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Question for D180 drivers

Handclutch

Well Known Member
My aircraft had its annual today along with the annual IFR sign off by the avionics guy. He did a compass swing to calibrate the heading indication in the D180 and also the wet compass. It seemed a fairly imprecise exercise to me but it was the first time I had been involved in a compass swing. There was a lag in the heading indication - not sure if that is normal. When I lined up on 90? for example the indicated heading would change gradually over the next 10 seconds by a few degrees. He didn't seem to be compensating for this but am no expert in the area. On one heading we were over 10? off and he declared the unit unserviceable. He did try a calibration but clearly wasn't familiar with the D180 and I had never done one as the unit was already installed when I bought the aircraft. He wants me to send it back to Dynon. Happy to do that if it's necessary (I'm in Australia, not quite as easy as in the US) but think I will do a full calibration first and seek some further information.

He was also concerned about the ASI reading 20 to 30 knots while stationary. My D180 has always done that. Is it normal? It's never worried me because it is quite accurate in the air right down to the stall. He felt that Dynon would have a fix for it by now.

A further concern was the lack of a usable amp meter. Mine fluctuates wildly which I believe is fairly typical of the D180. Again, he thought Dynon could fix that. My solution for IFR purposes has been to set the low-voltage warning at 13 V. If the generator fails I'm going to know about it straightaway.

Looking for any advice or comment, and thanks in advance.

Jack
 
Read chapter 5 of the d180 install manual. The procedure for calibrating the compass is very detailed and must be done correctly. After i got mine setup, it is very accurate and swings like it should. The asi reading 20-30 on the ground indicates you have something in the sensor. I once got a mud dabber in my pitot tube. It was back in the elbow and could not be seen on preflight. I took off and no airspeed indications. I took the line off and flushed it out with water. My asi read 20-30 on the ground for months. I guess the water finally evaporated out. If you have a speck of something solid in there, it would do the same thing. It did not seem to hurt anything while in there.
 
If you do not have a copy of the D-180 installation guide, DOWNLOAD it.
Compass calibration is described starting on page 5-1.
My ammeter has never worked right either and neither have several others. Even with a jumper across the D-180 ammeter input EMS pins 24 & 25, the display still jumps all over the place. I never bothered to have the D-180 repaired because the voltmeter tells me if the alternator is working or not.
The ammeter display can be turned off. See page 6-15 of the installation guide. Tell the mechanic that there is no ammeter installed.
Page 9-5 describes how to set the airspeed zero-pressure-value.
 
Airspeed should show "0" until fixed threshold is met (I think 25 knots or so) and then airspeed becomes active.

Ammeter on D-180 fluctuates - normal for this unit.
 
Not an RV12 (RV8) but my D180 ammeter is very steady. Perhaps a difference in alternator/regulators?
 
I fixed one plane with D180 compass symptoms just like yours, I re-mounted the remote magnetometer, it was off by 6 degrees in one axis.
 
I have a dual setup with D180 and D100. After setting the MAGINT and MAGINC (I?m working from memory on the titles) values my compass swing is dead on. My D180 reads 0 Kts at rest while my D100 can read 20 Kts, but above 30 Kts the two are within 4 Kts of each other. My altimeter readings also differ by about 20 FT.
 
Software version?

Looking for any advice or comment, and thanks in advance.

Jack

Do you have the latest software version? I seem to recall that updating to the latest software version fixed some compass calibration issues. The original builder should have installed a db9 serial cable connector. You will need a serial to USB cable to do this. Download the Dynon software and follow their installation instructions. Unfortunately it?s only compatible with Windows computers but even a Mac running bootcamp will work.
 
Thanks all.

Airspeed looks to be an easy fix. It was too gusty around the hangar yesterday for a zero pressure adjustment but will get to it today.

Ammeter more of a challenge. I'll check connections on the shunt etc but it seems like fluctuations are quite common. Indication is steady without generator input - when the regulator failed it showed a steady discharge.

I probably haven't got the latest software version. I've had the aircraft five years and haven't updated but the builder did install a plug. Another 'to do'.

Heading is the most important problem to fix. I haven't checked the magnetometer, assuming that if it was installed in accordance with the KAI (confident the builder would have done that) it should be properly aligned. I can't see the actual installation step in the KAI that I have. There is new front page for section 10 stapled in that shows the F-00009 bracket but no detail beyond that.

Next step will be back to basics with with the magnetic inclination and intensity and a new calibration. That has to be done anyway because the way the re-calibration was done ensures it is no longer accurate.

Updates when available.

Jack
 
The RV-12 with the D-180 does not have a conventional shunt. You will not find it because it is integrated
into Van's control board. (assuming that the plane was built with Van's parts and according to plans).
 
Thanks, Joe. It does have a shunt (on the shelf behind the motor and hard to get at) because the electrics were to the builder's own design, not the plans. It uses the circuit breakers, conventional switches and a large junction box. I've had no problems with it and the the layout is easy enough to follow. I've modified the avionics extensively and there's been no problem with integration.

I've just spoken to my mechanic (not the avionics guy) and he made the same suggestion as you - remove the ammeter indication. He says voltage is a much better indicator.

Jack
 
I've has the static airspeed indication show 20kts, it was water in the pitot tube, there was a place where the tubing dipped down, after disconnecting the fittings I blew it out. I had also at another time low indicated airspeed, I had to put aircraft in hanger, cover pitot tube and static ports with a rag (lightly) to create a no wind environment then did a recal in the D180 menu, worked great.
 
"Heading is the most important problem to fix. I haven't checked the magnetometer, assuming that if it was installed in accordance with the KAI (confident the builder would have done that) it should be properly aligned."

The aircraft owner tried to calibrate his compass countless times before he sent his D180 in to be checked over, got it back & assumed it still faulty as symptoms were the same. My task was to remove the unit & re-send it back to Dynon for another go around. Instead, I felt it more important to recheck the component installations, starting at the Magnetometer… a new properly oriented bracket fixed it.

Don't assume
 
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Sorted

There is no problem with the D180, thankfully. Zero pressure reset resolved the airspeed issue and took all of a couple of minutes.

Heading indication was interesting. I flew it on Saturday and it was 10 - 12? out based on runway heading. This definitely wasn't the case before the compass swing. Seems button pushing by the avionics guy (without fully understanding the D180 or reference to the manual) induced the error. Back to basics, resetting the magnetic inclination and intensity, although probably not necessary, and then a re-calibration. Taxiing around the airport showed the heading indication was within 1 to 2? based on info from the 420W. Looked good on the runway and I then flew a few legs of our local GPS approaches including doing one in reverse. Not much wind and all heading indications consistent with expectations, especially when flying the reciprocal track.

Had it checked independently yesterday and now signed back into the IFR world.

Ammeter sleuthing can wait. In the meantime I'll turn off the display - it isn't required under Australian regs.

Thanks for the suggestions and advice.

Jack
 
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