Aircraft Fuel Quantity Indication Systems

Posted on February 18, 2022 linda strong avionics

In order to carry out safe and efficient flight operations, it is crucial that pilots have the ability to properly track the amount of fuel that is on board. While a vehicle such as an automobile could simply pull off a road and stop in the case that it runs out of fuel, such safe stops are not possible for aircraft due to their airborne operation and average speeds. As aircraft may vary in the amount of fuel tanks they have, the placement of their tanks, and the general design of the fuel system, fuel quantity measurement must be accurate and accommodate for the construction of the aircraft. In this blog, we will discuss fuel quantity indication systems, allowing you to better understand how they are designed and how they function.

Fuel quantity indicator often range in their complexity to accommodate different systems, their design ranging from simplistic, unpowered indicators to advanced, electronic capacitance types. Direct reading indicators are the most simplistic variations, and they are only used on aircraft where there is little distance between the cockpit and fuel tanks. Meanwhile, larger aircraft will require electric indicators for the means of accurately monitoring aviation fuel from a distance. Generally, the distance of fuel tanks will depend on the size of the fuselage, whether tanks are within aircraft wings or other areas, and other such factors.

In order for fuel within a tank to be measured, there needs to be some sort of tool placed within the fluids. Sight glasses are a common option, coming in the form of glass or plastic tubes that are placed within fuel tanks so that they are filled to the same level as the tank. With a connection to cockpit gauges, pilots can monitor the amount of fuel left in the tank in terms of gallons or fractions of a tank. Another common tool that is used to track fuel is the float and indicating rod assembly, and the float is placed within the fuel while the rod extends through the fuel cap. Due to the buoyancy of the float, it will rest atop fuel and bob up and down as fuel is spent. With its connection to the rod, fuel levels can be relayed to the pilot for ample tracking.

As aircraft have continued to become more advanced, most mechanical fuel quantity indication systems have become more electric in design. Most electric fuel quantity indicators utilize direct current (DC) for their powering and take advantage of a circuit’s variable resistance to drive ratiometer-type indicators. Such devices utilize a type of float, though the connecting arm attaches to a variable resistor’s wiper so that changes in current cause a measurement to be created. Digital instruments such as this are common to aircraft with glass cockpits, and they are fairly reliable. Beyond such examples, some aircraft may take advantage of very advanced systems that are devoid of moving parts.

Whether you are interested in procuring a simple fuel quantity indication system or a robust, electronic indicator, the experts at Aviation Sourcing Solutions can help you secure all that you are looking for with time and cost savings. With over 2 billion items readily available for purchase, we can help you fulfill all your operational needs with ease, and our team members are always on standby to assist customers with quotes for their comparisons. Take advantage of our RFQ services today to receive customized solutions to your needs and see why customers steadily rely on Aviation Sourcing Solutions for all their operational requirements.

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