Problem With AHRS (Align?)

[RayMc]

I'm not sure if this is the correct place for this post, if not please move it to a more appropriate spot.

I have experienced a rather disconcerting problem with my RV-12 recently. On shorter flights of around 2 hours or less everything is great but when the flight gets somewhere over 2 -3ish hours the display will randomly display AHRS ALIGN and disconnect the autopilot.
On one flight with Auto following the magenta line, straight and level, the autopilot began a very tiny, almost undetectable, wing rock left and right for several minutes. Then suddenly I heard a "Bank Angle" annunciation followed by the autopilot attempting a HARD LEFT turn. First I counteracted the turn and simultaneously hit the autopilot disconnect button. The G3X touch showed that it thought I was in an approximate 90 degree right bank! Letting go of the AP Disco caused the AP to attempt the left turn again,
as it should when banking over 45 degrees. After 10 to 20 seconds the G3X began leveling out and I was able to get the phone out for a picture. In the first pic you can see the aircraft is relatively straight and level out the window but the AI still showing about 11 deg. right bank.
I wish I could have taken a pic. with the whole display showing the HARD right bank... quite impressive in synthetic vision, not to mention moderately disturbing!

My RV-12 (ELSA) is my first glass cockpit so I'm still learning about them. Any help or insight is very much appreciated. Aircraft is still relatively new, just clicked over 70 hours.
If it matters the panel has all the bells and whistles, dual G3X Touch displays and Garmin GTN 650Xi Navigator, and XM weather receiver, It is the Experimental version of the RV-12iS-T. (IFR Trainer)

 

[PhatRV]

I had the similar issues with my Dynon ADHARS. I realize you have the Garmin setup. For my case the Dynon support suspect it was due to poor GPS reception. It wasn't the case. Further diagnostic pointed to the ADHARS unit that had failed. This unit had failed before the plane had taken flight. Your unit and my unit behaved as though they are in partial panel situation.

Check the wiring to your GPS and contact Garmin tech support.

 

[mburch]

Take a look at:

SB-00028 - Van's Aircraft Total Performance RV Kit Planes

Directs owners of aircraft with certain G3X avionics kits to assess ADAHRS performance and install isolators on aircraft where issues are observed.

www.vansaircraft.com

(2022) Service Alert 2144 Rev B: Noise Induced Erroneous Attitude | Garmin Customer Support

Garmin Support Center is where you will find answers to frequently asked questions and resources to help with all of your Garmin products.

support.garmin.com

 

[RayMc]

Yet another SB! I should have suspected.

Thank you so much for this information and its rapid delivery, hopefully this will cure the issue.

Ray

 

[RayMc]

Yet another SB! I should have suspected.

Thank you so much for this information and its rapid delivery, hopefully this will cure the issue.

Ray

I talked with Van's builder support, twice, the first guy informed me that since the part numbers were not listed in the online store that I would have to call the order in and ask the salesperson to check the notes on the SB-00028 and talk to the engineer that had the vibration isolator bushings squirreled away in their desk! This seemed like an odd way to do things to me, but, whatever works! After a few days I finally had the time to make a call to vans, it was after 4 pm and closed! A couple more days went by and I was able to call and talk to someone who found a knowledgeable engineer to talk with me. It seems that the SB-00028 does not work and I need to contact Garmin.

The Garmin expert had me download the flight data files and send in the ones from the specific flights when this problem reared its head. The response was there was no evidence of a "Vibration/Noise" issue, and I was asked to call next time I was at the airport to check on a couple things. Great! Ever try to get in touch with someone by randomly calling their office. Still waiting to hear back from Garmin Expert about a specific time to call at a specific phone number so I don't have to "Hope" I will be able to talk to someone that can actually help with the issue without spending a entire day waiting at the airport.

I have gone flying a couple times just to see if I can duplicate the problem, with limited success. The first time was a flight of 2.8 hours... this issue did not show up. My last flight of 3.0 hours was a perfect flight until the final landing roll out when I noticed the G3X indicating about a 10-15 degree bank to the right while on a level runway!

This last flight made me wonder how that would work out if the ADAHRS decided to tell the autopilot/ESP I was in a 50-90 degree bank while I was in the flare at just above stall speed close to the runway... Imagine "BANK ANGLE" and the stick slamming to one side to correct for a hard bank that wasn't!

 

[Walt]

Just curious if you have a dedicated antenna for the G3X?

 

[FlyingSquirrel]

I talked with Van's builder support, twice, the first guy informed me that since the part numbers were not listed in the online store that I would have to call the order in and ask the salesperson to check the notes on the SB-00028 and talk to the engineer that had the vibration isolator bushings squirreled away in their desk! This seemed like an odd way to do things to me, but, whatever works! After a few days I finally had the time to make a call to vans, it was after 4 pm and closed! A couple more days went by and I was able to call and talk to someone who found a knowledgeable engineer to talk with me. It seems that the SB-00028 does not work and I need to contact Garmin.

The Garmin expert had me download the flight data files and send in the ones from the specific flights when this problem reared its head. The response was there was no evidence of a "Vibration/Noise" issue, and I was asked to call next time I was at the airport to check on a couple things. Great! Ever try to get in touch with someone by randomly calling their office. Still waiting to hear back from Garmin Expert about a specific time to call at a specific phone number so I don't have to "Hope" I will be able to talk to someone that can actually help with the issue without spending a entire day waiting at the airport.

I have gone flying a couple times just to see if I can duplicate the problem, with limited success. The first time was a flight of 2.8 hours... this issue did not show up. My last flight of 3.0 hours was a perfect flight until the final landing roll out when I noticed the G3X indicating about a 10-15 degree bank to the right while on a level runway!

This last flight made me wonder how that would work out if the ADAHRS decided to tell the autopilot/ESP I was in a 50-90 degree bank while I was in the flare at just above stall speed close to the runway... Imagine "BANK ANGLE" and the stick slamming to one side to correct for a hard bank that wasn't!

I talked with Van's builder support, twice, the first guy informed me that since the part numbers were not listed in the online store that I would have to call the order in and ask the salesperson to check the notes on the SB-00028 and talk to the engineer that had the vibration isolator bushings squirreled away in their desk! This seemed like an odd way to do things to me, but, whatever works! After a few days I finally had the time to make a call to vans, it was after 4 pm and closed! A couple more days went by and I was able to call and talk to someone who found a knowledgeable engineer to talk with me. It seems that the SB-00028 does not work and I need to contact Garmin.

The Garmin expert had me download the flight data files and send in the ones from the specific flights when this problem reared its head. The response was there was no evidence of a "Vibration/Noise" issue, and I was asked to call next time I was at the airport to check on a couple things. Great! Ever try to get in touch with someone by randomly calling their office. Still waiting to hear back from Garmin Expert about a specific time to call at a specific phone number so I don't have to "Hope" I will be able to talk to someone that can actually help with the issue without spending a entire day waiting at the airport.

I have gone flying a couple times just to see if I can duplicate the problem, with limited success. The first time was a flight of 2.8 hours... this issue did not show up. My last flight of 3.0 hours was a perfect flight until the final landing roll out when I noticed the G3X indicating about a 10-15 degree bank to the right while on a level runway!

This last flight made me wonder how that would work out if the ADAHRS decided to tell the autopilot/ESP I was in a 50-90 degree bank while I was in the flare at just above stall speed close to the runway... Imagine "BANK ANGLE" and the stick slamming to one side to correct for a hard bank that wasn't!

From my understanding the SB-00028 was issued to solve the mounting / vibration issue for the older GSU25s. Garmin also makes a special run of the GSU25 ADAHRS for the RV-12iS to solve this issue, the -55 variant. The new kits don't have this issue, but depending on when you got it you may need a -55 GSU.

If you email me ([email protected]) the serial number for your GSU25 I can check to see if it is already a -55 or not and work with you to get this resolved.

 

[Burndout11]

I had the exact same issue, mine was a -50 ADAHRS. Went back and forth between Van's and Garmin. Sent Garmin some data logs. Vans would not send me the SB parts because my avionics kit was outside of the SB window. Ultimately Garmin sent me a no cost replacement for a -55 model. Solved my problem, just took a couple weeks. Great customer support from Garmin.

 

[ClayR_9A]

Just something I observed on the picture... It says "no wind data." Is this because the magnetometer isn't reading correctly? (my GRT won't show wind data when the mag isn't working right) Does your real heading agree with what it shows on screen? (I ask because on the first picture it looks like your plane is heading 019 and the bearing to your destination is 327.

 

[RayMc]

Just curious if you have a dedicated antenna for the G3X?

Yes, It has the kit supplied GPS antenna, under the cowl, plugged into the PFD.

I received a reply from G3Xpert with a direct line, and promised a short wait! A few settings to be checked.

 

[RayMc]

Just curious if you have a dedicated antenna for the G3X?

Hey Walt,

I spoke with G3Xpert today and we figured out the G3X Touch was not configured to use the attached antenna... It is now!
I hope this solves the problem, but it may take a while to find out because the prob only shows after 2.5 plus hours of flight. I didn't have time for that long of flight today, but I did go for a short flight to get another flight data file for G3Xpert at her request.

There has been a message on the G3X saying an external GPS source was being used and I thought that was normal since I thought the GTN 650Xi was the main source for navigation. According to G3Xpert the ADAHRS Gets GPS info from the G3X and that smaller GPS antenna that is connected to the back of the G3X is the source that the ADAHRS gets needed info from. As a G3X dummy I had no idea!

Fingers crossed.

 

[RayMc]

From my understanding the SB-00028 was issued to solve the mounting / vibration issue for the older GSU25s. Garmin also makes a special run of the GSU25 ADAHRS for the RV-12iS to solve this issue, the -55 variant. The new kits don't have this issue, but depending on when you got it you may need a -55 GSU.

If you email me ([email protected]) the serial number for your GSU25 I can check to see if it is already a -55 or not and work with you to get this resolved.

Josh,

Thank you for your help with getting the GSU-55 variant. I installed it and re-calibrated. It appears to be working well so far, although I have not had the time for a longer (3+ hour) test flight. Yesterday I was able to get in 2.2 hours and all was rock steady, fingers crossed that it will stay that way when I get weather that allows stretching out the distances and time. I will keep you posted.

 

[RayMc]

Josh,

Thank you for your help with getting the GSU-55 variant. I installed it and re-calibrated. It appears to be working well so far, although I have not had the time for a longer (3+ hour) test flight. Yesterday I was able to get in 2.2 hours and all was rock steady, fingers crossed that it will stay that way when I get weather that allows stretching out the distances and time. I will keep you posted.