GRT Avionics

Technical Advisory- Autopilot & Magnetometer Improvements

Summary:

Two customers reported “small roll oscillations” or “loose autopilot performance” recently. An investigation revealed that changes to the AHRS calculations that affected yaw axis appear to be responsible. This may be more likely when certain (normal) magnetometer errors were present. The problem was eventually duplicated in the company test airplane (an RV-6A), which will be used to validate the fix.

A software fix is being pursued that will be made available by February 28, 2017. This fix will be identified on the website. Operation of the autopilot when exhibiting this roll oscillation is not dangerous, but could result in degraded ride quality.

Copied from GRT website, I'm unable to find the download for this improvement. Am I not looking in the right place or is this not available yet, if not when will it be?

We have not made a general release for this yet, but we have been testing the fix and the results are good. I'm waiting to hear from a couple customers who are also testing it. It should be on the web site within the next 2 weeks. I have test software for the Mini and HXr and will be making other versions if you want to try it. This only applies to the Adaptive AHRS and the Mini AHRS.

Why does your website still say "will be made available by February 28th 2017.

Is this advertised February 28, 2017 fix available yet?

We decided to add one more thing to the software before making a release, so I'm expecting an update for all display unit models within the next 2 weeks.