Which statement best describes the Electronic Flight Control System?

• A. It comprises a single flight computer and mechanical linkages.
• B. It uses two flight control computers, control surface servo actuators, air data and inertial sensors, and includes a built-in test for failure warnings and fault isolation.
• C. It relies solely on pilot input without sensors.
• D. It uses hydraulic-only control without electronic computers.

Answer: (B)

The Electronic Flight Control System is a fly-by-wire arrangement that uses electronic control logic, redundancy, sensor data, and actuators to move the flight surfaces. It relies on two (or more) flight-control computers to run the control laws, providing fail-safety so a single fault won’t leave the aircraft uncontrollable. Real-time data from air data and inertial sensors feed these computers to determine attitude, speed, and motion, and then servo actuators translate the commanded surfaces movements. Built-in test features continually check for faults, issue warnings, and isolate problems so the system can still operate safely even if part of it fails. This combination of multiple computers, sensors, actuators, and self-test capabilities is what sets EFCS apart from purely mechanical or hydraulic-only controls.