An Analysis of Microbial Contamination in Military Aviation Fuel Systems

Military aviation fuel systems can be an ideal environment for microorganisms. Microbial growth in hydrocarbon fuel systems arises because of the impracticality of keeping fuel tanks sterile and the inevitable presence of water from condensation. Microbial contaminants in aviation fuel systems are a concern because of their potential to degrade the fuel, accelerate tank corrosion, and threaten flight safety. This research addresses the concern of using more environmentally friendly Fuel System Icing Inhibitors (FSII), which are also biocidal. Are significant levels of microorganisms growing in military aviation fuel systems, and if so, are there any common variables? Forty aviation fuel samples were collected from fuel storage tanks (including flexible expeditionary fuel bladders), refueling trucks, and aircraft from 12 U,S, military bases. Samples were analyzed using peak naming and pattern recognition algorithms of sample extracts processed on a gas chromatograph. Significant levels of microorganisms were found in military aviation fuel systems 90% (36 of 40) of fuel samples produced microbial growth. Over 40% of the serial dilutions that produced microbial growth were characterized as moderately or heavily contaminated samples. The microorganisms isolated were overwhelmingly Gram negative, anaerobic, bacilli with populations varying by orders of magnitude. The original document contains color images.