FAA Powerplant Written Practice Test

What causes hot spots that can damage the combustion section liner in a turbine engine?

1. A misaligned fuel nozzle

2. Excess fuel flow

3. Improper cooling of engine components

4. Foreign object damage

The correct answer is: A misaligned fuel nozzle

The correct answer is based on the understanding that a misaligned fuel nozzle can lead to uneven fuel distribution within the combustion chamber. When a fuel nozzle is not properly aligned, it can create localized areas where the fuel-air mixture ignites inefficiently or burns excessively hot. This localized overheating can result in "hot spots," which are areas that experience temperatures significantly higher than the surrounding material. These hot spots can lead to thermal distortion, melting, or even cracking of the combustion section liner, ultimately compromising the integrity and performance of the engine. Proper alignment of the fuel nozzle ensures an even and optimal combustion process, helping to avoid the formation of these damaging hot spots. Considering the other options, excess fuel flow can generally lead to increased overall engine temperature but does not specifically create hot spots related to nozzle alignment. Improper cooling of engine components generally relates to overall engine temperature management rather than specific localized damage caused by fuel nozzle alignment. Foreign object damage typically refers to physical impacts on engine components from external objects rather than issues arising from misalignment or thermal behavior of the fuel system.