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NBAA, Industry Examine Fuel Contamination Hazards Following Second DEF Incident

Aug. 30, 2018

NBAA is disturbed by a second business aviation jet fuel contamination incident in nine months. The most recent event could have led to a serious accident were it not for the prompt actions of the flight crew.

On Aug. 14, a Dassault Falcon 900EX, operated by Fair Wind Air Charter, was forced to return to Miami-Opa Locka Executive Airport (OPF) after the flight crew received multiple clogged fuel filter warnings on departure, followed by failure of the trijet's number 2 engine. The aircraft returned safely to OPF, but not before a second engine became unresponsive to throttle inputs.

Subsequent testing revealed fuel contamination consistent with the presence of diesel exhaust fluid, or DEF. Federal mandates require the urea-based solution be used to lower noxious emissions from diesel-powered ground vehicles operated on public roads. When mixed with Jet-A, the solution forms non-soluble crystals that can clog aircraft fuel systems.

NBAA President and CEO Ed Bolen noted a similar fuel contamination event occurred last November at Eppley Airfield (OMA) in Nebraska, triggering a special airworthiness information bulletin from the FAA cautioning operators about DEF contamination.

“Despite that advisory, this latest incident demonstrates that while rare, these incidents do occur, and highlights the need to closely examine methods to mitigate and eliminate this potential hazard,” Bolen said.

Several aircraft may have received contaminated fuel at OPF before the problem was revealed, according to Fair Wind Chief Operating Officer Alex Beringer. The FBO traced the issue back to a fuel system icing inhibitor additive (FSII, also known as Prist) tank that had been removed from a fuel truck for repair, then accidentally filled with DEF for leak checks prior to reinstallation. The fluids are similar in appearance.

"The FBO had procedures in place to avoid cross-contamination, including the fuel farm DEF hose being too short to reach the Prist tank," Beringer explained. "However, those procedures were contingent on the tank not leaving the truck." The FBO has since relocated the DEF tank away from the farm, he added.

NBAA Safety Committee Vice-Chairman Tom Huff noted the committee, in collaboration with other NBAA groups and concerned industry stakeholders, will coordinate a thorough hazard assessment of the issue.

“That will include leveraging subject matter experts and industry partners to identify hazard causes and develop targeted mitigations as well as outreach to FBOs and fuel providers to review their fuel and additive handling practices,” Huff said.

In an Aug. 27 release, Fair Winds also called upon regulatory officials and industry groups, including NBAA, to take further action on the matter of fuel contamination, including a possible exemption from the DEF mandate for airport ground equipment. “Even the best mitigation strategies are still subject to human error,” Beringer added. Read the Fair Winds statement.