Why will SF50 not hold altitude with autopilot engaged?

Question

Mac 10.14.2, X-Plane 11.31r1, Cirrus SF 50, will not hold altitude with autopilot and alt hold engaged and airspeed 250 IAS at 15000 ft-it hunts and elev trim runs up and down.

Answer 1

Hi think108

I'm not with Laminar Research, just a fellow simmer in the UK and although I can't say why it happens, my Cirrus SF50 does exactly the same thing i.e. it 'porpoises' at speeds of 240 knots and above, whilst on autopilot.

The only way that I've been able to control it, is to reduce the speed down slightly to around 230 knots and after level flight has been achieved, it maintains it perfectly from that point on.

Regards