How does the Throttle work?

• A. It is a fly-by-wire system with no mechanical connections to the engines.
• B. It uses mechanical cables to engines.
• C. It is a purely mechanical linkage.
• D. It relies on hydraulic linkages.

Answer: (D)

The throttle is not a simple cable to the engines. Moving the Power Control Lever changes hydraulic pressure that drives the engine’s fuel-control system. The engine uses electronic control (FADEC), but the pilot’s input is transmitted as hydraulic signals that adjust the fuel metering valves and thus set thrust. This hydraulic linkage provides precise, high-force control and reliable operation under the harsh conditions of flight, with appropriate fail-safes built into the system.