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Garmin G5 (merged thread)

I’m not an expert, but I was told the King flux is not nearly accurate enough to drive the current generation glass.
And I don’t think they communicate via the correct protocol neither.

Last Edited by airways at 14 Jan 14:52
EBST, Belgium

@huv, as far as I remember, installation of the Garmin magnetometer is pretty straightforward and explicitly described in the installation manual. I suspect the most time-consuming part of the installation would be finding a location least affected by other electrical circuits and magnetic objects onboard. Thus, swapping an existing magnetometer for the Garmin one should be much easier than installing it from scratch.

LKBU (near Prague), Czech Republic

but I was told the King flux is not nearly accurate enough to drive the current generation glass.

Deffo you were misinformed, because the Sandel SN3500 can use the King fluxgate (KMT112) and it is superbly accurate – within 1 degree easily

It is a passive device.

I later installed the SG102 AHRS and that uses Sandel’s own fluxgate sensor, MT102, which has a uP and communicates via RS422. The calibration data is stored inside the MT102, which is much more sensible.

It is also very accurate; again sub 1 deg after 7 years.

the magnetometer installation is the single most expensive part

It depends heavily on whether you can buy the metalwork kit, so you just need to cut a hole in the wing, rivet it in, and clean up the mess on the paintwork You could spend days just on the paint.

To fabricate the supporting metalwork could take days, though it is a bit easier if you can mount the fluxgate in the tail.

Does the G5 interface directly to a KMT112?

Administrator
Shoreham EGKA, United Kingdom

I believe my Garmin Magnetometer lives in the glass fibre wing tip. No holes required!

United Kingdom

Peter wrote:

Does the G5 interface directly to a KMT112?

No it won’t work with a KMT112. The Garmin magnetometer is a completely different beast, uses a serial instead of analogue interface and is way more sensitive to electrical noise and stray magnetic fields from lights, pitot heat etc.

Avionics geek.
Somewhere remote in Devon, UK.

and is way more sensitive to electrical noise and stray magnetic fields from lights, pitot heat etc.

Sounds like a great technological leap forward then

How on earth have they managed to achieve a greater sensitivity to a stray field of a given strength? Could it be that it is more sensitive to the vertical components of magnetic fields?

Administrator
Shoreham EGKA, United Kingdom

I can tell from my Autopilot tracks that mine is rock solid. Yet it lives somewhere next to a flashing strobe so all’s well that ends well.

United Kingdom

One should always run two (twisted pair if possible) wires to each electrical load. That way the magnetic fields cancel out. Never use the airframe as the return conductor, for anything carrying current during taxi or flight.

The inverter for the traditional strobes draws a lot of pulsating current but maybe they wired it correctly. The strobe lamps themselves should not radiate any real magnetic field.

Administrator
Shoreham EGKA, United Kingdom

The OAT probe on my dual G5 setup was installed underneath the keel of my aircraft approximately mid-way under the position where the back seats are located.

I am getting errors of up to 7 degrees C in flight due to engine heat. It really amazes me that a 180 HP non turbo engine can warm the air that much in flight. The dealer is clearly also surprised will now relocate under a wing.

Apart from on the windshield, where my mechanical OAT probe is located, I’d be interested to know where other electronic probes are positioned on other aircraft?

United Kingdom

The temperature rise of the air flowing through the cylinders is of the order of 20 degC. The data, for one particular IO540 installation, is somewhere here. Obviously it will vary with airspeed, engine power, etc.

So if your OAT probe is sitting in this airflow (which exits at the bottom of the cowling) it will read way high.

Aspen had this issue for years (and maybe still have) with their remote sensor module, which is normally roof mounted and suffers from heat from the cockpit getting conducted up through the roof. And probably other errors…

OAT probes should be mounted on the underside of the wings.

However, does the probe read correctly when the aircraft is sitting in the hangar, in equilibrium? If not, you may have a bad instrument.

Administrator
Shoreham EGKA, United Kingdom
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