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Pitot heat and servo interference?

I?m about to mount the pitot tube one bay outboard of the garmin roll servo in the right wing. Was curious if anyone thought there would be any emi concerns when the pitot heat is on. The can bus on the servo is shielded but I will be within 12 inches of the probe. I?m thinking it should be ok. Any thoughts?
 
Hi Todd, sorry can't offer any thoughts since I installed my heated pitot on the left wing per Van's instructions.
 
Doubt it

Todd, I did the same thing and mounted the pitot on the right side. I also separated the heat wires (also shielded) from all others. I don?t think it will be an issue at all and hope to be flying in a few months so I?ll let ya know.
 
I doubt any RF produced by the pitot heat would have any effect on the servos. The signal levels matter when you are using very low energy signals (RF) but not so much when you're talking about normal voltages used to drive motors and such. Just my opinion, however. YMMV and recommend seeking input for actual experts....
 
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The magnetometer is far more sensitive than the autopilot servo. The Garmin instructions recommend using shielded wire for the pitot heat (high current draw) with respect to the magnetometer. You can find this wire at edmo.com. Some folks twist the pitot heat wires to reduce the chance of noise without the shield. My bet is you won't have any problems if you just run straight, regular wire especially if you have the pitot tube that does not have the controller. But, I try to follow the Garmin instructions to the letter....the only thing in their instructions that bother me is how they ground shields at multiple locations and at both ends sometimes.

Ellis
A&P/IA
Fayetteville, NC
RV-7a Builder, Grumman Tiger Owner
Dues Paid
 
I have seen a number of RV-14 installations with magnetometer interference caused by either the strobe lights or the pitot heat. Typically, to solve this, I would recommend running your ground wires all the way back to your avionics ground point rather than grounding locally in the wing per Van's plans. This is an easy modification now, but will definitely be more difficult when the wing is closed up!
 
Emailed Christer there at steinair and he agreed it shouldn’t be a problem. I have my wiring for the flyleds running past the magnetometer as well but everything is twisted and shielded so hoping their won’t be any interference. Obviously you can’t avoid it completely. All my grounds for everything is getting run back to the tabs on the firewall.
 
This has been discussed in great detail in a lot of threads on here. The magnetometer, nav/strobe lights, and a pitot heater all coexist without any problem for me in the left wing - except when I tried to use a heater controller; I got rid of the heater controller and the heat is on or off by the switch just like my Arrow was; no problems with the magnetometer in any configuration.

My strobe/nav wiring is not shielded.
My magnetometer is in the usual wing shelf location (GMU-22)
My pitot heat wiring is 14Ga, twisted not shielded
My pitot heat ground is on the fuse at the wing root
I used the standard Van's wing harness

Comments:
Pitot wire shielding does nothing for the magnetometer - twisting the wires does reduce magnetic coupling
Strobe/nav shielding doesn't make a diff at the magnetometer but does help Com interference; in my plane it isn't a factor

Your application:
The pitot heat in the right wing shouldn't matter to the servo wiring or CAN bus. I'd skip the controller. It generates continuous on/off transients.
Don't try to ground at the firewall; ground it at the fuse at the wing root - easier and no benefit seen with a long ground run
Do twist the wires to the pitot heat, about 6-8 twists per foot is enough in the run out the wing. Not sure it is necessary if no magnetometer nearby.
 
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