In the latest HDX installation manual the D10a has been changed to Standby Flight Display. (Although the D10a is still shown in the manual in various locations.) Is the GI 275 (ADAHRS w/AP, -20) an acceptable standby flight display?
That’s a shame. I want to use a GI 275 to drive my Century Autopilot. It seems like it would make a fine standby flight display. Installing a D10A would take up valuable panel space in my case.
Before you blame Dynon, you better take a closer look on Garmin's way more questionable stategy e.g. you may not use an Avidyne GPS to feed the GFC500 etc. Or ask Garmin about their opinion to combine their G3X with a Dynon/ Sandel/AV standby instrument.
I'm not sure the FAA would even accept this if tried to subsitute via field approval. I think due to the nature of the approval basis of the Dynon, no substitutions are allowed. That said, I THINK (educated guess here) that Dynon is working on a new generation of "Standby" intrument to replace the D10A since it is EOL in their experimental lineup. It's probably the weakest link in the system at the moment.