FAA Powerplant Written Practice Test

What powers the thrust reverser systems in turbojet and turbofan engines?

1. Electromagnetic systems

2. Hydraulics or pneumatics

3. Mechanical linkages

4. Electric motors

The correct answer is: Hydraulics or pneumatics

The thrust reverser systems in turbojet and turbofan engines primarily use hydraulics or pneumatics to operate. These systems are designed to redirect the engine's thrust forward, helping to slow down the aircraft during landing. Hydraulic systems are preferred because they are capable of exerting significant force in a compact space, necessary for the rapid deployment of thrust reversers. In typical configurations, hydraulic actuators are controlled by the pilot or the aircraft's systems, allowing for quick and efficient deployment. Pneumatic systems may also be utilized in some designs, relying on compressed air to actuate the reversers. This choice of hydraulics or pneumatics ensures reliable operation under varying conditions, providing the necessary power and speed for the thrust reversal mechanism. While electric motors, mechanical linkages, and electromagnetic systems can have their applications in aircraft systems, they are not the primary means for powering thrust reversers in turbojet and turbofan engines. Electric motors may be used in other components, but their use in thrust reverser actuation is less common, mainly because hydraulic systems offer a better power-to-weight ratio and more responsive actuation.