Wiring the Pitot Heater with ADAHRS in the left wing

Learned some lessons today.

1. The wiring for a pitot heater in the left wing can't fit in the grommets already running down the wing for the lights. I can get one of the wires through for the pitot heat but not two. So I can either run a 14V power line with the ground connected out on the rib, or I can use another set of drilled holes to pass a supply and ground together.

2. If I use the stock route I figure an ADAHRS in the bay will not have magnetometer problems because Vans made it that way. But if I use the upper set of grommets it might change the interference of the pitot heat current on the Dynon magnetometer.

Soooooo: how close to the dynon magnetometer is too close (affecting heading info). The pitot heat will draw 10A and then drop to 1-1.5 in contnuous use. I know there is a remote magnetometer available; but I wonder what happens to the single ADAHRS from running a 10A line in various grommet locations in the wing?

Anyone have any experience with this?

Panel mounting our AHRS

Please note for me the issue with using the wing location for our GSU 25 AHRS is that the Garmin Installation manual states "The wing is not an optimal location to mount the unit as (in addition to being away from the center of gravity) any amount of wing flex will directly translate into attitude error".
So we have instead routed our pitot and AOA tubing into the RV-14 panel, to be used for our G3X and a separate backup EFIS.

I spoke with a knowledgeable person at Dynon and was told that the MOSFET power transistor in the controller uses the case for a heat sink and thus is grounded to same; so the ground to the chassis is by design and necessary. It will also be low impedance in this configuration. In a metal airplane even if a wire is carried back to the battery most if not all of the current will pass to the mounting points of the controller box; so grounding the box to the airframe locally will make as much sense as carrying a wire back to the battery.

There won't be a way to make a balanced wire run for the pitot heat controller.

I could mount the controller in the fuselage and run the actual pitot wires balanced out to the heater. Will have to consider that; but I'm thinking now to just wire it up and if the magnetometer is affected (likely) then I'll remote it to another location, or relocate the ADAHRS/magnetometer.

I wish the RV14 kit just had a shelf for the ADAHRS in the tailcone..... It is all setup for Dynon kit and thats okay, but this is a compromise point for sure. With a Garmin setup it is moot because the Garmin ADAHRS would not be installed in the wing.

JDA_BTR said:

I wish the RV14 kit just had a shelf for the ADAHRS in the tailcone..... It is all setup for Dynon kit and thats okay, but this is a compromise point for sure. With a Garmin setup it is moot because the Garmin ADAHRS would not be installed in the wing.

Click to expand...

why not just make a bracket and mount the ahrs in the tailcone and not worry about the proximity to the heater wiring?

bob burns
N82RB

A good solution. Will make that nice ADAHRS tray in the left wing feel lonely.