[tomcomet]

I have the 400A autopilot and it has been acting up on the last couple of flights. Often it will take 2-3 tries to get it to engage and sometimes when it does engage I will get an elevator trim runaway which sends me into a short lived dive before I hit yoke switch OFF.

Last week it stopped working all together in both HEADING and NAV modes. I tried changing all parameters but no luck. Today as well there was no response from the autopilot apart from a slight stiffening of the yoke control. Heading bug had no effect and there were none of those little robotic whining noises although the HDG button was light green on the FDI and the autopilot switch remained ON. After a minute or so the HDG went back to orange on its own. Bummer...

Any ideas..?