In the bad old days of supporting analog autopilots, there weren’t software updates to dial in their performance and flying characteristics. All that has changed with Garmin’s GSA 28 line of smart digital servos that work with the GFC 500 and GFC 500X (experimental) autopilots.
Learning from the service history, Garmin has been incrementally tweaking and improving its GFC autopilot—a system that’s installed in large numbers in a wide variety of airframes—with software and hardware mods. Since some of these incremental changes were made to the GSA servos, it’s consolidating all past improvements into a single servo that has all the tweaks, creating what it calls the GSA 28 Service-Life Extension Program.