June 7, 2023

The FAA recently revised a Safety Alert for Operators (SAFO) on jet fuel contaminated with diesel exhaust fuel (DEF).

SAFO 18015R1 highlights four cases in which jet fuel was contaminated with DEF after being confused with fuel system icing inhibitor (FSII), known more commonly by brand names Prist and Dice.

A more recent case not detailed in the revised SAFO occurred in an aircraft departing out of Nevada’s Harry Reid International Airport (LAS) after uplifting 680 gallons of contaminated Jet A.

“Fortunately, these cases of contaminated fuel have not resulted in an aircraft accident,” said Mark Larsen, CAM, NBAA’s director of safety and flight operations. “However, these events have come too close for comfort and are preventable with proper policies, procedures and training.”

DEF and FSII are both clear fluids. FSII is used to mitigate the risk of water within jet fuel to freeze when the aircraft is at altitude and to prevent microbial growth in aircraft fuel tanks. DEF is not a fuel additive and is typically capped with a blue colored cap.

DEF, when mixed with jet fuel, forms crystalline deposits that are insoluble in fuel causing accumulation on filters, fuel metering components, other fuel system components or engine fuel nozzles.

The FAA advises aircraft operators to immediately inform the fueler after discovering DEF-contaminated fuel and then contact their OEM to develop inspection techniques and maintenance actions appropriate for each specific aircraft model type. DEF-contaminated fuel should be discarded and not used in any aircraft or other vehicle.

FBOs should develop policies and procedures to prevent mistaking FSII for DEF and provide personnel training on these policies and procedures. Fuelers should also discard contaminated fuel and notify customers who might have received contaminated fuel.

Review the revised SAFO 18015R1.