GMU 11 Magnetometer

[olyolson]

I have a G5 with a backup battery that derives it's heading info from the gps. I'd rather have magnetic heading in the G5 so looking into installing a GMU 11 and ditching the whiskey compass.

- Will this legally satisfy the requirement for a compass?

- I'd like to mount the GMU 11 behind the baggage compartment in my RV-4 and read the Garmin magnetometer manual for the GMU 44 (can't find a manual for the GMU 11). It says I need to mount it 10' away from any electric motors. I have my Trio autopilot pitch trim servo on the floor behind the bagge area in the tunnel and I'd like to mount the GMU 11 back there but will the GMU 11 also need to be that far away from a Trio pitch servo? I have an electric elevator trim motor in the tail.

- If I go to the trouble of mounting it in a wingtip will the NAV/Strobe lights cause a problem?

[noelf]

The GMU 11 installation is covered in the all inclusive G5 Instalation Manual. The manual also contains a section for determining if the target location of the GMU 11 will be sustable to interfearance.

[Timberwolf]

Great product for the G5. I have mine mounted in the tail of my 6.I don't have a trim motor but I have no interference issues from any of the lights or ELT in that area. I haven't read anything definitive for it replacing a whiskey compass but for me, I'll continue to use it as such until I'm told otherwise.

When I flip on my nav lights it goes to 200% interference on the test for a brief second and would technically fail the test. However, it shows no anomalies during operation and has suited us just fine. Also, installation instructions for it are in the G3X manual.

[SMO]

On my Rocket, I mounted the magnetometer in the middle of the rear section of the fuse. I made a shelf that spans the upper longerons and put it on there. My elevator AP servo is at bellcrank (just aft of the baggage) in the same place I suspect yours is. I have wires for the elevator trim and rudder light running on the floor. And of course there are the steel rudder cables running through there as well.

My unit is a GMU22 but I doubt it is less sensitive than the GMU11. I passed all the tests with the unit in this location.

[RV6_flyer]

Originally Posted by olyolson

I have a G5 with a backup battery that derives it's heading info from the gps. I'd rather have magnetic heading in the G5 so looking into installing a GMU 11 and ditching the whiskey compass.

- Will this legally satisfy the requirement for a compass?

The requirement is not for a compass but for a magnetic heading indicator.

See CFR Title 14 part 91.205 (3).

A compass meets that requirement as well as a G5 with a GMU 11.


I have two G5s and a GMU 11 in my RV-6 for several months now. I also have a compass. The GMU 11 with the G5 meets the requirement of 91.205 (3) in my aircraft if I remove the compass. On Experimental aircraft, 91.205 only needs to be complied with for VFR Night and IFR operations according to the Operating Limitations issued in accordance with the latest version of FAA Order 8130.2. (and all earlier versions going back 20+ years)

I mounted the GMU 11 on the deck under my vertical stabilizer. Running the interference test called out for by Garmin, I pick up NO interference. Was planning on putting the GMU 11 half-way between the elevator bellcrank and the tail but it was much less work to install it under the Vertical Stab. IF there had been interference, I would then have moved it.