According to my airframe logbook, my 2008 AMD CH601XLi-B had the original PAI-700 compass replaced in 2009 with a new one. No reason was given, but the A&P that did the replacement noted that he couldn't get the new replacement compensated satisfactorily. The 2009 replacement failed two weeks ago with 100 hours on it, and I started looking for alternatives.

MGL Avionics sells a pair of units, their AV-1 Infinity 2-1/4" LCD display and SP-6 magnetometer sensor using MEMS (Micro-Electro-Mechanical Systems) technology, which together provide magnetic heading displays similar to a wet compass, but with an accuracy of plus/minus one degree. The sensor is mounted remotely away from wiring and ferrous materials, and once the installation is completed a ten minute calibration flight is flown so the SP-6 learns the magnetic influences in the airplane and cancels them out using firmware in the box. No correction card is required, and there are no moving parts to wear out.

Attached is the bench test setup on my dining room table, and I have to say so far I'm impressed. Installation in my Zodiac (now certificated as Experimental) will take place over the next several days and I'll write up a review after I've used it a few times. 

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With the SP-6B magnetometer and AV-1 Infinity display installed, I flew the Zodiac to the Quality Sport Planes open house in Cloverdale on May 13 without flying the self-calibration flight, and noticed the compass was as much as 10 degrees off on some headings. Today the weather was perfect, so I performed the self-calibration flight over the west Marin coast near Stinson Beach, and after calibration the compass tracked the DG precisely. Although the DG had precessed about 4 degrees, the compass and DG showed the same 4 degree difference on a number of headings throughout 360 degrees.

It's amazing.

Here's downtown San Francisco showing the western span of the bay bridge enroute from Oakland to Stinson Beach.

...and here's the panel on the way to Stinson Beach via the golden gate.

Yep, Ranier is a genius! I ended up installing a different brand of efis in my 750, but I have owned MGL equipment in a couple of my other planes. I loved my Stratomaster Extreme and the other MGL products that I had. I believe MGL is the most technologically advanced EFIS equipment of all the major players. Keep us posted on its performance.

My inspection is coming up and I was wondering if the "no deviation card required" is really true in the DAR/FAA's eyes. Of course I can't do a self-calibration flight until after.signoff..... just wondering if I should make a card based on the on the ground readings or not.

I'm loving the iEFIS setip from MGL in general.

An interesting question. If the "magnetic direction indicator" can be demonstrated to have less than ±1° deviation on any heading, a deviation card would be superfluous. Since you can't fly the plane before the inspection and signoff, you can't perform the self-calibration flight. I can almost guarantee that there will be deviations of up to 10° before the self-calibration flight (at least that was true of my installation).

Catch 22.


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