FAA Powerplant Written Practice Test

What is the basic component of a pneumatic starter?

1. Centrifugal blower

2. Axial flow turbine

3. Positive displacement pump

4. Jet engine nozzle

The correct answer is: Axial flow turbine

The basic component of a pneumatic starter is an axial flow turbine. This type of turbine is designed to use compressed air to create rotational energy, which is essential for starting larger engines, especially in jet engines. In a pneumatic starter, high-pressure air is directed into the turbine, where it expands and spins the blades of the turbine. This spinning motion is then transferred to the engine's crankshaft, initiating the start-up process. The use of an axial flow turbine is particularly advantageous due to its efficiency and ability to handle high flow rates of air. In contrast, other components mentioned, like a centrifugal blower or a positive displacement pump, serve different purposes and are not primarily responsible for starting engines. A jet engine nozzle, while it plays a role in directing exhaust gases and generating thrust, does not contribute to the starting mechanism in the way that an axial flow turbine does.