A probe or a series of probes is used in what kind of fuel quantity indicating system?

The fuel quantity indicating system that uses a probe or a series of probes is based on capacitance. In this system, the probes act as capacitors, where the dielectric constant of the fuel changes the capacitance value depending on the amount of fuel present. As the fuel level rises or falls, the capacitance of the probes is altered, and this change is converted into a readable signal that indicates the fuel quantity.

Capacitance fuel quantity indicating systems are favored for their accuracy and reliability in various operating conditions. They can effectively detect fuel levels in both single and dual-fuel tank systems and are commonly used in modern aircraft due to their precision.

By contrast, electronic systems generally refer to those that may include various technologies such as resistive, capacitive, or ultrasonic methods, not specifically identifying the type of sensing mechanism involved. Hydraulic systems pertain to different applications, focusing on fluid mechanics rather than fuel level indication. Likewise, thermal systems typically measure temperature changes and are not designed for fuel quantity measurement.