FAA Powerplant Written Practice Test

What is the purpose of a normalized turbocharger system used on a small reciprocating aircraft engine?

1. To compress air for better fuel efficiency

2. To compress air to maintain manifold pressure constant

3. To increase engine temperature for better performance

4. To reduce the engine's weight for improved speed

The correct answer is: To compress air to maintain manifold pressure constant

The purpose of a normalized turbocharger system in a small reciprocating aircraft engine is to compress air in order to maintain a constant manifold pressure. This is particularly important as aircraft ascend to higher altitudes where the air density decreases. Without a turbocharger, the engine would experience a drop in power and efficiency due to the thinner air at altitude, which can lead to lower manifold pressures and a reduction in engine performance. By using a normalized turbocharger, the engine can effectively compress the thinner air that is available, thereby keeping the manifold pressure relatively constant and allowing the engine to perform consistently across various altitudes. This results in better overall engine performance and fuel efficiency, as the engine can deliver power more efficiently than it would without the normalization process. The design of the system ensures that as the altitude increases, the turbocharger compensates by providing additional air for combustion, maintaining engine performance throughout the flight profile.