How can fuel quality be compromised during storage?

Fuel quality can be compromised during storage primarily through exposure to contaminants. When fuel is stored, it can come into contact with various substances that may degrade its quality. Contaminants such as water, dirt, rust, and microbial growth can all adversely affect the composition and performance of the fuel.

Water, for example, can lead to the formation of microbial life, which can produce sludge or acids harmful to both the fuel and the fuel system. Dirt and rust can cause clogging and wear in fuel lines and filters. Therefore, proper storage practices that minimize contamination are crucial for maintaining fuel quality and ensuring safe operation in aircraft systems.

The other options mentioned involve practices that actually support fuel quality rather than compromise it. Maintaining a stable temperature can help prevent condensation, utilizing high-quality tanks can reduce contamination risks, and using a proper seal can help prevent exposure to external pollutants.