If I understand correctly then in your case you lost the GP indication and therefore could not fly the RNP16. But a GFC500 would not interfere with the display of this GP, it would merely not fly the approach by itself. Which is not really a problem because you can fly it manually.
Yes that seems correct; what is not apparent is whether you get the Flight Director bars on a GFC500 installation, on an ILS, if GPS fails.
On the King APs, the FD is generated by the autopilot, not by the circuitry which decodes the LOC/GS signals which merely drives a CDI and presents you with this
Peter wrote:
Yes that seems correct; what is not apparent is whether you get the Flight Director bars on a GFC500 installation, on an ILS, if GPS fails.
I don’t (yet) have a GFC500, but my read of the manual is that there are two presentations of the FD, one filled and one “hollow”, depending upon whether the a/p is active or not. The FD bars disappear only if attitude (not navigation) information is lost. The AFMS also says that if GPS is lost on an VOR/LOC approach it reverts to ROL mode and to PIT mode if on an ILS approach. So if GPS is lost during an approach, I would expect the FD presentation to remain filled, since the a/p is still engaged even if in a different mode. If the a/p were then disconnected (manually) to fly the approach manually, the FD bars would change from filled to hollow.
It is worth remembering that we are talking here about GPS position data. GPS navigation guidance is only relevant in the case of a GPS approach.
It makes one wonder how Garmin feel they can deliver a good FD presentation of an ILS without GPS aiding, but feel unable to drive the autopilot servos with the same data 
My analogue HSI KI525A displays two yellow markers for the GP… and they didn’t show up….
Peter wrote:
It makes one wonder how Garmin feel they can deliver a good FD presentation of an ILS without GPS aiding, but feel unable to drive the autopilot servos with the same data
I wonder if it is related to cost of certification and resulting a/p price/market rather than raw capability. I believe the GFC600 and GFC700 have a different behaviour, but they are much more expensive.
The GFC500 is about $7’000 MRP + G5 & servos. Everything else I’ve seen on the market for an SEP is $10’000+, excluding the new GPS-only a/p which may be the competition Garmin is trying to address.
The Aerocruze doesn’t need GPS data, but… well…. nobody really trusts those guys to stay in the market long enough… and keeping the old servos really isn’t the best solution either, is it.
My analogue HSI KI525A displays two yellow markers for the GP… and they didn’t show up….
The KI525 GS inputs are driven directly from the NAV radio (e.g. a KX165A, or the VHF part of a GNS box). Not related to the autopilot at all.
The Aerocruze doesn’t need GPS data, but… well…. nobody really trusts those guys to stay in the market long enough… and keeping the old servos really isn’t the best solution either, is it.
I think the first part of that statement is bad enough
The King KS27x servos are mechanically very good, as is their mounting method. You can change them without disturbing the controls, and you can fly the plane with them removed. They should outlast the plane easily. The weaknesses are
Peter wrote:
It makes one wonder how Garmin feel they can deliver a good FD presentation of an ILS without GPS aiding, but feel unable to drive the autopilot servos with the same data
I don’t think they do. If the A/P reverts to ROL and PIT, so will the F/D.
Well spotted
