Peter wrote:
ne cost estimate from the US for a GFC500: about $11K plus at least one G5
That sounds about the right ballpark if you’ve no autopilot already.
I think the garmin bits can control a few different types of servo so it might just need the 507 control head, g5/ gi-275s and gad29b to interface to the ifr navigator. Without doing the servos, the panel wiring for all the other bits shouldn’t be too bad.
Hmmm I would check the servos. I doubt the GFC500 can drive any other servos.
They would be crazy to support the “traditional” servos, which range from absolutely disgraceful junk to not bad but still junk (I’ve spent many a happy day on the bench looking at the internals) and would just give Garmin (who are offering brushless servo motors) a bad name 
Peter wrote:
Hmmm I would check the servos. I doubt the GFC500 can drive any other servos.
You’re right. I checked the manual and have confused a few bits (I’ve spent much too long reading various IM’s recently). The GFC500 needs the GSA28’s which it drives via canbus.
Rumour from the US: GFC500 may be certified Q2 2021.
What sort of avionics configuration will be required? AIUI the GFC500 is actually just a control panel and the software runs in a G5, so you need to install a G5, presumably in the HSI position, or would you install a 2nd G5 in the AI position so have 2 x G5?
Is anything else mandatory e.g. a Garmin GPS?
Can any of this coexist with a Sandel EHSI i.e. replacing the KI256 with the G5?
Here’s a bit of an explanation of how it works. As a minimum you need a G5 or GI275 attitude indicator.
Drawing on top-end Garmin flight control technology from our GFC 700, GFC 500 provides crisp, precise response and optimum performance over the entire airspeed envelope of your aircrcaft. Rather than depending on failure-prone mechanical gyros, the GFC 500 system is digitally controlled, using solid-state attitude and air data sensor reference — giving you ultra-smooth roundouts, intercepts and more while also enhancing the reliability of the system. Incorporating the highly adaptable GI 2751 electronic flight instrument, or our crisp, easy-to-read 3.5” G5 electronic flight instrument¹, a mode controller and “smart” servos, the autopilot’s architecture supports full pitch-and-roll axis control capabilities with optional pitch trim for automatic and manual electric trim. Additionally, yaw damper capability is optionally available for select aircraft models.
With the optional GAD™ 29 nav data adapter (not required with GI 275), GFC 500 will interface with modern Garmin navigators such as the GTN Xi series and legacy GNS (WAAS and non-WAAS) series navigators to fly a wide range of precision, non-precision and GPS-guided approaches as well as holds, procedure turns, missed approaches and more. GFC 500 also includes built-in GPS roll steering capability, which allows smoother navigation tracking and eliminates the need for external roll steering converters. Flight director cues are displayed as command bars on the GI 275, G5 electronic flight instrument, as well as optionally on a G3X Touch G500 or G500 TXi flight display². The command bars are always in view when the autopilot is doing the flying — and may also be used for visual guidance when you’re hand-flying the aircraft. With support for a remotely installed Takeoff/Go-around (TOGA) button, the flight director can be cued to automatically indicate and capture the correct pitch attitude required to fly a missed approach and then follow the missed approach procedure loaded in your compatible GPS navigator. Up to two GI 275 or two G5 electronic flight instruments1 can be interfaced with the GFC 500 autopilot in your aircraft, providing full reversionary display capability.
One G5 is good, two G5 even better. AI275 yet better. The GFC500 will work with Avidyne IFD series too.
As a minimum you need a G5 or GI275 attitude indicator.
OK; so the KI256 would be replaced by a G5 → the primary AI+FD.
What would the G5/GFC500 be fed from for L+V? Could it even get L+V (LOC/GS) from a KX radio, and L only from a KLN94?
In a more modern setup, it would get L+V from a GPS+NAV box (GTN/IFD) since these integrate the VHF radio and have just one set of outputs. Or is it just one ARINC429 connection for both L+V for both LOC/GS and LPV?
Can the G5/GFC500 accept L+V analog signals from a SN3500 (acting as a roll steering converter)? That is a neat way to drive an autopilot because the AP can’t tell if you are flying an ILS or LPV.
Can the G5/GFC500 accept L+V analog signals from a SN3500 (acting as a roll steering converter)? That is a neat way to drive an autopilot because the AP can’t tell if you are flying an ILS or LPV.
Why would you want to do that – the G5 outputs the data via canbus to the GFC500 without needing a roll steering converter.
On top of that, the STC does not allow a CDI to be interfaced with the same navigator as the G5.
T28 wrote:
On top of that, the STC does not allow a CDI to be interfaced with the same navigator as the G5.
I found that restriction puzzling. Why on earth not?
If one has an EHSI and a G5 above it (replacing a KI256 so acting as an AI/FD, plus incidentally running the autopilot code)
then obviously having the same indications on both of these is desirable. That is what got broken on many installations when a roll steering converter was installed. I would never fly with such a system.
