NBAA Cautions Operators Following Latest DEF Contamination Incident

Nov. 9, 2020

NBAA was recently advised of an incident involving the probable contamination of aviation jet fuel with diesel exhaust fluid, or DEF. The association reminds operators to remain vigilant against similar incidents in which the urea-based, emissions-reducing solution could be present in Jet-A, leading to potential engine failure.

On Oct. 20, an Embraer Phenom 300 returned to Savannah/Hilton Head International Airport (SAV) shortly after departure in response to crew alerting system warnings of “ENG 1 and ENG 2 Fuel IMP BYP.” The aircraft landed safely, and subsequent testing “indicated the presence of urea in a fuel sample,” according to an FAA official.

Mandated by the EPA to lower noxious emissions from diesel-powered ground vehicles, DEF is similar in appearance to fuel system icing inhibitor (FSII), also known by the product name Prist. When mixed with Jet-A, DEF forms non-soluble crystals that can clog aircraft fuel systems, leading to reduced engine power or – as has occurred at least three times since 2017 – inflight shutdowns of one or more engines.

Mark Larsen, NBAA senior manager of safety and flight operations, noted while the aircraft had taken on fuel at SAV, the FBO in question was able to demonstrate their procedures and protections adhered to the latest industry guidance to avoid DEF contamination. “Additional investigations are now underway to determine where the aircraft may have taken on the suspect fuel,” he said.

Earlier this year, NBAA submitted comments in favor of expanding FAA training requirements on handling DEF beyond ground personnel at Part 139 commercial airports to encompass any airport with projects funded under the Airport Improvement Program or by Passenger Facility Charges.

That followed the association’s participation in joint industry/FAA discussions about DEF contamination and a subsequent agency panel formed to address the matter. Larsen noted that in the time since the joint industry/FAA recommendations were released, a testing kit is now available to confirm the presence of DEF in a fuel truck’s FSII reservoir, which had been utilized by the FBO in Savannah.

NBAA also addressed the issue during its virtual Safety Town Hall last month, which featured aviation journalist Miles O’Brien, Air Trek, Inc. pilots Bruce Monnier and Gerald Downs, King Schools Founders John and Martha King, and Aircraft Owners and Pilots Association Air Safety Institute Senior Vice President Richard McSpadden. Read more about the Safety Town Hall.

“NBAA continues to seek proactive measures to eliminate the potential of DEF contamination in jet fuel,” he continued. “While we’ve made significant strides in educating airport personnel, operators and regulators about these challenges, this latest incident indicates there’s more to be done.”