Which four types of fuel quantity gauging systems are commonly used?

The correct answer identifies the four types of fuel quantity gauging systems as sight gauges, mechanical, electric, and electronic gauges. Each of these systems is integral to accurately measuring fuel levels in various aircraft types.

Sight gauges are among the most traditional methods of gauging fuel and allow visual confirmation of fuel levels directly from the tank; they are particularly useful for small aircraft and simpler fuel systems. Mechanical gauges, which might include float mechanisms, utilize physical movement in response to fuel levels to indicate quantity, where a float rises or falls with the fuel level, often translated into a readable value.

Electric gauges utilize electrical signals to measure fuel levels, commonly using a float and potentiometer system. Changes in the fuel level alter the resistance of the circuit, with the resultant electrical signal displayed on a gauge. Electronic gauges further enhance this principle by employing sophisticated sensors and digital displays, offering more precise measurements and sometimes adding features such as fuel consumption calculations.

Other options include types of systems that may not specifically pertain to standard fuel gauging practices or are less commonly integrated into aircraft fuel measurement systems. For example, hydraulic and pneumatic systems are associated with more generalized mechanical operations rather than specific fuel quantity gauging. Similarly, while digital and analog references may relate to the display methods of