stec-30

When an aircraft gets upgraded avionics like a GPS, autopilot, and electronic flight instruments in a mid 1970s aircraft for example; is an aircraft flight manual supplement required and must it be printed and carried along with the aircraft or can it be in digital format? Same with the required...

I have an issue with my STEC-30 AP on which I was hoping someone might have some insight. Issue: Works fine in NAV, GPSS, and steer mode. Follows the GPS magenta in lo and high threshold modes appropriately. On HDG mode, however, about 6 months ago, it began flying 10 degrees to the LEFT of...