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TruTrak Gemini and GNX 375

uk_figs

Well Known Member
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Working on an instrument rating and I am having an odd issue between the TruTrak Gemin AP and the GNX 375, when I put in a "Direct To" in the 375 and activate and then switch the Gemini to GPSS mode, the AP starts a turn to the right and goes way off track. If I then reselect the "Direct To" and activate it the AP gets back on track and works fine from then on. It is as though the initial 429 data stream is either not correct or not parsed properly.
Anyone have any ideas (Andrew if you are lurking?)
Thanks
Figs
 
Figs,
I can only offer a “wild a** guess” but wonder how your A/P is getting it’s information from the GNX 375? Is the gps data going first through your ARINC then EFIS and then to the A/P or directly to the A/P (ie FMS)?

On my panel there is an EFIS/FMS switch that controls how the A/P gets its information. If EFIS is selected it goes through the ARINC to the EFIS then to the A/P. This allows selection of desired altitude, heading, navigation and approach functions through the EFIS system. If the switch is in FMS then control of the A/P via the A/P control head.

You might look at your panel and double check where that switch (assuming you have something similar) is positioned. In the past when something similar has happened to me it was because this EFIS/FMS switch was in the wrong position.
 
Figs,

Shoot me an email at andrew.barker(at)honeywell.com. I would like to get a little more information as to what is happening here. Interested in how the 375 ARINC and serial outputs are set.
 
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