Which type of indicating system is least likely to be affected by fuel viscosity?

The capacitance type indicating system is the least affected by fuel viscosity because it relies on the dielectric constant of the fuel to determine its level. This characteristic is less sensitive to changes in fuel viscosity, as capacitance operates through electrical properties rather than relying on the physical flow or movement of the fuel. The system creates a capacitance measurement that varies based on the fuel's ability to store an electrical charge, which is primarily influenced by its composition and not by its viscosity.

In comparison, mechanical systems can be significantly affected by fuel viscosity because they often involve float mechanisms or other moving parts that may become sluggish or less responsive with changes in the thickness of the fuel. Similarly, pneumatic systems, which utilize air pressure, can also be influenced by viscosity since variations in fuel density can affect how pressure changes are transmitted. Visual systems, which depend on direct observation of fuel levels, might not inherently relate to viscosity, but factors such as the clarity of the fuel or its behavior in certain conditions can still impact visibility and measurement accuracy.

Therefore, capacitance systems maintain consistent accuracy across varying viscosity levels, making them the optimal choice in this context.