As the proud owner of an STEC55X, I depend upon a mechanical turn coordinator to drive the autopilot. In 2018 (well almost…).
Since I cannot get rid of the 55X altogether, I have tried to find a solid-state alternative to the Turn Coordinator.
Any ideas?
Let’s leave certification on the side for a sec…
What P/N is the current turn coordinator which drives the 55X?
You might be better off waiting until next year. Rumour has it there will be an upgrade package for the 55X to the new S-TEC3100. How this affects the turn coordinator issue you ask about is not yet clear.
@Peter: STEC P/N 6405-28L
@STOLman: thanks, I am already watching this.
There is a poll on Genesys’ website whereby you can say that you are willing to make a deposit towards the STC for your plane. Not holding my breath though, they may be slightly underwhelmed by the sheer number of Extra 400/500 out there…. Maybe around 2050 (that’s the year, not the number of planes).
From my experience so far: if the plane already has a G500 with the GAD43e autopilot interface option, you get good GPSS and much improved smoothness especially in the vertical plane. Replacing the troublesome TC would eliminate one source of overshooting and the embarrassing oscillations which are hard to explain to ATC while regaining control on the ILS:..
I haven’t been able to find details of the 6405-28L but it looks like a combined TC / “roll computer” i.e. it is not just a TC with pickoff coils in it or something similar.
I’ve found a couple for sale used. PN seems a bit off though: 6405-8-28L.
Maybe the best is to buy one and reverse engineer the signal.
Do you have experience working with MEMS chips Peter?
It seems to be more than just a “signal”. This box does quite a lot of other stuff. It isn’t just a TC with some encoder on the turn rate.
It is just a standard turn co-ordinator with a rate sensor. It also has a gyro rotor speed sensor that controls the autopilot ‘Ready’ light or annunciator. A very similar unit is used on the old Cessna/ARC 300 autopilots and also then Bendix King KAP140.
Are these the connections to the TC?
If so, it looks like the interface is just an analog voltage.
That’s it. Same unit used on System 40/50/55/55x/65.
