Grt efis with trutrak servoes

I just upgraded my Grand Rapids efis to the Hx model with built in autopilot features. I have a trutrak autopilot installed in the aircraft. Do I really need to change to the grt servoes, or could I wire the TT ones to the Hx? It says it's "not recommended", but would they work?


Caleb

Norcalrv7 said:

I just upgraded my Grand Rapids efis to the Hx model with built in autopilot features. I have a trutrak autopilot installed in the aircraft. Do I really need to change to the grt servoes, or could I wire the TT ones to the Hx? It says it's "not recommended", but would they work?


Caleb

Click to expand...

Where is the "not recommended"?

The Trutrak works fine with the GRT equipment from all I know.

I seem to recall that GRT was actually one of the early EFIS providers to fully integrate with the TT A/P.

Of course you get a DIFFERENT level of integration when you use the GRT servos but there are other benefits to using your TT A/P along with your GRT EFIS.

James

Sorry for not being clear enough. I would want to integrate The TT servos directly to the grt efis, without the trutrak control head.


Caleb

GRT and TruTrak servo's are not interchangeable. Per the GRT autopilot installation document:

"GRT?s servos were designed as a drop-in hardware replacement for TruTrak and Dynon servos, making hardware upgrades easy for people with older autopilot systems who wish to retrofit their aircraft with a GRT system. However, our servos are digital, so the wiring configuration of other brands of autopilots will not work with GRT servos. GRT servos require fewer wires than analog servos."

The GRT EFIS commands the GRT servo's via a digital (RS-232) data bus. Each servo has an RS232 data bus output that is mulltplexed and fed back to the EFIS.

TruTrak servos are externally similar to the GRT servo's (mounting) but are controlled via stepper motor commands from the TruTrak Control head. Multiple wires are used to control the direction and speed of the TruTrak Servo. The Roll servo requires 5 individual wires plus power and ground. The Pitch servo requires 6 wires plus power and ground.

The GRT EFIS can control the TruTrak autopilot via either RS232 serial data bus or ARINC 429 serial data bus commands that are sent to the TruTrak autopilot control head which then controls the TruTrak servo's.

For some, having a separate stand alone autopilot like the TruTrak is a plus because you don't have all your eggs in one basket. On the other hand having the autopilot integrated into the EFIS simplifies the installation and operation of the autopilot.

Exactly the answer I was looking for! I was about to buy the grt servoes, but couldn't help but wonder if the 1800$ was required!

Thanks!

Caleb

Trutrak servos can only be controlled by a Trutrak autopilot.

Depending on which model of autopilot controller you have, you should get most (if not all) of the capability of the GRT autopilot. You'll need either a Digiflight II VSGV or the Vizion.

Norcalrv7 said:

Sorry for not being clear enough. I would want to integrate The TT servos directly to the grt efis, without the trutrak control head.


Caleb

Click to expand...

OK, I understand better now.

The TT control head is REQUIRED if you want to interface with the EFIS.
You cannot use ONLY the TT servos on the GRT EFIS. If you want ONLY servos, then they must be from the manufacturer, in this case GRT.

Something has to give the servos their "instructions" and the language they speak may be different. TT's control head knows how to instruct the TT servos. Their control head can take higher order instructions from an EFIS (or a navigator like a GTN 650). GRT knows how to instruct its servos. Certain higher order instructions can come from the GRT EFIS or a navigator like a GTN650 (or 430W).

James