Well, that took a minute .......
Steinair strikes again
The worst part about intermittent problems is that they are intermittent. So hard to pin down. Thanks to Tony Kirk for providing clear info on the power circuits but the problem was not there. Many , many hours of frustration was spent on this only to find the problem in another D-Sub not correctly assembled. This is the 3rd such problem with this aircraft that all comes back to what should be one of the most reliable connectors the D-Sub.
You would think that D-Sub assembly 101 would mean you hear a satisfying click when you push the pin into the D-Sub hole and do a pull test to confirm .
This was not the case and for 250 hrs the pin contacted just enough to work until vibration slowly backed out the pin. The most frustrating red herring was that pulling and re-inserting the fuse would re-set the trim and it would work for a bit longer. It was touching just enough.
The discovery happened when from frustration we pulled the Dynon Autopilot module thinking there was a fault there. Several attempts to find the problem then the back shell of the D-sub was disassembled to find the red wire not seated , it was under strain from the heat shrink, this was relieved and the wire was seated.
This was now 25 hrs ago .
Problem solved.
The offending D-Sub being dismantled.
Photo showing red wire not "Clicked " in. The heat shrink was cut back to relieve some strain on the wire and it happily "clicked" back in.
Hoping this may help some other frustrated aviators.
A massive Thank You to David Brown, local Dynon Installer for his clear eyes and persistence, Thank you David !