Which feature does the EFCS include to provide fault detection?

• A. External diagnostics only.
• B. Built-in test.
• C. Manual checklists.
• D. Visual inspection.

Answer: (B)

The EFCS uses Built-In Test to provide fault detection. This means there are self-check routines embedded in the system that continuously monitor critical components—sensors, actuators, control computers, and wiring—for anomalies. If a parameter is out of range or a discrepancy appears between channels, the BIT flags a fault, notifies the crew, and can guide the system to a safe degraded or alternate mode to maintain control. This automatic, in-flight capability is what lets the aircraft detect problems without needing external equipment or manual procedures.

External diagnostics require ground equipment and aren’t automatic fault detection during flight. Manual checklists and visual inspections rely on human observation and cannot continuously monitor or identify real-time faults within the EFCS.