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Exchange Autopilot options for a TB20

Peter wrote:

ripped out

First dibs on the Sandel if you rework your panel :-)

Peter wrote:

Can anyone guess how this would integrate into a TB20 with two Sandel SN3500 EHSIs and a GTN650+750 or 2×IFD540? AIUI, a GFC500 requires a G5, so an awful lot of good quality stuff would have to be ripped out.

You can install G5 as an AI, and replace current A/P controls with the GFC controls…

EGTR

Replacing the KI256 with a G5+battery (and removing the vacuum pump) is a good option.

However what would control the GFC500 L+V? Would it come via the G5 (from the navigator+radio box) or would it come directly from the nav+radio box? The latter method is fairly common in the GA context and means the “HSI” is doing one thing and the autopilot is doing another. This is what I currently have (KFC225 driven from the KLN94 (in GPS mode) or from the KX165A (in LOC/VOR/GS mode) but it works well since the SN3500 course pointer follows the KLN94 track change instantly.

My longer term plan is to drive the KFC225, still via analog like now, from the SN3500’s “FCS” output, which then delivers (transparently) ILS/LPV with no weird buttonology. The KFC225 can take in ARINC429 steering but it doesn’t give you anything if you are using the SN3500 as the roll steering converter which is what this would be. Both my two SN3500s have the $1000 roll steering option.

If the G5 is acting just as an attitude source for the GFC500 then the steering to the GFC500 must come direct from the nav+radio box, and presumably it needs to be one which outputs ARINC429 for both H and V for both LPV and ILS?

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

However what would control the GFC500 L+V? Would it come via the G5 (from the navigator+radio box) or would it come directly from the nav+radio box?

AFAIK GPS→G5→Servos.

EGTR

You mean GPS → GFC500 → servos?

Administrator
Shoreham EGKA, United Kingdom

I think arj1 is actually correct – the GFC500 is just a panel, the brains are the instrument – G5 or GI275.

tmo
EPKP - Kraków, Poland

Peter wrote:

You mean GPS → GFC500 → servos?

No! I meant exactly that – servos are controlled directly by G5 (or G3X in some newer models), just like tmo has said.
Try to find GFC500 webinars on Youtube – there were quite a few, with full description of the config by Garmin.

EGTR

One cost estimate from the US for a GFC500: about $11K plus at least one G5 or Gi-275 to provide attitude and airdata to the autopilot, plus installation labour. Not known for sure as there is no STC. So probably in the area of €20k+ in Europe.

Administrator
Shoreham EGKA, United Kingdom

(deleted)

Last Edited by Airborne_Again at 06 Nov 10:22
ESKC (Uppsala/Sundbro), Sweden

Thread title “Exchange Autopilot options for a TB20”

Administrator
Shoreham EGKA, United Kingdom
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