Microbiological Examination of Sludge Samples from the Fuel Tank of the Fueldraulic Power Supply Equipment

In the KSLV-II fueldraulic thrust vector control actuator system, kerosene is used as the working fluid instead of hydraulic oil.Since kerosene is also used for the power supply equipment in ground tests, it is stored in the fuel tank for extended periods.To maintain the cleanliness of the fuel tank, water removal and particle filters are installed in the fluid circulation line.However, during the maintenance in 2024, gel-like sludge was found accumulating on the bottom and walls.The sludge was suspected to contain metabolic byproducts of Hydrocarbon Utilizing Micro-organisms (HUM), widely recognized in the aviation industry.This paper presents the result of microbiological examination conducted on the sludge samples.It identifies the presence of Hormoconis resinae, commonly known as kerosene fungus, and the biofilm components, which are byproducts of HUM.Finally, several practical methods are proposed to prevent contamination caused by kerosene fungus during long-term fuel storage. - . .