What does "fuel tank expansion" refer to?

The term "fuel tank expansion" refers specifically to the increase in fuel volume due to changes in temperature. This phenomenon occurs because, as the temperature rises, the fuel molecules become more energetic and move apart, leading to an increase in the volume of the fuel.

In aviation, understanding fuel tank expansion is critical for ensuring that fuel systems are designed to accommodate variations in fuel volume caused by temperature fluctuations. This is especially important during flight operations, where temperature can vary significantly with altitude and environmental conditions. Proper management of fuel volume ensures that the fuel system remains effective and that the aircraft operates safely within its design parameters.

Other aspects of fuel systems, such as fuel pressure, fuel weight, and contamination, do not directly relate to the concept of tank expansion in terms of physical changes in volume due to temperature, which is why they do not define "fuel tank expansion."