Aircraft Systems - Flight Controls Overview elevators

Flight control surfaces that control aircraft roll.

Aerodynamic surfaces reducing lift.

Flight control surfaces affecting yaw (side-to-side movement).

Power flight controls by using pressurized liquid.

Power flight control servo systems using electricity.

Manage flight control priorities.

Components (e.g., BCM, BPS) providing fail-safe power/control.

System to reduce the workload, potentially on flight controls.

Elevators can move up to 30° nose up and 15° nose down.

Trimmable Horizontal Stabilizer can move up to 14° nose up and 2° nose down.

PRIM 1 controls elevators and horizontal stabilizer during normal operation.

Activated when PRIM 1 fails; controls elevators and horizontal stabilizer using alternative systems (hydraulic jacks).

Takes over pitch control (elevators) if both PRIM systems fail.

When all three primary pitch control systems (PRIM 1, PRIM 2, and PRIM 3) fail, the secondary pitch control system (SEC 1) becomes the primary and takes over pitch control of the elevators.

In the event of a 3 PRIM failure, the SEC 1 system assumes control of the elevators, ensuring the ability to pitch the aircraft.

Even if the electrical control of the trimmable horizontal stabilizer (THS) is lost, manual control is still possible using the pitch trim wheel.

A 3 PRIM failure leads to a loss of electrical control over the trimmable horizontal stabilizer (THS), but manual control is still possible.

If the electrical control of the THS is lost, the manual pitch trim wheel allows the pilot to adjust the pitch trim of the aircraft.

The trimmable horizontal stabilizer (THS) can be manually controlled using the pitch trim wheel, even if the electrical system fails, as long as either the blue or yellow hydraulic systems are operational.

Mechanical control of the THS from the pitch trim wheel takes precedence over electrical control.

A manual control device used to adjust the trimmable horizontal stabilizer's position, providing pitch stability.

If both the blue and yellow hydraulic systems are working, the pitch trim wheel can manually control the trimmable horizontal stabilizer (THS) even when electrical control is lost.

The pilot's manual control of the THS using the pitch trim wheel is the most important control method, taking precedence over electrical control.

Two hydraulic servojacks control each elevator. One jack is active (electrically controlled), while the other is damped (following surface movement). This configuration provides redundancy in case of a failure.

Each servojack has three modes: Active (electrically controlled), Damping (follows surface movement), Centering (hydraulically maintained in neutral).

If the active servojack fails, the damped jack automatically becomes active, ensuring continued elevator operation. In case of both electrical and hydraulic failure, both jacks go into damping mode.

The stabilizer is driven by a screwjack powered by two hydraulic motors. These motors are controlled by either one of three electric motors or the mechanical trim wheel.

The mechanical control of the stabilizer using the trim wheel takes precedence over electrical control, ensuring a fallback option in case of electrical failure.

When neither jack on the elevators is electrically controlled, both jacks are automatically switched to the centering mode, holding the elevators in a neutral position.

Each elevator jack can be in one of three modes: Active (electrically controlled), Damping (following surface movement), or Centering (hydraulically maintained in neutral).

If the active servojack on an elevator fails, the damped jack automatically becomes active to maintain control, ensuring continued operation.

The pitch trim wheel allows the pilot to directly control the trimmable horizontal stabilizer (THS) position, even if the electrical system fails.

Mechanical control of the THS from the pitch trim wheel overrides electrical control, ensuring a backup option if the electrical systems fail.