[Bavafa]

Just wondering if anyone has simulated PDF failure and see if/what works and what doesn't?* This is specially for those who are equipped*with the IFR system?I simulated a PDF failure and the MFD quickly went to the reversionary mode and took the role of PFD but I am not getting coarse guidance from the 650xi.* All communication with the GAD 29 is intact and as I understand it, coarse guidance comes from that so I'm not sure why it is not working and*I am wondering if this is a bug or a design flaw.

 

[mburch]

It might be helpful if you explained what you mean by "coarse guidance"...

 

[Bavafa]

It might be helpful if you explained what you mean by "coarse guidance"...

Sorry, that is a misspelling on my part, I meant the enroute course guide that we get in the HSI.
I also wonder if we should even get the vertical guidance if on a LPV type approach but at this time I don't get anything.

The flight plan disappears in the MFD which became PFD but that is of a less of an issue as the flight plan is still on the 650 but I would have expected to get the lateral and possibly vertical guidance that should be coming from the GAD29

 

[mburch]

If your G3X HSI no longer shows lateral and vertical deviation data from your external GPS navigator upon the removal of RS-232 data, then you have an ARINC 429 configuration or wiring problem.

 

[Bavafa]

If your G3X HSI no longer shows lateral and vertical deviation data from your external GPS navigator upon the removal of RS-232 data, then you have an ARINC 429 configuration or wiring problem.

We checked the configuration and it was verified. In regards to the wiring, since this info comes on the CAN bus and that is working when the PFD is in normal operation, then it indicates no wiring issue. I also don't get any messages on the MFD about GAD29, only message is "Not receiving GPS navigator RS-232 data" which makes sense.

Hence wondering if this has been tested by anyone.

 

[g3xpert]

Missing CDI Information

We checked the configuration and it was verified. In regards to the wiring, since this info comes on the CAN bus and that is working when the PFD is in normal operation, then it indicates no wiring issue. I also don't get any messages on the MFD about GAD29, only message is "Not receiving GPS navigator RS-232 data" which makes sense.

Hence wondering if this has been tested by anyone.

Good Morning Mehrdad,

When the PFD is powered, do you by chance see a yellow VFR indication inside of the HSI?

Thanks,

Justin

 

[Bavafa]

Good Morning Mehrdad,

When the PFD is powered, do you by chance see a yellow VFR indication inside of the HSI?

Thanks,

Justin

Hi Justin,
I don't believe I have seen that and attached is one photo from my PFD while in flight. Please let me know if this does not valid or show you what you need to see.

 

[Bavafa]

Hi Justin,
I flew again over the weekend and confirmed that I do not see a yellow VFR in the HSI. When the PFD is powered on, the MFD displays the course on the HSI just the same as the PFD and do see flight plans.

Hope this is helpful.

 

[lr172]

Just wondering if anyone has simulated PDF failure and see if/what works and what doesn't?* This is specially for those who are equipped*with the IFR system?I simulated a PDF failure and the MFD quickly went to the reversionary mode and took the role of PFD but I am not getting coarse guidance from the 650xi.* All communication with the GAD 29 is intact and as I understand it, coarse guidance comes from that so I'm not sure why it is not working and*I am wondering if this is a bug or a design flaw.

I believe that horizontal CDI guidance comes from the navigators MAPMX RS-232 port (vertical CDI as well as horiz scaling rate comes on Arinc) that is directly connected to the PFD. So, expect that guidance would go away if the PFD is shut down and control reverts to MFD (PFDs Rx port is no longer active and MFD has no such connection). Not sure if that input can also b replicated on the MFD, but suspect it can if ports are available.

 

[Bavafa]

I believe that horizontal CDI guidance comes from the navigators MAPMX RS-232 port (vertical CDI as well as horiz scaling rate comes on Arinc) that is directly connected to the PFD. So, expect that guidance would go away if the PFD is shut down and control reverts to MFD (PFDs Rx port is no longer active and MFD has no such connection). Not sure if that input can also b replicated on the MFD, but suspect it can if ports are available.

Thanks for your feedback on this. My information was that the radio/Nav control come over the MAPMX and flight planning comes over the RS-232 and those are expected to go away, while course guidance should come over the ARINC 429.
It will be great if Justin can confirm this and perhaps replicate this in their own shop to see the behavior.

If confirmed, in my mind, this would be a great weakness in the system which essentially would void the IFR redundancy in such setup.

 

[mburch]

Every properly wired and configured G3X system + IFR GPS I've ever seen will provide valid lateral and vertical deviation via ARINC 429 even if RS-232 data is unavailable. Sounds like you have an issue, or else the description isn't making sense. Suggest you post images.

 

[Bavafa]

Every properly wired and configured G3X system + IFR GPS I've ever seen will provide valid lateral and vertical deviation via ARINC 429 even if RS-232 data is unavailable. Sounds like you have an issue, or else the description isn't making sense. Suggest you post images.

Matt,
Here is my wiring diagram and I confirmed the configuration settings with Garmin support but if you like to see anything in particular, I can go and take a picture.
My question to you and others, do you have such setup and have you verified with your system that it works as expected? Lastly, to clarify this is a 650xi and I know it is suppose to work just like the 650, but I have one other feature (VNAV) that it does not work the same as the original 650 in conjunction with G3X. I don't want to mix the two issues but I am happy to take that conversation separately.

 

[mburch]

People often say "the configuration is correct" but you'll forgive me if I would rather confirm by seeing pictures of all the RS232 and ARINC 429 configuration on your G3X system and GTN, the device list on your G3X system info page showing the status of your navigator and GAD 29, and a picture of what your MFD looks like when your PFD is powered off. At minimum this is what Garmin support should be asking to see.

 

[mburch]

Not what I expected so I need to start investigating as well. I thought the G5 was supposed to take over AP duty.

Not knowing the exact particulars of your installation, this sounds perfectly normal and expected. If your G5, GMC, and servos are all properly connected you only need to press the AP button again to re-engage the autopilot.

 

[Bavafa]

Tom,
Thank you for testing this, it is good to know that yours is working and now you also know what to expect should this ever happen.

All,
I may have jump gun on this and reported it prematurely. Initially, I tested this on a practice approach and noticed the same thing as Tom, my AP got disconnected and the flight plan went away. I did not take time to see what other errors/issues existed and quickly powered the PFD back on so I can finish the approach.
Then I tested it again on the ground paying attention to the message page and CDI, which I was not getting course guidance. I believe since I was in the hanger, the 650 did not have GPS signal to give guidance. I tested it again today by pulling the plane just enough out of the hanger to get a lock on gps position and sure enough everything seemed to be normal in relation to the lateral/vertical guidance. Loaded a GPS approach also give me the vertical guidance.

I am in the middle of my annual and hopefully will be flying in a week or so and then will test this again in the air.

Thanks to all of those who chimed in on the issue and tried to help solve it.

 

[Bavafa]

Tom,
Do you have a 650 or 650xi?

I had a 650 in my old plane and VNAV worked like a charm thru G3x even if the flight source was set to external. In my new 14 which is a 650xi, if the flight plan is set to external on G3X, VNAV is grayed out and won't work unless I change the source to internal. I tried disabling VNAV on 650xi and that did not make any difference. Of course the VNAV works on the 650xi just fine but I like the way G3X does it.

 

[g3xpert]

Datapath Info

My information was that the radio/Nav control come over the MAPMX and flight planning comes over the RS-232 and those are expected to go away, while course guidance should come over the ARINC 429.
It will be great if Justin can confirm this and perhaps replicate this in their own shop to see the behavior.

If confirmed, in my mind, this would be a great weakness in the system which essentially would void the IFR redundancy in such setup.

This is correct, frequency tuning and the magenta flight path are transmitted over RS-232, CDI information is 429. In the absence of 429 data, the serial datapath provides lateral only, unscaled course deviation. The HSI will be flagged VFR in this case, as it is not to be used for IFR navigation (unscaled). In the absence of RS-232 data, CDI data will be available, but frequency tuning and the flight plan information will not.

Thanks,

Justin

 

[Bavafa]

Mehrdad,

I finally checked the G3X VNAV function while on the External navigator (GTN-650) and it is greyed out. I have to switch to internal to use the G3X VNAV.

That is interesting and thanks for checking it. I believe this confirms that it is a configuration issue since my old plane which I still have access to it and time to time fly it, has a 650 and VNAV on G3x works like a charm regardless if it is on external or internal flight plan. The SW is on the latest revision on both device so it is not a version issue.