FAA Powerplant Written Practice Test

What do hot spots on the tail cone of a turbine engine exhaust usually indicate?

1. Excessive vibration

2. A problem in the combustion section

3. Faulty exhaust valves

4. Cooling system failure

The correct answer is: A problem in the combustion section

Hot spots on the tail cone of a turbine engine exhaust are typically indicative of a problem in the combustion section. This occurs because abnormal combustion can lead to uneven temperatures, resulting in localized overheating. When fuel does not burn properly, it can create areas of concentrated heat which manifest as hot spots on the exhaust components. These hot spots may arise from issues such as incomplete combustion, which can be caused by a range of factors including fuel-air mixture imbalances, malfunctioning fuel injectors, or other combustion-related issues. High temperatures can ultimately lead to damage in the engine by affecting the structural integrity of the exhaust components. The other options may relate to conditions in an engine but do not directly correlate with the phenomenon of hot spots on the tail cone. For instance, excessive vibration might cause wear and fatigue but typically does not generate localized heat in the manner described. Faulty exhaust valves and cooling system failure can cause performance issues or failures, but hot spots are more closely tied to combustion problems where the air-fuel mixture is not correctly ignited or contained.