Compass 180 deg off

[ryschneider]

I'm not sure what could be causing my Skyview magnetic heading to be 180 degrees off. It is literally point south when heading due north. I have gone through compass calibration both ground and air (multiple times) without success.

I originally installed the system and flew with it for 2 years but recently installed a new Dynon radio panel and intercom. Then upgraded the software to the recent 16.7.6. Is it possible that the compass issue stems from the upgrade?

I have the following Dynon equipment installed:

Dynon SkyView
7.5" Screen
Backup battery 101265-000
EMS SV-EMS-220
ADAHRS SV-ADAHRS
Magnetometer SV-MAG-236
VHF COM 25 kHz Transceiver SV-COM-760
Radio Control Panel - Oledsv-Com-Panel/H
Skyview SV-Intercom-2S
GPS 250 Antenna SV-GPS-250/A

Thank you for any ideas.
Ryan

 

[swatson999]

Is it rotated 180 degrees? Or mirrored?

And you're SURE you didn't change anything else (like the ADAHRS)?

 

[ryschneider]

Thanks swatson,

During the install, I unplugged SV devices from the back of the display and the network hub in order to make room for the radio/intercom cabling, then of course plugged everything back in.

Both the ADAHRS and remote magnetometer are located in the aft and tail sections and I did not touch either component.

I get the message "need compass calibration" after each boot up and I've performed both ground and in flight cals.

Can you expand on "mirrored" ?

 

[GKC Aviation]

Mirrored means it is working correctly, just 180 degrees out, like looking in a mirror.

Have a look in setup, and make sure the magnetometer is seen in the device list, and online.
The ADAHRS module also has an internal magnetometer, which can be reverted to if the MAG-236 magnetometer is not found on the network.
This doesn't explain why you are seeing the reversed headings, but just make sure it's there.

 

[ryschneider]

Thanks GKC,

It's definitely an odd issue. The small RV icon even appears to be flying backwards in the display if that adds any useful info..

I did check the devices originally prior to the software upgrade (pic attached), I'll go back in and get a status with the newer software.

One other item to note, I did look at the GPS signals as well and all looked good.

Ryan

 

[swatson999]

Can you expand on "mirrored" ?

Well, in thinking about the symmetries of a compass, I'm not sure it makes any difference.

 

[swatson999]

Thanks GKC,

It's definitely an odd issue. The small RV icon even appears to be flying backwards in the display if that adds any useful info..

I did check the devices originally prior to the software upgrade (pic attached), I'll go back in and get a status with the newer software.

One other item to note, I did look at the GPS signals as well and all looked good.

Ryan

A screen shot would be nice here. I smell something related to track up/north up.

 

[ryschneider]

I'll try to get out to the hangar this week and gather more data.

 

[swatson999]

Just go fly and try the in-air calibration while you're there.

 

[maartenversteeg]

You mention that you get a message at each bootup that a compass calibration is required. This presumably means that something is going wrong with the compass calibration process (both ground and in air). Maybe this is an indication that the execution of the compass calibration process is either not happening at all or is not successful for some reason. So your compass is never properly calibrated

 

[ryschneider]

You mention that you get a message at each bootup that a compass calibration is required. This presumably means that something is going wrong with the compass calibration process (both ground and in air). Maybe this is an indication that the execution of the compass calibration process is either not happening at all or is not successful for some reason. So your compass is never properly calibrated

Unfortunately it never successfully gets through the compass calibration or at least not with the correct heading. Over the weekend I went through the steps of the ground calibration twice at N, S, E, W headings (waited for the 100%, etc... but was still unsuccessful), then did the inflight cal and with the same results.
Just a few minutes ago I opened a ticket with Dynon support, I'll keep you posted.
Thank you
Ryan

 

[ryschneider]

Unfortunately it never successfully gets through the compass calibration or at least not with the correct heading. Over the weekend I went through the steps of the ground calibration twice at N, S, E, W headings (waited for the 100%, etc... but was still unsuccessful), then did the inflight cal and with the same results.
Just a few minutes ago I opened a ticket with Dynon support, I'll keep you posted.
Thank you
Ryan

Update, found the problem:
After removing the empennage fairing and cross-referencing my January 2019 build log photos with the Dynon SV installation manual, I discovered the issue: the magnetometer cable was pointing aft (backwards). Although the system functioned this way for the past 2+ years of flying, it failed (or began acting erratically) following the software upgrade, which appears to be the root cause. Another self induced problem on my part, not sure how I did that but it has since been corrected.

 

[swatson999]

I'll certainly give you full props for both coming back here to tell us what you found, and to owning up to the error. Kudos!