Flight Control Systems Overview

Flight Control Systems

• Jacks: The jacks follow surface movement (damping) and are hydraulically retained in the neutral position (centering). One jack is active, the other damped during normal operation. Maneuvers can switch the second jack to active mode. If one jack fails, the other takes over, failing one automatically switching to damping mode. If neither is electrically or hydraulically controlled, both switch to centering or damping mode as appropriate.

• Elevator Deflection Limits: To prevent excessive stress on the tailplane and fuselage, deflection of the remaining elevator is limited if one fails.

• Stabilizer Control: The stabilizer is driven by a screwjack powered by two hydraulic motors controlled by: electric motors (three options) or the mechanical trim wheel.

• Control Surfaces: Pitch control is handled by two elevators and a Trimmable Horizontal Stabilizer (THS).

• Deflection Limits (Control Surfaces): Elevators - 30° nose up, 17° nose down; THS - 13.5° nose up, 4° nose down.

• Electrical Control: ELAC2 normally controls elevators and THS. Green and yellow hydraulic jacks power the left and right elevators, respectively. One of three electric motors drives the THS.

• Failure Modes: If ELAC2 fails, control shifts to ELAC1. If both ELACs fail, control transfers to SEC1 or SEC2 based on available hydraulic systems. The THS motor reconfigures in case of failure.

Flight Control Data Concentrators (FCDCs)

• Function: FCDCs acquire data from ELACs (Elevator Aileron Computers) and SECs (Spoilers Elevator Computers) concerning flight control surface positions and relevant parameters.

• Data Transmission: FCDCs transmit this data to the Electronic Instrument System (EIS) and Centralized Fault Display System (CFDS).

• EIS (Electronic Instrument System): Displays critical flight information (airspeed, altitude, engine parameters) to pilots.

• CFDS (Centralized Fault Display System): Monitors aircraft systems for faults and alerts pilots to issues.

Pilot Controls

• Sidesticks: Independent pilot controls for pitch and roll.

• Rudder Pedals: Interconnected pedals controlling yaw.

• Speed Brake Lever: Deploys speed brakes to increase drag.

• Trimmable Horizontal Stabilizer Handwheels: Adjust the stabilizer for trim to maintain desired pitch attitude.

FADEC (Full Authority Digital Engine Control) System

• Functions: Controls gas generators, protects against engine exceeding limits, manages power, and automatically and manually starts engines.

• Redundancy: Two-channel redundancy.

• Power Source: Magnetic alternator for internal power source.

• Location: Mounted on the fan case.

• Interface: Engine Interface Unit (EIU).

Aircraft Control Systems

• Fly-by-wire System: Pilot inputs are managed by computer control.

• Control Surfaces: Ailerons, Elevators, Rudder, Spoilers, Stabilizer.

• Hydraulic Systems: Green, yellow, and blue hydraulic systems with failure modes and redundancy.

• Electrical Systems: AC and DC power sources, circuit breakers, and fuses.

• Other Systems: Pneumatic, Fuel, Environmental Control Systems (ECS), autopilot, and warning/caution systems.

This quiz focuses on the fundamentals of flight control systems, including the operation and limitations of components such as jacks, elevators, and stabilizer controls. Test your knowledge of how these systems work together to maintain aircraft stability and performance.