F27 Autopilot "Airspeed hold"
Hello Everybody. I have a question ref the/a F27 Autopilot. It has a control marked "Airspeed" which says that it 'automatically maintains the indicated airspeed'. My question is how does it do that as I see nothing in the airline operations manual and AP diagram in it that links the AP to the engines, only to the elevators and pitch trim on them (plus rudder and ailerons). With that in mind how can the AP 'maintain the indicated ASI' unless it uses the pitch trim which would result in climb or descent which is obviously not wanted. ??
Thanks in advance.