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Dynon - A List of my woes


tevbax

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First, thank you everyone that has helped me out trying to diagnose some of my airplane issues. Airplane is equipped with a D100/ D120 and a D10 in the LH wing. D10 was moved during the OAT replacement, as you cannot get the connector off the D10 without removing one of the securing bolts. Garmin 496 hardwired with a GTX 327.

List of Dynon Issues:
1. HSI does not match GPS. On the ground, EFIS reads "55", dynon reads 72. I believe this is a calibration with true north correct? I think I found the config in the installation manual. 

2. Winds aloft arrow does not appear. I have gone through the DSAB from the EFIS and it gives me the option of 2 OATs - one for the EFIS and one for the EMS. If I choose EFIS, I get a correct outside temp. If I choose EMS, I get a -40C temp. As far as I am aware, I only have one OAT - the one we replaced. I have read in other forums that if the OAT is not configured correctly, the winds aloft arrow will not appear. 

3. Fuel flow. I believe I have isolated this to a bad sender. Power checks out - need to order another one to start seeing fuel flow and fuel computer functions again. I am ASSUMING that the fuel count wheel inside is not moving or has stuck. Fuel pressure is green at 4.5/ 5GPH.

Any DSAB tips or tricks that I am missing? Or, is there a Dynon Wizard in the Wisconsin area? Really looking to put some of these issues to bed and get it configured correctly. 

 

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I can't speak to your other issues, but I've had a devil of a time trying to get my D100 magnetic heading to be correct.  I think the magnetometer is just flaky and prone to error...maybe Dynon has a new or updated one that is different/better.  I know there was a problem with mine that required a modification (removing a resistor IIRC), but I did that and it's still not right. 

My D100 shows a heading up to 10° different from my GPSs & whiskey compass in some directions, after many attempts to re-calibrate.  On some headings it's dead-on, others it's off as I said up to 10°.  Since I don't really use the D100 heading for anything I just leave it be; if ATC asks me to fly a heading I'll do it off the whiskey compass.

Also my winds arrow shows up, but it's WAY wrong.  The direction is often more-or-less correct, but it can be calm outside and the arrow will show 40+ knots, lol.  It's useless IMO.  I leave it up on my D100 for comedic purposes.  I'm not sure if that uses the magnetometer for its calculations; if so that is another thing pointing to a bad magnetometer unit.

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The heading can be calibrated in the system. It does state that the static system is also used for heading, so I don’t know if a static leak can affect it.

I believe to get the winds, it is just an option in the setup menu for what you want displayed. Not sure how the OAT affects it.

Sorry, I know that wasn’t much help, but it’s all I have off the top of my head after reading the user manual recently.
 

My compass and oat seem to be pretty good, but airspeed and winds have been off since I bought it. It seems I always show a pretty good headwind, even if there isn’t one. Probably related to the airspeed showing about 8 knots fast. Since the static port has an “stepped” surface, does anyone know which direction it should be facing and if that would affect my airspeed?
 

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26 minutes ago, Towner said:

Also, the magnetic compass does not align with true north, but magnetic north 

Right.  My whiskey compass and magnetometer should have the same number, they both point to a magnetic and not a true heading.  But my Dynon is often up to 10° off the whiskey compass, which is correct based on GPS confirmation.  Sorry if I didn't make that clear.

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38 minutes ago, Towner said:

I believe to get the winds, it is just an option in the setup menu for what you want displayed. Not sure how the OAT affects it.

I'm not sure how OAT would affect wind speed calculation, unless it somehow uses density altitude to help calculate winds at varying altitude, which I guess might make some sense.

I would think wind speed & direction would be calculated using trigonometry based off GPS ground speed, indicated airspeed, and magnetic bearing vs GPS heading (crab angle).  And maybe it's adjusted for DA as I mentioned above.

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4 hours ago, FlyingMonkey said:

Also my winds arrow shows up, but it's WAY wrong.  The direction is often more-or-less correct, but it can be calm outside and the arrow will show 40+ knots, lol.  It's useless IMO.  I leave it up on my D100 for comedic purposes.  I'm not sure if that uses the magnetometer for its calculations; if so that is another thing pointing to a bad magnetometer unit.

The exagerated wind velocity is due to input error.  IAS and Mag Heading  error both result in winds being wrong.  Think about it a crosswind drift from compass error will result in a false crosswind.  GS and TAS not matching in calm winds result in enough faslse head or tail wind to resolve the difference.

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You require the following components to get a wind speed indicator:

Heading (calibrate with all electronics powered on, AND an updated magnetic intensity calibration within the past 5 years to even get the heading to calibrate properly)

Altitude

Indicated airspeed

OAT (at higher velocities, temperature has a significant effect on airspeed, and since the dynon unit can be installed in aircraft with high speeds, OAT is required)

The above provide a TRUE airspeed and magnetic course. Remember, you gain 2% per 1000 feet over indicated, this is a LOT.

 

You also need:

GPS supplied ground track

GPS supplied ground speed

These two GPS items provide the ground vector to compare against to get wind speed.

 

I can help you go through your configuration to fix these issues but it would be a maintenance call at 85/hr. I have fixed these issues dozens of times.

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On 8/11/2022 at 2:23 PM, Anticept said:

You require the following components to get a wind speed indicator:

Heading (calibrate with all electronics powered on, AND an updated magnetic intensity calibration within the past 5 years to even get the heading to calibrate properly)

Altitude

Indicated airspeed

OAT (at higher velocities, temperature has a significant effect on airspeed, and since the dynon unit can be installed in aircraft with high speeds, OAT is required)

The above provide a TRUE airspeed and magnetic course. Remember, you gain 2% per 1000 feet over indicated, this is a LOT.

 

You also need:

GPS supplied ground track

GPS supplied ground speed

These two GPS items provide the ground vector to compare against to get wind speed.

 

I can help you go through your configuration to fix these issues but it would be a maintenance call at 85/hr. I have fixed these issues dozens of times.

So, fixed my problem the other day. @Anticept I was 2 minutes away from scheduling that call.

In the 496, under setup/ Interface, the data was set on Garmin Data Transfer. I can only assume this was left this way after the last time it had a map update. Anyways, flipped it over to Aviation In/ NMEA &VHF out, and now were back to working! 

After the calibration, Dynon and EFIS now agree on a heading. 

Sensor wiring test fine for the fuel flow, im calling the sensor wheel stuck or bad. Ordering a replacement part for my LSRM to diagnose/ install. That visit to Rainbow in the fall will pay itself off pretty quickly! 




 

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