moespeeds

moespeeds

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Hey guys, last month finally got my RV8 back from the shop. It was a complete rewire - tip to tail, with a G3X/G5/GTN635/GFC500 install. All new everything, coming from an AFS 3500 system.

Right out of the box, I've been having these regular "Heading Miscomp" errors on the G3X. They seem to pop up randomly, will kick the AP into roll/pitch mode, but will just go away in a min or so.

Over the weekend I got a Magnetometer AHARS error shown in the photo shortly after starting my decent on AP. It also resolved itself in a min.

I'm leery to take this thing into real IFR like this, so why did I spend all this money? Installer has been silent on it but I'm so busy with work and flying I've yet to push him.

Magnetometer is in the tail, right where the AFS unit was for years with no problems. Someone in another group suggested the tail is the wrong spot in the 8.

Any ideas?
 

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moespeeds said:
Hey guys, last month finally got my RV8 back from the shop. It was a complete rewire - tip to tail, with a G3X/G5/GTN635/GFC500 install. All new everything, coming from an AFS 3500 system.

Right out of the box, I've been having these regular "Heading Miscomp" errors on the G3X. They seem to pop up randomly, will kick the AP into roll/pitch mode, but will just go away in a min or so.

Over the weekend I got a Magnetometer AHARS error shown in the photo shortly after starting my decent on AP. It also resolved itself in a min.

I'm leery to take this thing into real IFR like this, so why did I spend all this money? Installer has been silent on it but I'm so busy with work and flying I've yet to push him.

Magnetometer is in the tail, right where the AFS unit was for years with no problems. Someone in another group suggested the tail is the wrong spot in the 8.

Any ideas?
Click to expand...
My read on that error msg is that it is seeing magnetic readings that are non typical. Usually that means a ferrous object nearby that has become magnetized. Garmin has you run an interference test during the installation and speculate that the installer figured he knew better than garmin and skipped it. Many people have good luck with the magnetometer installed back there, but not everyone. All sorts of metal back there that could become magnetized. The universal recommendation is to install it out at the wingtip. I suggest running the interference test exactly as prescribed in the G3X installation manual and see if it passes. If it doesn't, you need t o find the metal and degauss it or move the magnetometer.

Larry
 
lr172 said:
My read on that error msg is that it is seeing magnetic readings that are non typical. Usually that means a ferrous object nearby that has become magnetized. Garmin has you run an interference test during the installation and speculate that the installer figured he knew better than garmin and skipped it. Many people have good luck with the magnetometer installed back there, but not everyone. All sorts of metal back there that could become magnetized. The universal recommendation is to install it out at the wingtip. I suggest running the interference test exactly as prescribed in the G3X installation manual and see if it passes. If it doesn't, you need t o find the metal and degauss it or move the magnetometer.

Larry
Click to expand...
Agreed with this, the mag anomoly message you are seeing is due to interference in the vicinity of the unit. This can be caused by the tools used to install the unit, or from a source of interference in the aircraft near the unit. The mag interference test is a great place to start. Do you notice that the message appears during or directly after any specific manuever or procedure?

If you send us one of your flight data logs we can take a look at it for you and offer some further guidance on getting the issue resolved. Please send it to [email protected].

Thanks,
Justin
 
This should go without saying, but since I just ran into this on a recently completed -14, it bears repeating. Perform all the post installation calibration and tests as described in the Intallation Manual revision AV (link -- https://static.garmin.com/pumac/190-01115-01_av.pdf), Section 30.4.7, Page 30-11.

In the subject aircraft the calibration for the G3X and G5 was not completed by the shop, the builder, or the new buyer -- all assumed that this had been done by the prior party.

Edit: the "shop" in the above anecdote was the plug/play panel provider; they would not have any responsibility or ability to do final configuration and required calibration steps.
 
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What prior party would the avionics shop have assumed did it?

They clearly button pushed their way through the AHRS not Calibrated CAS msg.

That’s ordinary.
 
Perform the magnetometer interference test, cycling lighting on and off (strobes, nav even taxi and landing) one never knows where wires are being run. Also perform a controls check. The interference test will display the results right in front of you live so easy to see what the offending circuit or control was. (My guess is the strobe in the tail but easy to verify.)
 
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moespeeds said:
Hey guys, last month finally got my RV8 back from the shop. It was a complete rewire - tip to tail, with a G3X/G5/GTN635/GFC500 install. All new everything, coming from an AFS 3500 system.

Right out of the box, I've been having these regular "Heading Miscomp" errors on the G3X. They seem to pop up randomly, will kick the AP into roll/pitch mode, but will just go away in a min or so.

Over the weekend I got a Magnetometer AHARS error shown in the photo shortly after starting my decent on AP. It also resolved itself in a min.

I'm leery to take this thing into real IFR like this, so why did I spend all this money? Installer has been silent on it but I'm so busy with work and flying I've yet to push him.

Magnetometer is in the tail, right where the AFS unit was for years with no problems. Someone in another group suggested the tail is the wrong spot in the 8.

Any ideas?
Click to expand...
I get this message if I turn on the LED-wig/ wag lights with the engine running.
If I turn them on before engine start, there is no message "Magnetometer AHARS error".
I think this may have something to do with the power wire to the LED being to close to the magnetometer in the wingtip.

Good luck
 
Richard Connell said:
What prior party would the avionics shop have assumed did it?

They clearly button pushed their way through the AHRS not Calibrated CAS msg.

That’s ordinary.
Click to expand...
Good catch of my poor use of the Queen’s English. The Install shop just did a smoke test - made all the red “X’s” go away…
 
bjdecker said:
This should go without saying, but since I just ran into this on a recently completed -14, it bears repeating. Perform all the post installation calibration and tests as described in the Intallation Manual revision AV (link -- https://static.garmin.com/pumac/190-01115-01_av.pdf), Section 30.4.7, Page 30-11.

In the subject aircraft the calibration for the G3X and G5 was not completed by the shop, the builder, or the new buyer -- all assumed that this had been done by the prior party.
Click to expand...
Richard Connell said:
What prior party would the avionics shop have assumed did it?

They clearly button pushed their way through the AHRS not Calibrated CAS msg.

That’s ordinary.
Click to expand...
Just curious, are the above statements throwing the shop under the bus facts, or merely your opinion?
(the OP is from NJ while bj is from Tx and RC is from Australia)
 
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Walt said:
Just curious, are the above statements throwing the shop under the bus facts, or your opinion?
Click to expand...

The "shop" could NOT have performed the installation as it was a drop ship avionics pre-wire package. The "shop" did nothing wrong.
 
bjdecker said:
The "shop" could NOT have performed the installation as it was a drop ship avionics pre-wire package. The "shop" did nothing wrong.
Click to expand...
Thank you for the clarification, if you buy a "panel in a box" then the responsibility for installation, setup and calibration is with the installer.
 
Flew out to the shop yesterday, and they called Garmin while I was there. They said do a pitch/roll calibration, which I opted to do on my own since I didn't want to leave the plane. I'll report back.
 
moespeeds said:
Flew out to the shop yesterday, and they called Garmin while I was there. They said do a pitch/roll calibration, which I opted to do on my own since I didn't want to leave the plane. I'll report back.
Click to expand...

FYI, you'll need to redo the magnetometer calibration after performing the Pitch & Roll calibration (the existing magnetometer calibration will be wiped).

If you're unfamiliar, you'll need to perform the magnetometer calibration in a location well clear of steel buildings, vehicles or steel in the ground (culverts, etc).
 
For what it's worth, a few weeks ago I started getting miscompare errors in my RV-8 (G3X/G5/GTN625) after two years of pretty much trouble-free navigating. I haven't done a lot of testing yet, so maybe it was a solar flare anomaly or the like (or maybe something with the latest firmware upgrade)? I'll watch it closely over the next few weeks and let the OP know if I can add anything relevant to the thread.
 
PandaCub said:
For what it's worth, a few weeks ago I started getting miscompare errors in my RV-8 (G3X/G5/GTN625) after two years of pretty much trouble-free navigating. I haven't done a lot of testing yet, so maybe it was a solar flare anomaly or the like (or maybe something with the latest firmware upgrade)? I'll watch it closely over the next few weeks and let the OP know if I can add anything relevant to the thread.
Click to expand...

If that’s a new occurrence after many trouble free hours I’d probably double check that none of the bolts holding the GSU25 down or any of the thumbscrews on the DSUBs have come loose.
 
Just an update on this, I ran the Magnetometer Interference test, and when I move the elevators it goes off the scale, over 300%. It will have to go back to the installer and the Magnetometer will need to be moved to the wing. Thank you for all the help.
 
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