The Elevators are at the aft of the aircraft and are controlling surfaces that alter the pitch of the aircraft (nose up and nose down) for a short-term input. Short term is used at times such as take-off rotation or descending.
Long term pitch is controlled by the stabiliser which is what the elevators are attached to – the stabiliser moves to maintain the aircraft flight profile with changing centre of gravity caused by burning off fuel for example.
The pilot controls the elevators manually and the autopilot system controls them automatically.
The pilot moves the control column forward or aft to control the pitch attitude of the airplane. The control column gives a mechanical input to the elevator power control unit (PCU) through cables and linkages to the input torque tube. The input to the elevator PCUs that use hydraulic pressure to mechanically move the elevator through the output torque tube.
When you engage the autopilot, the autopilot system uses FCC (Flight Control Computers) inputs to control the autopilot actuators. When the autopilot actuators move, they give a mechanical input to the elevator PCUs.
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