Fuel Control Switches

Source: DH

Context: The Air India Flight AI171 crash investigation revealed that both engines of a Boeing 787-8 shut down moments after take-off due to an abrupt movement of fuel control switches to the “CUTOFF” position, triggering loss of thrust and a fatal crash.

About Fuel Control Switches:

• What Are Fuel Control Switches?

• Fuel control switches are cockpit levers that regulate the flow of fuel to each engine, enabling engine start-up, shutdown, and emergency actions. On Boeing 787-8 aircraft, these are placed just below the thrust levers, one for each engine. Design: They are spring-loaded and feature a pull-to-unlock mechanism, ensuring deliberate and intentional use. Positions: RUN: Enables normal fuel flow to the engine. CUTOFF: Halts fuel supply, shutting down the engine immediately.

• Fuel control switches are cockpit levers that regulate the flow of fuel to each engine, enabling engine start-up, shutdown, and emergency actions.

• On Boeing 787-8 aircraft, these are placed just below the thrust levers, one for each engine.

• Design: They are spring-loaded and feature a pull-to-unlock mechanism, ensuring deliberate and intentional use.

• Positions: RUN: Enables normal fuel flow to the engine. CUTOFF: Halts fuel supply, shutting down the engine immediately.

• RUN: Enables normal fuel flow to the engine.

• CUTOFF: Halts fuel supply, shutting down the engine immediately.

• Fuel Control Switches Working:

• Startup Sequence: During engine start, pilots first activate a start selector, followed by moving the fuel control switch to RUN, initiating combustion. Normal Operation: In-flight, switches remain on RUN and any movement to CUTOFF cuts fuel and power to the engine. Emergency Use: In-flight faults may require a manual CUTOFF to shut down a failed engine and the system can attempt automatic engine relight when returned to RUN. Fail-safe Mechanism: The switches are connected to redundant power circuits, and valves are designed to close automatically during power loss for safety.

• Startup Sequence: During engine start, pilots first activate a start selector, followed by moving the fuel control switch to RUN, initiating combustion.

• Normal Operation: In-flight, switches remain on RUN and any movement to CUTOFF cuts fuel and power to the engine.

• Emergency Use: In-flight faults may require a manual CUTOFF to shut down a failed engine and the system can attempt automatic engine relight when returned to RUN.

• Fail-safe Mechanism: The switches are connected to redundant power circuits, and valves are designed to close automatically during power loss for safety.

• Key Features and Safety Design:

• Deliberate Action Required: A pilot must lift the switch before toggling, reducing accidental movement risk. Visual Alerts: In emergencies, red lights illuminate the affected switch for clear cockpit visibility. System Redundancy: Each switch has independent wiring and backup power to prevent simultaneous failure.

• Deliberate Action Required: A pilot must lift the switch before toggling, reducing accidental movement risk.

• Visual Alerts: In emergencies, red lights illuminate the affected switch for clear cockpit visibility.

• System Redundancy: Each switch has independent wiring and backup power to prevent simultaneous failure.