from here
@slowflyer who did the install ? Did you do it yourself or an avionics installer ?
It is still in the process of being installed during my annual by an avionics shop associated with my maintenance shop.
Looks like I am running into some problems because I did not do enough research on the capability of the G5 to talk to the autopilot. Heading information works fine with the GAD29b but removing my old vacuum AI leaves the AP (Century IIb) short of attitude information which is required for basic wing levelling. Still not completely sure, how to solve that problem.
I think you’ll need to put the original vacuum AI somewhere in the panel (replace turn & bank indicator ?) from where it can drive the AP.
The G5 can’t do this.
Which vacuum AI is used with this autopilot?
For the KI256 AI there are some options but none are cheap. This is one, and the others all involve installing some “glass” stuff (Aspen, Garmin).
Also you need to check whether it is “legal” to install the old vacuum AI behind the panel. The autopilot STC might specify that it needs to be in primary pilot view. With autopilots driven by a TC (turn coordinator) it has often been the case that the TC was installed hidden behind the panel…
@wigglyamp might know.
You definitely have to keep the vacuum AI for the Century autopilot attitude source. Normally you’d take out the Turn Coordinator and relocate the vacuum AI into that position. The G5 can’t supply attitude to any autopilot other than the GFC500.
Here is the circuit diagram for interfacing G5 to old Century autopilots via GAD29B. Taken directly from the installation manual.
To me that looks like heading bug and course pointer emulation, not pitch and roll pickoff coil emulation (which is that the EA100 and GAD43 adapters, Aspen and Garmin respectively, do).
I see similar stuff for Century autopilots in the Sandel SN3500 EHSI IM. The SN3500 (I have two of them) does, broadly speaking, what the G5 does, with a lot more capability for interfacing to other things
