Fellow Builders,

 

I have just solved a problem—probably obvious to everyone but me—that has kept my Chelton EFIS from driving my TruTrak autopilot since we first started flying in June. Just in case there’s someone else with my minimal understanding of how this all works together, here’s my situation, and fix.

 

My Chelton EFIS Sport and TruTrak Digiflight autopilot each worked well independently, but would not “couple” to provide an EFIS-directed flight path. My Chelton EFIS installation manual directs on page 99, System User Program Settings (Manual 64-000038, Rev C), that COM9 Flight Plan Transmit be “DISABLED.” The detailed explanation on page 101 indicates some uses of this signal, but fails to note that one use is transmission of flight plan information to the TruTrak Autopilot (if wired IAW the diagram on page 66). Switching COM9 Flight Plan Transmit to “ENABLED” generated the missing “data good” signal on the TruTrak autopilot, and caused the two systems to share both vertical and horizontal flight path guidance.

 

If you have this equipment configuration in your airplane, recommend you change the software switch for COM9 to ENABLED by following the instructions in the Chelton installation manual. I’d suggest you also annotate page 99 of your manual with this change, and add an appropriate note to the explanation of COM9 uses on page 101. It sure made a big difference in how my system works!

 

Bob