I can sleep well tonight. Ha ha. Thank you.
The aileron steel balance weight (water pipe) is the biggest issue it seems, but a non issue if you don't mount it too far aft of the main spar.

 

[sf3543]

Here’s how I install them. I have installed several this way with no issues. Easy access for future maintenance by taking off the wing tip. I just run the wires for lights and strobes along with the magnetometerwires in the same conduit.
good luck.

 

[Tankerpilot75]

I have all GRT. Magnetometer is in right wing tip just forward of the spar. I used double sided tape and mounted it to the lower skin. Good luck removing it after putting it in. I used a small 90* ruler to get it straight. All the wires run together back to the panel. Mag meter, Fly LEDS and autopilot. No issues since first flight Aug 2022 now with 217 hrs. View attachment 61778

I mounted my backup Dynon D10A magnetometer the same way eight years ago when I moved it from under the elevator tray. Last summer I installed the FlyLed Works system in my wingtips and noticed the adhesive strip was curling. Removed assembly and reinstalled using a tray mounted to the wing tip as others suggested. Face it, adhesive does break down over time.

 

[walkman]

GRT has good instructions and recommends Magnetometer mounted in wing tip, no further aft of spar than one lightning hole (steel aileron counterweight). OK.

Q) Wing Wiring, running NAV, Strobe, Recognition/Landing Light wires with Magnetometer wires from wingtip to fuselage?
Whelen LED Nav/Strobe Microburst Cometflash, FlyLED Single Spotlight. I want to run all wires coming from wingtip (lights and magnetometer) in one conduit behind rear spar.

Q) GRT provides unshielded three twisted wire with Magnetometer. I am thinking of upgrading to shielded bundle for the Magnetometer (or Lights or both). Comments?

Q) Any preference in Left or Right Wing for Magnetometer? Preference Left or Right wing for Autopilot Servo?

Mines mounted in my tail under the vertical stab. Works great.

 

[gmcjetpilot]

Mines mounted in my tail under the vertical stab. Works great.

GRT says "it may be tempting to...." mount the magnetometer in the fuselage. They state the steel rudder cables and seat (shoulder) belt attachments, as well as items in cargo compartment can effect calibration. They are not wrong, but they are thinking about what some do in Van's RV's, mount the magnetometer behind the baggage compartment bulkhead. Also slider canopy affects calibration from when closed and when open. This location I think is poor. However in tail (under empennage fairing) all that is negated, as you show with good results.

In the tail I doubt the rudder cables or elevator brackets have a huge effect. I do have a rudder position/strobe as well, again minor. In tail my only thought is keep it dry, Empennage fairing needs to be weather proof, no water leaks, as in flying in rain or sitting on ramp in a rain storm. No big deal.

Tail or wing tip (lights, aileron counterweight) there is no perfect magnetically pure environment. Wet compasses have correction magnetics and deviation cards for a reason.a That is why we calibrate our EFIS electronic compasses, there are always errors. We just want them to be small and stable so we can compensate for it. The whole plane is an electromagnetic compromise.

Not only is there electromagnetic and ferrous metal interference of the compass, ALUMINUM blocks magnetism. You really need the magnetometer to be "under glass". That is why behind the baggage compartment, inside the fuselage surrounded by metal, is less than an ideal opinion. You are trying to measure earths magnetic field. Why put it in an aluminum "Faraday cage ". However even in a metal box, a magnetic compass will still sense earths magnetic field, because earths magnetic field is a stable and slow varying magnetic field, but it will affect accuracy, So less magnetic interference (be it steel or electromagnetic) and blocking of earths field is best. Wingtip and tail the magnetic sensor has fiberglass around it, so the only two choices in a metal RV.

Both will work, now I need to make a decision, drill holes, run wires. Thank you for all the replies. Learning is fun.

 

[planenutz]

Just to offer a different solution/option - I mounted mine on the horizontal deck in the tail, forward of the Hori.Stab forward spar. It's nice and easy to get to as it doesn't involve removing all the wingtip screws. Wiring was easier too, with all the magnetometer wiring on the right side of the fuselage and COM antenna coax running down the centre, miles away and unable to give any interferrence.

 

[jclark]

GRT says "it may be tempting to...." mount the magnetometer in the fuselage. They state the steel rudder cables and seat (shoulder) belt attachments, as well as items in cargo compartment can effect calibration. They are not wrong, but they are thinking about what some do in Van's RV's, mount the magnetometer behind the baggage compartment bulkhead. Also slider canopy affects calibration from when closed and when open. This location I think is poor. However in tail (under empennage fairing) all that is negated, as you show with good results.

In the tail I doubt the rudder cables or elevator brackets have a huge effect. I do have a rudder position/strobe as well, again minor. In tail my only thought is keep it dry, Empennage fairing needs to be weather proof, no water leaks, as in flying in rain or sitting on ramp in a rain storm. No big deal.

Tail or wing tip (lights, aileron counterweight) there is no perfect magnetically pure environment. Wet compasses have correction magnetics and deviation cards for a reason.a That is why we calibrate our EFIS electronic compasses, there are always errors. We just want them to be small and stable so we can compensate for it. The whole plane is an electromagnetic compromise.

Not only is there electromagnetic and ferrous metal interference of the compass, ALUMINUM blocks magnetism. You really need the magnetometer to be "under glass". That is why behind the baggage compartment, inside the fuselage surrounded by metal, is less than an ideal opinion. You are trying to measure earths magnetic field. Why put it in an aluminum "Faraday cage ". However even in a metal box, a magnetic compass will still sense earths magnetic field, because earths magnetic field is a stable and slow varying magnetic field, but it will affect accuracy, So less magnetic interference (be it steel or electromagnetic) and blocking of earths field is best. Wingtip and tail the magnetic sensor has fiberglass around it, so the only two choices in a metal RV.

Both will work, now I need to make a decision, drill holes, run wires. Thank you for all the replies. Learning is fun.

Over the past nearly 20 years, I have had 5-6 (analog and digital) mounted in the tail of different RVs with no issues that I know of.
YMMV.