Optical fiber fuel level sensor for aeronautical applications

An optical fiber fuel level sensor for aeronautical applications is developed and tested. The sensor is based on an array of total internal reflection point sensors multiplexed on a single fiber by optical couplers and simultaneously interrogated by an Optical Time Domain Reflectometry approach. Unlike conventional sensors based on total internal reflection, the new design permits to be sensitive to common jet fuels (JetA-1, JP4, JP5, JP7), and also to correctly operate when the sensor is partially or totally exposed to condensed water on the sensor surface. The sensor does not require aircraft calibration or temperature compensation. Experimental results show that an accuracy of ±1.5 mm could be achieved. The sensor is also able to measure the free water level in the fuel tank.