What are common signs of fuel system contamination?

Fuel system contamination is a serious concern that can lead to various operational issues in aircraft engines. The correct answer highlights several indicators that suggest contamination may be present in the fuel system.

Engine roughness is a primary symptom, as contaminants can disrupt the smooth flow of fuel into the combustion chamber, leading to irregular engine performance. This may manifest as vibrations or an unsteady engine operation. Fuel leaks may occur due to degraded seals or components that are compromised by contaminants, indicating a failure in the integrity of the fuel system. Abnormal performance can encompass a variety of issues, such as power loss, unexpected fluctuations in RPM, or difficulty in maintaining stable engine speeds, all of which can stem from fuel that is impure or affected by particles, water, or improper additives.

Other options present potential issues but do not describe signs of contamination effectively. For example, excessive engine temperatures and fuel vaporization could indicate other problems, such as cooling system failures rather than contamination. Increased fuel efficiency and smoother engine operation are also signs of a healthy fuel system, which is the opposite of what contamination would cause. Low fuel pressure and sputtering engines could indicate fuel delivery issues but are less specific to contamination compared to the signs identified in the correct option.