THE RELATIONSHIP BETWEEN MICROBIOLIGICAL CONTAMINATION IN WATER PHASE AND FUEL PHASE IN JET FUEL SYSTEMS

摘要

Microbial growth may occur wherever any water accumulates in aviation fuel tanks and systems and it can lead to operational problems. Because it is difficult to keep aircraft fuel tanks completely free of water, IATA recommends microbiological monitoring to ensure systems remain free of contamination. Similarly, guidance from organisations such as JIG and API relating to aviation fuel supply and distribution recommend some extent of microbiological monitoring. These guidance documents generally recommend use of IATA-recommended microbial test kits for detection of microbial contamination in fuel samples. The three most widely used IATA recommended kits are also IP and or ASTM standard methods with designations IP 613/14 / ASTM D7978-14, ASTM D7463-16 and ASTM D8070-16. Each of the kits detects and reports microbial growth in a different way and varies in its approach to testing water phase if present in a sample, for example either testing water and fuel phase combined or testing each phase independently. IATA guidelines provide contamination limit values for each method, for fuel and water phase tests, which are indicative of negligible, moderate or heavy contamination. IATA recommend that every effort is made to recover and test water in tank sump drain samples as water phase samples will provide the best indication of any microbial growth present. JIG, however, recommends that fuel phase samples are tested and that water is first flushed away before taking samples for microbial analysis. This paper reports on work using laboratory simulants and field samples to investigate the correlation between detectable microbial contamination in fuel and water phases. It aims to provide insight into the basis for establishing contamination limit guidelines for fuel phase and water phase samples drawn from fuel tanks.