Flight Controls - Elevators 
Pitch Control
The pitch control surfaces consist of two elevators and a Stabiliser. A Mach speed trim system operates the stabiliser to improve speed stability.
Elevator
Moving the control column signals hydraulic actuators to move the elevators. Elevator positions are shown on the EICAS status display. Separate pointers indicate the left and right elevator deflection. A full-scale indication corresponds to the maximum elevator deflection.
If one control column should jam, applying significant forward or aft force to the other causes the two columns to override. Pitch control is then available using the free control column path.
Elevator Feel
Two elevator feel systems provide artificial feel forces to the pilots control columns. Mechanical springs provide feel following a loss of the Centre and Right hydraulic systems.
Elevator Asymmetry
AMM
Elevator asymmetry between captain's and first officer's control system is limited at the aft quadrants by an electrical actuator. The actuator uses an electric motor to position a stop which limits the relative motion between the captain's and first officer's aft quadrants. The motor operates in response to an extend or retract discrete from the Stabiliser/Elevator Asymmetry limiter Module (SAM). Switches on the motor output provide signals back to the SAM to indicate if the motor is in the extended or retracted position. The system is operational full time. Asymmetry is limited to 24 degrees at low speeds and 8 degrees at high speeds.
Elevator asymmetry is indicated by the ELEV ASYM EICAS status message.
Fault Indication
AMM
Elevator control system fault monitoring is provided by the Stabiliser/Elevator Asymmetry limiter Module (SAM) and EICAS system. The SAM provides fault monitoring of the elevator/asymmetry limiter actuator.
A PCU monitor system is installed to monitor hydraulic pressure in the Power Control Actuators (PCAs) to detect and warn of an excessive pressure differential (above 1140-1350 psi) between the PCAs (PCA force-fight).
