Garmin G5 Issues

[BrettD]

Hey there I was hoping to get some guidance. I have dual Garmin G5's with a 430w, gad 29B, and a GMU11 magnetometer and no autopilot.

 

My problem is the G5's magnetic heading disagrees. The attitude indicator is spot on the money and agrees with my compass, but the HSI is always 20 degrees off. It makes it really confusing trying to fly approaches. 

 

Things I have tried include reading through all the manuals, updating to the latest firmware on the G5's, and going through the configuration pages and making sure all of the settings are correct. 

 

Screenshot: Attitude indicator shows the 077 correct heading (matching compass), 430w shows 077 track, and the HSI magically gets 098 from somewhere.

 

I am not sure if anyone had some ideas that I can try to diagnose the issue

Edited Thursday at 04:46 AM by BrettD

[ArtVandelay]

First, has it always been this way, could be an installation issue.

If not, it may need to be serviced, I had a problem where mine wouldn’t sync up altitudes.

Have a avionics shop bench test it.

[Paul Thomas]

The top one is showing your are tracking 77 while the bottom one shows you are on a 98 heading. Apples and oranges.

[dzeleski]

8 hours ago, BrettD said:

Hey there I was hoping to get some guidance. I have dual Garmin G5's with a 430w, gad 29B, and a GMU11 magnetometer and no autopilot.

 

My problem is the G5's magnetic heading disagrees. The attitude indicator is spot on the money and agrees with my compass, but the HSI is always 20 degrees off. It makes it really confusing trying to fly approaches. 

 

Things I have tried include reading through all the manuals, updating to the latest firmware on the G5's, and going through the configuration pages and making sure all of the settings are correct. 

 

Screenshot: Attitude indicator shows the 077 correct heading (matching compass), 430w shows 077 track, and the HSI magically gets 098 from somewhere.

 

I am not sure if anyone had some ideas that I can try to diagnose the issue

If you pull a fuse on the AI does the DG fail over?

When you do the calibration you do it on the Number 1 "strapped" G5. Generally thats the AI. Its possible the process was not completed correctly or at all.

Page 28 is 7.5.3 for calibration.

https://static.garmin.com/pumac/190-01112-11_03.pdf

That being said this probably needs to go back to an avionics shop.

Edit:

Wait.... TRK and HDG are not the same thing. Is your TRK always matching to the AI heading? That might mean the AI is not connected to the GMU-11 correctly and is just showing TRK as that is all it has access too.

Page 10 5.1.4 explains how to troubleshoot. If you go into config mode -> device information, you might see a red X on MAG.

Edited Thursday at 01:46 PM by dzeleski

[BrettD]

3 hours ago, dzeleski said:

If you pull a fuse on the AI does the DG fail over?

When you do the calibration you do it on the Number 1 "strapped" G5. Generally thats the AI. Its possible the process was not completed correctly or at all.

Page 28 is 7.5.3 for calibration.

https://static.garmin.com/pumac/190-01112-11_03.pdf

That being said this probably needs to go back to an avionics shop.

Edit:

Wait.... TRK and HDG are not the same thing. Is your TRK always matching to the AI heading? That might mean the AI is not connected to the GMU-11 correctly and is just showing TRK as that is all it has access too.

Page 10 5.1.4 explains how to troubleshoot. If you go into config mode -> device information, you might see a red X on MAG.

Thanks for the thoughts... The track seems to always be wrong if that makes sense. I would think if the magnetometer was mis-calibrated then the attitude indicator would show a wrong heading(it is correct) but maybe I am missing something.

 

The other day I was flying a 110 heading in light wind for like 5 minutes and the track was 130 on the attitude indicator the whole time.

 

In the photo I sent the heading shows 077, the garmin 430w track shows 077, but the HSI magically shows 098... I don't even know where that number is coming from. 

 

 

Edited Thursday at 04:48 PM by BrettD

[dzeleski]

1 hour ago, BrettD said:

Thanks for the thoughts... The track seems to always be wrong if that makes sense. I would think if the magnetometer was mis-calibrated then the attitude indicator would show a wrong heading(it is correct) but maybe I am missing something.

 

The other day I was flying a 110 heading in light wind for like 5 minutes and the track was 130 on the attitude indicator the whole time.

 

In the photo I sent the heading shows 077, the garmin 430w track shows 077, but the HSI magically shows 098... I don't even know where that number is coming from. 

 

 

Track and Heading are two different things. Does the HSI 098 match your compass on the glare shield? Track is a GPS path over the ground. Heading is where the nose is pointed too, the difference between the two is your wind correction.

Seeing your GPS track match the AI to me means your AI is using Track because it does not see the Magnetometer so its just defaulting to Track rather then displaying heading. If it was configured to use the magnetometer and it failed you would see a red X and then it would show track as a default.

If your HSI matches your Compass then the HSI is correct and the AI is either misconfigured or something is not connected correctly.

[BrettD]

18 minutes ago, dzeleski said:

Track and Heading are two different things. Does the HSI 098 match your compass on the glare shield? Track is a GPS path over the ground. Heading is where the nose is pointed too, the difference between the two is your wind correction.

Seeing your GPS track match the AI to me means your AI is using Track because it does not see the Magnetometer so its just defaulting to Track rather then displaying heading. If it was configured to use the magnetometer and it failed you would see a red X and then it would show track as a default.

If your HSI matches your Compass then the HSI is correct and the AI is either misconfigured or something is not connected correctly.

Thanks... I might try to pull some circuit breakers when I get a chance and see if I can diagnose it any further. That might help me figure out where the HSI is getting its data from.

[EricJ]

1 hour ago, BrettD said:

Thanks... I might try to pull some circuit breakers when I get a chance and see if I can diagnose it any further. That might help me figure out where the HSI is getting its data from.

The HSI should be getting heading from the GMU11 magnetometer.    There is a calibration process in the installation manual for the G5 to properly align the GMU11, similar to swinging a compass.   Track will be determined from GPS data, either a nav unit or the internal GPS in the G5.