Industry Working Group Report Recommends Ways to Address DEF Contamination of Jet Fuel 
Thursday, June 20, 2019 at 10:48AM
Will Davis in Contamination, DEF, Mitigation Plan, News

Members of the Aircraft Diesel Exhaust Fluid Contamination Working Group have released recommendations for FBOs, aircraft operators and other aviation industry stakeholders to prevent contamination of jet fuel with diesel exhaust fluid (DEF).

DEF crystallizes when mixed with jet fuel. The crystalline deposits can clog fuel system components and filters and lead to engine failure. Since November 2017, DEF has been confused with fuel system icing inhibitor (FSII) on three separate occasions at three different U.S. airports, according to the working group’s report. The most recent event on May 9 this year led to engine flameouts on two Cessna Citation 550s operated by a Part 135 operator.

The working group advises the adoption of its short-term and long-term mitigation plans, based on prevention of DEF contamination, detection of contamination and preparation for response to contamination.


These proactive steps should be taken to avoid contamination, the working group report says:

Prevention requires all staff to communicate and be aware, the report says.

Contamination Detection

There are currently no visual ways or chemical field methods to detect whether contamination has taken place, the report says. The working group notes that industry is working to find solutions to this significant challenge and recommends reconciliation of fluid transfer logs and usage figures in the meantime.

Response to Contamination Event

While proactivity and attention to detail can reduce the risk of contamination, the working group highly recommends implementing an emergency response plan to execute when contamination has occurred. This plans would cover responsibilities for FBOs, airports and aircraft operators.

Short- and Long-Term Recommendations for Aircraft Operators and FBOs

More specifically, the working group recommends several ways for various stakeholders to prepare for and confront the risks of DEF contamination. For aircraft operators and FBOs, recommended mitigation techniques include:

Aircraft Operators






These outlined procedures and recommendations “are a good first step but most certainly not the last,” the working group report says. The report also urges “all stakeholders to review this report and use it to review their particular segment of the overall system and to make immediate and appropriate changes.”

The working group includes representatives from the following organizations: Aircraft Owners and Pilots Association, Avfuel, CommScope, Dassault Falcon Jet, Fair Wind Air Charter, National Business Aviation Association, FAA, FBO Partners, Epic Fuels, General Aviation Manufacturers Association, GAMMON Technical Products, Gulfstream, Murray Equipment Inc., Midwest Aviation, National Air Transportation Association, Phillips 66, Sheltair, Signature Flight Support, TAC Air, Total Control Systems, Truckee Tahoe Airport, Union Pacific and World Fuel Services.

To view the report in its entirety, visit:

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