727 Autopilot Question
Do any tech types or old timers on the 72 have any idea what could cause the autopilot to oscillate in the pitch mode. It occurrs during all phases of flight, but is intermittent. It seems to be precipitated by turbulence. It isn't divergent and the oscillations do not cause any change in altitude-it just won't dampen out. It does seem to be less when the ac is heavier. When the autopilot is disconnected there is no appreciable trim change. It definitely is the elevators and not the stab as it is a quick, small frequency oscillation and the yokes move. Everyone has had a stab at this and no one has been able to solve it yet. Any ideas?