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-   -   G3X autopilot coupling with ILS (https://vansairforce.net/community/showthread.php?t=182872)

AaronG 05-26-2020 02:06 PM

G3X autopilot coupling with ILS
 
I currently have the G3X system with a GTN625. I also have an independent SL30 and indicator head. The question I have is there any way to get the autopilot to fly the ILS using the GTN625, or must I hand fly the ILS? I would like to keep the SL30 independent of the G3X. Otherwise, I need to eliminate or replace the indicator head since it requires different output signal (resolver) versus G3X signal requirement (serial) from the SL30.

Aaron

gfb 05-26-2020 02:40 PM

The GTN has no connection to the SL30 or it's own ILS receiver, so cant do anything about that.

Are you able to have the SL30 output both the serial and resolver output at once? Otherwise unfortunately you get one or the other.

EDIT: Just read through the SL30 install manual and suspect this won't work, as you have to set the indicator mode to Resolver/Composite/Serial

gfb 05-26-2020 02:44 PM

Thinking this through a little further, I guess you could have the autopilot in heading mode to fly the localizer by watching the needle on your indicator and changing the heading continuously to keep it lined up. You could do the same with the VS mode for the GS. I suspect this would be really finicky though and probably a bit unsafe.

alcladrv 05-26-2020 02:52 PM

Quote:

Originally Posted by AaronG (Post 1433560)
...... I would like to keep the SL30 independent of the G3X. ........

In my -7A, my SL30 is connected to the G3X and Garmin autopilot which does a very good job of flying a coupled ILS approach.

Not sure what your rationale is, but to each his own.

AaronG 05-26-2020 02:59 PM

I was hoping the autopilot would use the GPS signal to fly the approach. The approach exists in the 625, but it appears Garmin doesn?t let it drive the autopilot (for monitoring only). I would monitor the SL30 to stay legal for the ILS. This is how it worked very well in the Chelton system I had previously.

Unfortunately, I have to pick either the indicator or the G3X due to the different SL30 format outputs.

Aaron

BobTurner 05-26-2020 03:14 PM

This is confusing. What do you want? You want the ILS to be independent of the G3X but you want to use the autopilot which is part of the G3X...
1. There are a lot of gps lpv approaches which exactly overlay ILS approaches. For those, let the autopilot fly the gps approach while officially you monitor the ILS on the SL30.
2. Change the SL30 output to serial, hook it up to the G3X. Main problem solved. What about back up if the G3X fails? Two options:
a. Shoot the localizer approach using the CDI (left-right only, no GS) built into the SL30. You always choose an alternate that gets you in with localizer minimums. Or
b. Keep your cdi, run output wires from SL30 thru a panel switch, switching between cdi and G3X. Write down on emergency check list procedure for changing output from serial to resolver. Hold somewhere, complete changeover, shoot ILS.

g3xpert 05-26-2020 03:21 PM

ILS Approach with SL 30
 
Quote:

Originally Posted by AaronG (Post 1433560)
I currently have the G3X system with a GTN625. I also have an independent SL30 and indicator head. The question I have is there any way to get the autopilot to fly the ILS using the GTN625, or must I hand fly the ILS? I would like to keep the SL30 independent of the G3X. Otherwise, I need to eliminate or replace the indicator head since it requires different output signal (resolver) versus G3X signal requirement (serial) from the SL30.

Aaron

Aaron,

For the G3X autopilot to couple to an ILS approach, you will need a NAV radio to provide the navigation information to the G3X Touch, the G3X Touch will not fly an 'artificial' ILS approach based off of GPS guidance.

You can however retain the analog connection from the SL 30 to the mechanical CDI, and wire the SL 30 via serial to the G3X, using the Garmin VHF NAV/COM setting. You will need to open configuration mode on the G3X, and select Navigation. Set Navigator 2 Selected Course to Disabled. Leave the SL 30 set to Resolver. In this case, course selection is made on the mechanical CDI, but the GDU has the navigation information from the SL 30.

Thanks,

Justin

AaronG 05-26-2020 06:10 PM

Thanks Justin. You answered my question and allowed me to keep the indicator active.

calpilot 05-26-2020 09:49 PM

I think if you select VLOC for default NAV, and have the SL-30 wired into the serial as the dedicated VOR-ILS source, the autopilot should fly it!
g.

lr172 05-26-2020 09:58 PM

Quote:

Originally Posted by AaronG (Post 1433560)
Otherwise, I need to eliminate or replace the indicator head since it requires different output signal (resolver) versus G3X signal requirement (serial) from the SL30.

Aaron

G3X displays an HSI, to replace the indicator and includes an OBS knob replacement as well. Don't understand why you would want a separate indicator. I rarely look at the HSI, as the G3X also provide Deviation Indicators on the side and bottom of the attitude indicator. I find this much easier to blend into a scan than a separate HSI or indicator, as everything need for an approach is in a 3" X 3" area. G3X also auto slews the course for the ILS. Not entirely sure this works with a 625 though. Not sure if that info is coming from the G3X or the external navigator. Dial in the frequency and press the Appr button and your done.

I can't see a reason for keeping the old indicator and giving up all of the nice G3X features.

Larry


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