FAA Powerplant Written Practice Test

What can cause hot spots that may burn a hole in the combustion section liner of a turbine engine?

1. Excessive fuel pressure

2. A misaligned fuel nozzle

3. Low oil levels in the engine

4. Exhaust system leaks

The correct answer is: A misaligned fuel nozzle

A misaligned fuel nozzle can cause hot spots in the combustion section liner of a turbine engine due to improper fuel distribution within the combustion chamber. When the fuel nozzle is misaligned, it can lead to uneven fuel spray patterns and combustion efficiencies. This irregular fuel distribution can create areas where fuel concentration is too high, resulting in excessively hot combustion in those spots. Over time, these high temperatures can erode and weaken the combustion section liner, potentially leading to a hole or serious damage in that critical area. The combustion process relies on precise fuel-air mixing to ensure efficient burning, and any disruption in that balance—such as that caused by a misaligned nozzle—can lead to localized overheating, manifesting as hot spots. Maintaining proper alignment of fuel nozzles is crucial for ensuring that the combustion process remains stable and uniformly distributed, thereby protecting the integrity of the combustion section.