Help with Dynon HDX heading issue

edessa

edessa

Pre-takeoff checklist
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Mar 4, 2014
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Highland Heights, OH
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edessa
A friend upgraded his Mooney to twin 10" Dynon HDX displays and Avidyne 440 GPS navigator.
He is having a heading split between the GPS ground track and the magnetic heading. The GPS is correct and the mag was 40 degrees off. Everything is synced on the ground and only as the aircraft accelerates does it start to split.
I found that the installer installed the ADAHRS unit 16 nose down compared to the remote magnetometer and the aircraft. I corrected the installation within 0.1 degrees and although it improved but there is still a 15 degree split.
I removed any equipment that may cause interference and still no change.
My best guess is that the accelerometer in the ADAHRS unit is bad causing the split as the aircraft accelerates but just a guess.
I know the easy answer is to take it back to the installer. I would like some input as to what could cause the problem other than a bad ADAHRS or Magnetometer units.
I do have video of the split as it happens at takeoff. Pictures also.
Thank you in advance for any help you can provide.
 
I have never seen this. It would be worth trying a different magnetometer and/or adahrs. Make sure you do a good compass cal.
 
Also make absolutely sure that the magnetometer is connected to the network and seen on the Network Status screen. If it is not connected, then the magnetometer in the adahrs is providing heading, which would be very inaccurate close to the engine.
 
Thank you Jesse. We do see the MAG-236 in the network and during calibration. Here is an image from the video I recorded during the flight calibration. it ended at 102%.
I wish there was a description/Operation section with details for the Dynon components so I can fully understand the system and Dynons thinking on the design.99023294-8AE6-4B30-92BF-3FF3F0B480D5.png
 
I would invite you to stop by and we could test a new adahrs and/or magnetometer, but Ohio is a long way from Florida.
 
Yes it is. I tried to convince my buddy to bring it down to you but for some reason he took it somewhere else.
Here is the infor from the Network Status page and PFD source selection page.Screen Shot 2021-10-10 at 10.23.12.png Screen Shot 2021-10-10 at 10.23.32.png
 
I think we will be asking Dynon to send out a MAG-236 and an ADAHRS to replace one at a time and see which one fixes the problem. I will keep everyone posted on the progress.
 
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Clip4 said:
Which is the problem for most people who buy Dynon and have an issue.
Click to expand...

Not sure I understand.

I had a Garmin 430 problem and Garmin said to "take it to a dealer and have him send it to us". Garmin dealer was a couple hundred miles away.

I wanted to have my Dynon HDX screen modified, and Dynon said "send it to us". They modified it and returned it to me a week later. Another time, a piece of hardware was suspect, and they sent a replacement directly to me. Sure, I could have gone to the local avionics shop or even my A&P, and they would have interacted directly with them too.

It sounds like you've had some negative experience with Dynon service, and while the internet is a wonderful place to share good and bad experiences, but it can also be damaging (or helpful) to a company if it isn't based on fact. Do you have some experience with Dynon service?
 
JohnAJohnson said:
Not sure I understand.

I had a Garmin 430 problem and Garmin said to "take it to a dealer and have him send it to us". Garmin dealer was a couple hundred miles away.

I wanted to have my Dynon HDX screen modified, and Dynon said "send it to us". They modified it and returned it to me a week later. Another time, a piece of hardware was suspect, and they sent a replacement directly to me. Sure, I could have gone to the local avionics shop or even my A&P, and they would have interacted directly with them too.

It sounds like you've had some negative experience with Dynon service, and while the internet is a wonderful place to share good and bad experiences, but it can also be damaging (or helpful) to a company if it isn't based on fact. Do you have some experience with Dynon service?
Click to expand...

Wow, 200 miles. For some Dynon customers it would be 800.
 
Everything we had done for troubleshooting is under the direction of Dynon customer support. I think the next step is to start replacing parts.
 
Here are two of the videos I recorded as a pax during flight. You can see the split occur clearly on the second video as the aircraft accelerates for take off. I have the G meter on the second video to see if anything weird is going on with the accelerometer but I have nothing to compare it to.


 
Clip4 said:
Wow, 200 miles. For some Dynon customers it would be 800.
Click to expand...

I don't think you understand. Dynon doesn't force you into their network for assistance, so help can be as close as your own skill set, or your A&P, or your preferred avionics shop. Options are usually better, no?
 
JohnAJohnson said:
Not sure I understand.

I had a Garmin 430 problem and Garmin said to "take it to a dealer and have him send it to us". Garmin dealer was a couple hundred miles away.

I wanted to have my Dynon HDX screen modified, and Dynon said "send it to us". They modified it and returned it to me a week later. Another time, a piece of hardware was suspect, and they sent a replacement directly to me. Sure, I could have gone to the local avionics shop or even my A&P, and they would have interacted directly with them too.

It sounds like you've had some negative experience with Dynon service, and while the internet is a wonderful place to share good and bad experiences, but it can also be damaging (or helpful) to a company if it isn't based on fact. Do you have some experience with Dynon service?
Click to expand...
Unfortunately there’s still folks that insist that the world is flat.. and flying off the edge sends the unexpected traveler off to oblivion.
 
Last edited:
JohnAJohnson said:
I don't think you understand. Dynon doesn't force you into their network for assistance, so help can be as close as your own skill set, or your A&P, or your preferred avionics shop. Options are usually better, no?
Click to expand...

Most pilots and APs have no skill set to trouble shoot and remedy this stuff. The local avionics shop may or may not help you since they are not Dynon dealers and Dynon is cutting them out of the sales chain.

I am not claiming Dynon is a bad product, but the buyer needs to understand things may be more complicated when things are malfunctioning or as you point out, they may be easier.
 
Dynon will be sending out a replacement magnetometer (MAG-236). Will let you know if this fixes it.
Next step will be to move the magnetometer to the wing.
 
Can you please let me know how you fixed the problem. I am having the same issue with another brand of AHRS, but get the erratic heading errors when banking, not in pitch changes.

for what its worth, I initially placed magnetometer in fiberglass wing tip of a c172, but could not get the thing to show constant heading and heading was erratic with engine running. I have been troubleshooting for days now with moving sensor in different positions. I am next going to wrap wire to sensor in tin foil and use small alligator clip to ground the foil on one end to somewhat eliminate any EMI interference….the wire is not shielded. If that works, I’ll replace the wire with shielded jacket.

if the new magnetometer isn’t the issue, suggest not mounting it so you can move it around in flight to see if there is any improvement. Also, the manufacturer of my EFIS, Talos, says the pitch and bank changes in heading will be corrected in flight if the efis box also senses these roll and pitch and roll changes… so they work in tandem, that’s why my heading changed on ground when pitching of rolling magnetometer in my hand, as the EFIS box didn’t detect any changes.

please keep me posted on progress.
 
AlphaPilotFlyer said:
Can you please let me know how you fixed the problem. I am having the same issue with another brand of AHRS, but get the erratic heading errors when banking, not in pitch changes.

for what its worth, I initially placed magnetometer in fiberglass wing tip of a c172, but could not get the thing to show constant heading and heading was erratic with engine running. I have been troubleshooting for days now with moving sensor in different positions. I am next going to wrap wire to sensor in tin foil and use small alligator clip to ground the foil on one end to somewhat eliminate any EMI interference….the wire is not shielded. If that works, I’ll replace the wire with shielded jacket.

if the new magnetometer isn’t the issue, suggest not mounting it so you can move it around in flight to see if there is any improvement. Also, the manufacturer of my EFIS, Talos, says the pitch and bank changes in heading will be corrected in flight if the efis box also senses these roll and pitch and roll changes… so they work in tandem, that’s why my heading changed on ground when pitching of rolling magnetometer in my hand, as the EFIS box didn’t detect any changes.

please keep me posted on progress.
Click to expand...
Still waiting on the magnetometer to come from Dynon. Will definitely report of any changes.
 
Let's run Dynon out of business so Garmin has a true monopoly. Then things will be better for the consumer. /sarc
 
Solved my issue by changing out wire between magnetometer sensor and EFIS box with a braided shielded jacket and grounding one end of shield to known ground. Hope that helps.
 
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