AP74 Track Problem

[JohnWF]

I suspect the problem I have is somehow my fault, but here goes:

AP74 and Dynon D-180 in a Van's RV-12. Altitude hold works fine; heading feature works fine..."Value" knob works to set barometer and heading but I cannot get the TRK or tracking button to lightr up when depressed, and therefore cannot get the a/p to follow as GPS course from a Garmin 396 that has a flight plan loaded. Main "on/off" button works fine, and the disconnect switch drops anythiing selected as it should.

Ideas?

 

[Brantel]

To have your AP follow a GPS flight plan, you must be in NAV mode. TRK is for following a GPS ground track.

That being said, you should be able to press TRK at any time and follow the GPS ground track as long as your airspeed is between the min and max value you have set up.

What does your HSI look like when you are trying to do this? Is it magenta in color? Are you sure that your GPS is talking to the D180? Are you getting the wind arrow etc? Does your course pointer always point to North/360°? (it should not if working correctly).

To fully function, your GPS's Advanced NMEA speed setting must be set to "Normal" and not "Fast". If it is set to FAST, some functions will work and some won't.

Here is a pic of what your HSI should look something like if you have the GPS communicating correctly and you have a waypoint active in a flight plan on the GPS...

If your HSI does not work correctly, neither will the AP.

 

[JohnWF]

Problem resolved; two problems likely. One probably a coaxial cable shield braid shorting GPS data at the ELT (RV-12 specific problem), and the second was Baud rate selection. On the Dynon D180 use this sequence of button pushing:
EFIS/MORE/SETUP/MORE/MORE/MORE/HSI/insure that EFIS/EMS is set to SERIAL/ input is set to NMEA/ BAUD rate to AUTO.

My baud rate was set to 9600; when changed to AUTO everything began working properly.

thanks for suggestions, folks. I appreciate it.

 

[JohnWF]

Everything almost seems OK now, and I get all the magenta characters, and the plane locks on to a flight plan. But it doesn't follow it. I keep getting more and more error as I progress along the path, with corrections seeming to be opposite of what the plane should be doing. That is, instead of slightly turning right to follow the flight plan course, it tends to move further to the left, away from the course. I checked my compass (no compass rose hereabouts) using the centerline of our runway, which I know to be only 1-degree from its nominal number and that is within 2-degrees per the D-180 compass.

I am probably missing something again...your suggestions?

 

[dynonsupport]

Sounds like you are on "Track" not "NAV".

 

[JohnWF]

Thanks, Support....I will try both ways next flight, and you are right, I was using TRK...