Fuel System Icing Inhibitor (FSII) contamination with Diesel Exhaust Fluid (DEF) is a very serious threat to the safety of flight. There have been at least four known incidents where FSII was mistaken for DEF, leading to inflight emergencies, including both partial and complete engine failures, nine emergency landings, and at least one aircraft deadstick landing – narrowly avoiding a tragic outcome.
These contamination events are 100% preventable with the proper training and procedures in place. NATA urges its members and all refueling operators that utilize FSII and DEF to to adopt OBP-36-Preventing FSII Contamination with DEF and any Other Product.
NATA also offers training on FSII Contamination Prevention through our Safety 1st Training Center.
For questions regarding FSII Contamination with DEF, please contact safety1st@nata.aero.
Safety 1st Alert: Critical Issue – DEF Contamination Event OBP-36-Preventing FSII Contamination with DEF and any Other Product EI Video: Control of FSII and DEF at Airports NATA Safety 1st Alert EI 1538 Handling of Fuel System Icing Inhibitor and Aviation Fuel Containing Fuel System Icing Inhibitor at Airports NTSB Alert Aircraft Diesel Exhaust Fluid Contamination Working Group Report & Recommendations Safety Risk Management DEF Report - August 30, 2019 DEFKit - DEF in FSII Test Kit SAFO18015 Jet Fuel Contaminated with Diesel Exhaust Fluid (DEF) FAA SAIB Engine Fuel and Control – Operation with Contaminated Jet Fuel FAA April SAIB Engine Fuel and Control – Operation with Contaminated Jet Fuel