At Duncan Aviation, we want our customers to be on the forefront of the very serious issue regarding DEF (diesel exhaust fluid) contamination in jet fuel, and the urgent need for education and awareness to mitigate such incidents. Based on industry publications, three events concerning DEF contamination in jet fuel over the past 18 months have plagued our industry. According to the NBAA, two Cessna Citation 550 Twinjets recently received fuel that had been contaminated with DEF. Both flights suffered single-engine flameouts while at cruising altitude, and one of the Citations later lost its second engine while on approach. No injuries were reported.
DEF is a colorless additive used with diesel engines to reduce emissions, and when mistakenly added to jet fuel, can trigger reactions including the formation of crystals that can plug fuel filters and damage other engine components. DEF has a similar appearance to FSII (fuel system icing inhibitor) additives, also known as Prist, but when formed with Jet A, the solution forms non-soluble crystals that can clog aircraft fuel systems and become catastrophic.
DEF and Prist are similar in appearance, so it is imperative that proper precautions are taken to ensure they are not mixed up. Those are:
Pilots should stay with their aircraft during fueling to ensure they know what is being put into their aircraft, and not be afraid to ask questions. A couple of questions you could ask before fueling are:
Here at Duncan Aviation we have specific procedures and guidelines for handling DEF additive.
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