FAA Powerplant Written Practice Test

What happens when induction system has sharp bends in a reciprocating engine?

1. Improves air flow

2. Decreases volumetric efficiency

3. Reduces compressor load

4. Enhances combustion

The correct answer is: Decreases volumetric efficiency

When the induction system of a reciprocating engine has sharp bends, it can significantly disrupt the airflow. These bends create areas of turbulence, which can lead to a loss of laminar flow. As the air takes a more convoluted path, the smooth and uninterrupted flow that is ideal for engine performance is compromised. This disruption increases airflow resistance, which in turn impacts the engine's ability to fill its cylinders effectively during the intake stroke. As a result of these restrictions, the engine's volumetric efficiency decreases. Volumetric efficiency refers to the engine's ability to draw in the maximum volume of air required for combustion. When the airflow is hindered by sharp bends, less air is available for the combustion process. This inefficiency can result in reduced power output and overall engine performance. In contrast, options that suggest improvements in airflow, reduced compressor load, or enhanced combustion do not hold true in such scenarios where sharp bends impede the induction flow. The overall performance relies heavily on maintaining a smooth and streamlined airflow into the engine, making the presence of sharp bends counterproductive to optimal operation.