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Diesel Exhaust Fluid Contamination in Jet Fuel

July 2019

1Q2A9867At 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:

  • Containers should be clearly labeled in high detail.
  • Containers should be different in shape and size.
  • DEF and Prist should be stored in separate locations.
  • Containers should have a lock and key.
  • DEF should be handled by supervisors and managers only.
  • Team members should be properly trained on DEF and should receive recurrent training annually.

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:

  • Do you have DEF equipment on base?
  • Do you have a DEF policy?
  • Are you aware of recent DEF incidences?

Here at Duncan Aviation we have specific procedures and guidelines for handling DEF additive.

  • All Locations
    • DEF shall not be purchased in the same or similar quantity of any product that is added to the aircraft.
    • All FBO Services and Vehicle Maintenance team members must have an annual briefing on the dangers and risks involved with using DEF around aircraft.
  • BTL, LNK, and PVU Duncan Aviation Equipment
    • Duncan Aviation owned equipment that requires DEF will be the responsibility of the Vehicle Maintenance department.
    • Any required stock will be maintained solely at the Vehicle Maintenance Facility.
    • Only Vehicle Maintenance employees may add DEF to Duncan Aviation equipment.
  • BTL, LNK, and PVU Customer Equipment
    • Ground fuel customers that require DEF in their equipment will be the responsibility of FBO Services employees.
    • Any required stock will be purchased specifically for the customer and will be stored at the customer’s facility only.
    • Under no circumstances will the customer’s DEF stock be stored on Duncan Aviation property.
  • PVU
    • This product will not be kept at the Duncan Aviation facility.
    • When equipment requires DEF servicing, a member of FBO Leadership will purchase, fill, and dispose of the containers ensuring that we will never have the product in supply on the campus.