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Upgrade G3X

Flyyak

Well Known Member
Friend
I am about to upgrade from GDU370 and 375 to one GDU460 10.6" touch. I have a GSU73 and a GSU25. I have a 305 auto pilot controller that works great with non touch using the Knobs for heading and altitude changes. I have all of the AOA equipment configured but learned after the fact that the GSU73 is always primary and it does not support AOA. I also have a G5 wired by RS232 direct to an SL30 (not connected through CAN buss)

I have been told that I will be able to configure AOA on the GDU460 Touch by selecting the GSU25 in config mode. Is this correct? Also that I can plug and play PFD to GDU460 and use MFD plug and select two CAN buss wires to connect to G5 so that the G5 will be backup in the event of failure of GDU460.

Is there an advantage to upgrading the 305 and if so is the 507 better or with more functions than the 307? If so is it difficult to wire the 507 which is thru the CAN buss rather than a 307 plug and play with 305 plug.

How difficult to wire the SL30 so that it communicates thru the G3X so that it will be displayed for Nav and Com functions on the GDU460 display?
 
I am about to upgrade from GDU370 and 375 to one GDU460 10.6" touch. I have a GSU73 and a GSU25. I have a 305 auto pilot controller that works great with non touch using the Knobs for heading and altitude changes. I have all of the AOA equipment configured but learned after the fact that the GSU73 is always primary and it does not support AOA. I also have a G5 wired by RS232 direct to an SL30 (not connected through CAN buss)

I have been told that I will be able to configure AOA on the GDU460 Touch by selecting the GSU25 in config mode. Is this correct?

Yes, no problem using the AOA feature that is provided just by the GSU 25 connected to the GAP 26 when you have a dual ADAHRS installation with a GSU 73 (#1) and a GSU 25 (#2). I have the same installation in my plane and have AOA.

Flyyak said:
Also that I can plug and play PFD to GDU460 and use MFD plug and select two CAN buss wires to connect to G5 so that the G5 will be backup in the event of failure of GDU460.

Yes, you can remove the connector from the GDU 370 PFD and plug it into the GDU 460 and it will start working. The GDU 460 has additional RS-232 ports, so you should be able to move any RS-232 presently on the GDU 375 MFD to the GDU 460 PFD. The CAN bus connections on the GDU 375 MFD connector can be re-purposed to put the G5 on the CAN bus. See the guidance on page 35-1 of the Rev. AN G3X Touch installation manual for upgrading a GDU 37X system to a GDU 4XX system.

Flyyak said:
Is there an advantage to upgrading the 305 and if so is the 507 better or with more functions than the 307? If so is it difficult to wire the 507 which is thru the CAN buss rather than a 307 plug and play with 305 plug.

I started with the GMC 305, upgraded to the GMC 307 when it became available to gain the nice dedicated HDG/ALT knobs, then upgraded to the GMC 507 to gain a TRK mode button when it became available. I use the autopilot A LOT, and love having everything needed to operate the autopilot all in one place. Having said that, you can easily use the knobs on the GDU 460 to select HDG/TRK/ALT in combination with your existing GMC 305 if you want to keep that.

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Flyyak said:
How difficult to wire the SL30 so that it communicates thru the G3X so that it will be displayed for Nav and Com functions on the GDU460 display?

A single RS-232 interface from the SL 30 to the GDU 460 is all you need. See page 27-25 of the Rev. AN G3X Touch installation manual.

Steve
 
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Thanks for info. Do you find that one 10.6 provides as much or more screen info as two 7” non touch. I will plan to upgrade to a 507.
 
307 vs. 507

Is there an advantage to upgrading the 305 and if so is the 507 better or with more functions than the 307?

I think that the 507 supports audio alerts for the autopilot (including a warning that the autopilot has disconnected), while the 307 does not. My Garmin autopilot has taken an unexpected nap on me on several occasions that I can recall, and a warning tone would have been nice. With my setup, all I get is a little flashing yellow “a” on the G5 screen. (I suspect an audible warning of an autopilot failure is actually *required* for a certified autopilot, but I may be wrong.)

The 307 is still for sale out there — for example, see:

https://www.aircraftspruce.com/catalog/avpages/garming3x11-13822.php

but given that the 507 costs the same, I can’t figure out why anyone would buy a 307. I may well be missing something.

I asked, and Garmin offers no upgrade path from the 307 to the 507 other than “buy a 507.”
 
Thanks for info. Do you find that one 10.6 provides as much or more screen info as two 7” non touch. I will plan to upgrade to a 507.

Yes, in my opinion, the GDU 460 operating in split screen mode works as well as two GDU 470 (or GDU 37X) displays for providing information.

The advantage of having 2 GDU 470 displays over 1 GDU 460 display is primarily redundancy. You also have twice the serial ports. Personally, I prefer dual GDU 470 over single GDU 460.

Steve
 
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I think that the 507 supports audio alerts for the autopilot (including a warning that the autopilot has disconnected), while the 307 does not.

This is only significant if you have a G5 system. For a G3X Touch system, the autopilot disconnect and other tones are provided by the PFD.

The GMC 507 also has a TO/GA button discrete input, but again, this is generally only important if you have a G5 based system which would otherwise not have the ability to connect a TO/GA button.

In this G5 system example, the GMC 507 is providing autopilot audio and TO/GA button input capability. Both things the GMC 305 and GMC 307 cannot provide.

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Steve
 
Yes, in my opinion, the GDU 460 operating in split screen mode works as well as two GDU 470 (or GDU 37X) displays for providing information.

The advantage of having 2 GDU 470 displays over 1 GDU 460 display is primarily redundancy. You also have twice the serial ports. Personally, I prefer dual GDU 470 over single GDU 460.

Steve

3 is even better :D

i-29MSXT7-L.jpg
 
GMC 307

For those looking for an easy upgrade path from a GMC 305 to 'knobs', the GMC 307 is actually still available from Garmin - part #010-01595-00.

The GMC 507 has superseded the -307 at the same price and has additional features, so for new installations and G5 standalone autopilot solutions that is the way to go. But, for ease of upgrade from a -305, the -307 is still an option.

Best Regards,

Brad
 
But, for ease of upgrade from a -305, the -307 is still an option.

I did just that just to get the Altitude and Heading select knobs. Also, the two are plug compatible but physically of different size. Going to a -507 would have meant rewiring to use the CANbus.

On my airplane, there is a serial line from the PFD to the 307 and a serial line from the 307 to the roll servo. This means that if the CANbus dies, I still have the ability to control roll with the autopilot. (In my plane, not sure but only the PFD can run the autopilot software. Not sure about the MFD, even in reversion mode, or the G5.) The serial lines are also a backup way for the PFD to access the CANbus, should something strange happen. No idea what backup data paths there are with the 507.

Yes, the 507 does have a TRK button, but... you can access the TRK function throught the PFD touchscreen if you touch the autopilot mode display, and, yes, that's a little clunky. But what's really clunky is that once you select TRK mode, the selected track is not displayed on the chart or map display. You kind of have to sort of remember what you set in. (I've submitted a feature request on that).

There's a lot of functionality, and a necessary amount of complexity, but it all is a chore -- especially if you want to design for and understand backup scenarios.
 
307 v. 507

This is only significant if you have a G5 system.

Correct, that's what I've got. For a G5 system, is there any way to improve the warning from the 307 when the autopilot goes offline? The little flashing A is easy to miss, particularly in an installation where the G5 isn't front and center in the panel. Perhaps the next software upgrade could have it flash the whole screen, for example?
 
For a G5 system, is there any way to improve the warning from the 307 when the autopilot goes offline? The little flashing A is easy to miss, particularly in an installation where the G5 isn't front and center in the panel. Perhaps the next software upgrade could have it flash the whole screen, for example?

Boy, are you winning at stump the chump or what... One very popular avionics supplier got stumped with the two folks I talked to.

There's nothing in FAR 23 that I could find about autopilot disconnect warnings, but I did find AC25.1329-1C, Chapter 3, b.(2), page 16 which says Thou Shalt on aural autopilot disconnects, but that's for transport category aircraft. And it did not specify the three chimes, second button push silences, and one chime for autopilot engagement. I'll let somebody else find that spec!!

So I called Garmin, and for the GMC507, in the G5 Installation Manual, Page C-6, Connector J7001, Pins 13 and 14, are AUDIO HI and AUDIO LO, respectively. The GMC305/7 don't have audio output, although there are three reserved pins. That's as of installation manual Rev AN from March, 2021.

Maybe a feature request for Garmin if you send it in to [email protected]
 
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If it were me I would do like Ed and just upgrade the 305 to a 307 and be done with it. Everything is already wired and ready to go. You really don't want to have to dig into wire bundles and re-wire things just to get a Track button. Especially having to abandon RS232 runs all the way to a servo and then splicing into the CAN Bus. The 507 does have one channel of RS232 pins but I don't think they can be used to talk directly to a servo as the CAN Bus takes over. Steve did the upgrade to 507 but he is an expert and does this kind of stuff for a living and is the best at it. This kind of swap out is second nature for him. You might think hard about it. Unless.... you love doing this kind of stuff and get your kicks out of small incremental upgrades regardless of effort. Like me.
 
CAN bus

On my airplane, there is a serial line from the PFD to the 307 and a serial line from the 307 to the roll servo. This means that if the CANbus dies, I still have the ability to control roll with the autopilot. (In my plane, not sure but only the PFD can run the autopilot software. Not sure about the MFD, even in reversion mode, or the G5.)

If you were to have a total CAN bus failure, the servos are no longer able to communicate with the ADAHRS, the autopilot would be inop and unavailable for lateral control. The ADAHRS and EIS should have a backup RS232 connection made to the GDU, so even with the loss of the autopilot in a CAN bus failure mode, critical flight information would still be available.

Also, you can turn a track vector on using these commands: On the map screen, Menu > Set Up Map > Line > Track Vector

Thanks,

Justin
 
AFCS Controls

Yes, the 507 does have a TRK button, but... you can access the TRK function throught the PFD touchscreen if you touch the autopilot mode display, and, yes, that's a little clunky.

Also on this one, if you do not have a GMC 507, you can access the autopilot mode controls by touching the AFCS mode annunciator on the PFD as you mention, or by pressing MENU twice, and selecting Flight Controls. Like many things, this can all be done using knobs and buttons with no touch required.

Thanks,

Justin
 
If you were to have a total CAN bus failure...

Hmm, not sure about that. I've got serial lines from the ADAHRS to the PFD, PFD to the 307 autopilot controller, and from the 307 to the roll servo. I don't know how to test that all the serial connections actually work, nor that the whole sequence will work in the event of CANbus failure, but when we wired it all up, I was led to believe that I would have limited autopilot functionality in the event of CANbus failure. Wouldn't be able to use the GTN for IFR navigation but at least the PFD has a GPS antenna.

Corrections welcome! Thanks.
 
CAN Failure

Hmm, not sure about that. I've got serial lines from the ADAHRS to the PFD, PFD to the 307 autopilot controller, and from the 307 to the roll servo. I don't know how to test that all the serial connections actually work, nor that the whole sequence will work in the event of CANbus failure, but when we wired it all up, I was led to believe that I would have limited autopilot functionality in the event of CANbus failure. Wouldn't be able to use the GTN for IFR navigation but at least the PFD has a GPS antenna.

Corrections welcome! Thanks.

This is incorrect.

The serial connection from the GMC mode controller to the Roll servo provides limited autopilot functionality in the event of a display failure, but provides no backup capabilities in the case of a CAN bus failure. The GMC 507 does not require a serial line to protect against a display failure, because it is already on the CAN bus.

Thanks,

Justin
 
This is incorrect.

The serial connection from the GMC mode controller to the Roll servo provides limited autopilot functionality in the event of a display failure, but provides no backup capabilities in the case of a CAN bus failure. The GMC 507 does not require a serial line to protect against a display failure, because it is already on the CAN bus.

Thanks,

Justin

This brings up an interesting question. I have a 307, G3X and a G5. I don't see any autopilot functionality in the G5 menu. Will the G5 provide AP services in the event of a PFD failure? I had assumed it would. If so, would I use the 307 to control it? Maybe menu options appear if the G5 sees the PFD go away.

Larry
 
G3X Display Failure

This brings up an interesting question. I have a 307, G3X and a G5. I don't see any autopilot functionality in the G5 menu. Will the G5 provide AP services in the event of a PFD failure? I had assumed it would. If so, would I use the 307 to control it? Maybe menu options appear if the G5 sees the PFD go away.

Larry

Hi Larry,

If you lost your G3X PFD, you would retain all autopilot functionality. The Flight Director modes, and AP engagement would be controlled through the GMC 307. There are no FD mode buttons within the G5 like there are in a G3X display, you do need a GMC Mode controller in this case.

Thanks,

Justin
 
Impressive!

That was in the weeds -- very brave of you to ferret out that info!

I actually think a visual alert could be entirely satisfactory, but every GA autopilot I've ever used before now has had a warning tone. Perhaps the manufacturers want to ensure the equipment is useable in transport category aircraft.

Boy, are you winning at stump the chump or what... One very popular avionics supplier got stumped with the two folks I talked to.

There's nothing in FAR 23 that I could find about autopilot disconnect warnings, but I did find AC25.1329-1C, Chapter 3, b.(2), page 16 which says Thou Shalt on aural autopilot disconnects, but that's for transport category aircraft.
 
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