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Garmin G5 HSI Erratic/flaky

tom paul

tom paul

Active Member
I have a Garmin G5 in my panel which has replaced a mechanical DG/HSI.
I was told by the prior owner, who installed the G5, that it is only connected for use as an HSI, not as a PFD.

I am having two issues with it, one of which seems to be getting progressively worse.

One, it often displays an incorrect heading on start up. It may be 100 or more degrees off the mag compass. A reboot of the G5 has always fixed it, until the other day.
Two days ago, I went for a flight to get my oil hot enough to drain, and I almost didn't take off because the G5 was not coming on line at all.
It first booted up displaying no numbers at all. Just a blank periphery where the heading digits should be. Multiple reboots later, it would display numbers, but erratically jump around for a few seconds, eventually settling on a number about 40 degrees off from the mag compass. I fly with an Aera 660 GPS and rarely use the HSI. (I have yet to use the autopilot) so I thought "I don't need the HSI today" but my concern was more about what was behind the issue that might affect other systems that I DO need. I was considering aborting the mission, but I went ahead with the runup in the meantime. Once that was done, the HSI started indicating accurately and no longer jumped around. I flew without issue.

Any thoughts about what might be going on here?

The other issue is that when I pull more than 1.5 G or so, the G5 defaults to PFD mode and has to be reset to HSI mode manually.
This is consistent behavior.

Looking forward to your thoughts. I have yet to contact Garmin, but that is my next move.
 
not enough info here... the most important, any GMU11 Magnetometer installed? Where? Secured? Calibrated?

but that is my next move
Click to expand...
I'd rather do a software update to start with...
 
Dan 57 said:
not enough info here... the most important, any GMU11 Magnetometer installed? Where? Secured? Calibrated?
Click to expand...

Good question. I'll have to ask the guy I bought it from. I admit to having very little understanding of how this is connected, and of avionics systems in general.
Is there something I can easily see to answer that question?
 
Automatic declutter

Enables and disables the automatic change from the HSI page to the PFD page when the aircraft enters an unusual pitch/roll attitude.9.6
Heading Failure Troubleshooting (with GMU 11)
If a Red-X (steady or intermittent) is displayed in the heading field on the G5, check the following while
the aircraft is on the ground:
1. When taxiing, heading performance is susceptible to the presence of magnetic anomalies (metal
buildings, underground steel culverts, steel grates in the ramp, rebar, etc.). Localized sources of
interference on the ground may consistently cause a Red-X to be displayed on the heading in the
same location while taxiing; this is not caused by a failure of the GMU 11 or its calibration.
2. If any new equipment has been installed on the aircraft, conduct the magnetometer interference
test procedure (see Section 8.4.6.5) to see if the new equipment is causing magnetic interference
with the GMU 11.
3. With the G5 in configuration mode, select the Device Information page and verify there is a green
checkmark next to MAG. If there is a Red-X next to MAG, inspect and verify the CAN bus wiring
between the G5 and GMU 11. See the CAN bus troubleshooting steps in Section 2.2.8.
4. If the problem persists, replace the GMU 11 with a known good unit.
 
The G5 reverts to PFD when subject to G's. Bit annoying to me too. I thought mine was malfunctioning also. I called the Garmin guys. It's like a safety thing if you were in an unusual attitude I guess. Don't really like it myself but it's design.
 
tom paul said:
Good question. I'll have to ask the guy I bought it from. I admit to having very little understanding of how this is connected, and of avionics systems in general.
Is there something I can easily see to answer that question?
Click to expand...

That's the key question. I use my as backup HSI. Its only directional info comes from the GPS navigator so it only displays track. My EFIS is where I get the MH from its own magnetometer. If you don't have the GMU-11 installed, I don't think you can get magnetic heading.
 
GMU11 check

tom paul said:
Good question. I'll have to ask the guy I bought it from. I admit to having very little understanding of how this is connected, and of avionics systems in general.
Is there something I can easily see to answer that question?
Click to expand...

The easiest way to check for the presence of a (optional) GMU11 magnetometer is on the configuration page in the G5. The installation manual has the detail for how to do it.

G5 will display magnetic heading if a GMU11 is connected, otherwise it will display GPS track. If you are not moving then there is no track to display so maybe, hopefully, nothing is wrong with the G5.
 
as Paul mentions, the easiest way is to go into config mode.
From the install manual:

8.2 Configuration Mode All of the configuration and calibration procedures in this section are performed in configuration mode. To enter configuration mode, hold down the knob while powering on the G5.

Then select Device Information and see which devices (LRUs) are installed
 

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Auto Declutter

Flyfish said:
The G5 reverts to PFD when subject to G's. Bit annoying to me too. I thought mine was malfunctioning also. I called the Garmin guys. It's like a safety thing if you were in an unusual attitude I guess. Don't really like it myself but it's design.
Click to expand...

This is Auto Declutter activating, you can disable this behavior in configuration mode > Attitude > Automatic Declutter.

Thanks,

Justin
 
Magnetic Heading Issues

tom paul said:
I have a Garmin G5 in my panel which has replaced a mechanical DG/HSI.
I was told by the prior owner, who installed the G5, that it is only connected for use as an HSI, not as a PFD.

I am having two issues with it, one of which seems to be getting progressively worse.

One, it often displays an incorrect heading on start up. It may be 100 or more degrees off the mag compass. A reboot of the G5 has always fixed it, until the other day.
Two days ago, I went for a flight to get my oil hot enough to drain, and I almost didn't take off because the G5 was not coming on line at all.
It first booted up displaying no numbers at all. Just a blank periphery where the heading digits should be. Multiple reboots later, it would display numbers, but erratically jump around for a few seconds, eventually settling on a number about 40 degrees off from the mag compass. I fly with an Aera 660 GPS and rarely use the HSI. (I have yet to use the autopilot) so I thought "I don't need the HSI today" but my concern was more about what was behind the issue that might affect other systems that I DO need. I was considering aborting the mission, but I went ahead with the runup in the meantime. Once that was done, the HSI started indicating accurately and no longer jumped around. I flew without issue.

Any thoughts about what might be going on here?

The other issue is that when I pull more than 1.5 G or so, the G5 defaults to PFD mode and has to be reset to HSI mode manually.
This is consistent behavior.

Looking forward to your thoughts. I have yet to contact Garmin, but that is my next move.
Click to expand...

Please feel free to contact us anytime with these kinds of questions, at [email protected], or 1-866-854-8433.

In this case, we are going to be interested in the datalogs present on the microSD card in the unit, whether the unit passes the magnetic interference test and the specifics of the installation of the GMU 11 (pictures are always very helpful). Between those three items we should be able to get to the bottom of the issue.

Here is a link to the G5 Installation Manual. The procedure for the magnetic interference test starts on page 8-17.

If you have a microSD card in the front slot of the G5, please remove the card from the G5, and copy all files present on the card into an email to [email protected]. The card must be in the unit during a flight to log data, if a card has not been present in the unit up until now, you would need to insert a card and perform a test flight to log data for us to analyze.

You may want to reach out to the previous owner to figure out where the GMU 11 is mounted.

See post above re: Auto Declutter, to resolve the HSI reversion issue.

Thanks,

Justin
 
amazing responses. Thanks all

Much appreciated.
When I get to the airplane next, I do all these tests.
Thanks for the thorough replies.
 
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