Microbiological contamination in aircraft fuel tanks

Microbiological contamination of fuels can cause major problems for aircraft operational use. The most common problems are corrosion of metallic structures, fuel quantity indication problems, blockade of scavenge system and fuel filters and sludge formation1,2,4. These problems cause huge economic burden for air traffic. The sources of microbiological contamination are different kind of microbes such bacteria, fungi and yeast. These microbes live in water which can be introduced to fuel for example by changes in relative humanity or failure in fuel handling procedures1,4. Microbes live most usually in water-fuel interface on the bottom surface of the tank, but they can be detected also in vertical surfaces of the tank and convex shapes such as pipelines1,3.

Aircraft fuel tanks are routinely monitored for microbiological contamination. IATA (International Air Transport Association) recommends fuel tank monitoring depending on location and experience, but at least once in a year1. Easicult TTC and Hygicult Y&F (Easicult M) are semi-quantitative dipslide tests which can be used for contamination monitoring from the fuel water phase. Easicult TTC detects bacteria and Hygicult Y&F (Easicult M) detects yeast and moulds. Tests are based on conventional colony forming unit (CFU) method which is one of the IATA’s accepted methods for contamination monitoring.

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Easicult tests


  1. IATA FUEL BOOK, Guidance Material on Microbiological Contamination in Aircraft Fuel Tanks, 5rd edition,2015
  2. Passman RJ, Fuel and Fuel System Microbiology-Fundametals, Diagnosis, and Contamination Control, ASTM International,USA, 2003
  3. W. Siegert. Microbial contamination in diesel fuel – are new problems arising from biodiesel blends? R.E. Morris (Ed.), Proceedings of the 11th International Conference on the Stability and Handling of Liquid Fuels; 18–22 October 2009, Czech Republic, Prague ,2009
  4. Glaylarde CC, Bento FM, Kelley J. “Microbial contamination of stored hydrocarbon fuels and its control” Revista de Microbiologia 1999;30:10-10

Published August 3, 2016. Edited November 1, 2023.