Air Ambulance By Air Trek Cessna 550 incident
Cessna 550 · Incident: fuel contamination en route
From Naples Municipal Airport (APF) to Niagara Falls International Airport (IAG)
Event
- NTSB case
- ERA19IA178
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Incident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- Charter & commuter
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Cessna 550
- Aircraft type
- Cessna 550
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N744AT
- Operator
- Air Ambulance By Air Trek
- Onboard fatalities
- Unknown
- Route
- From Naples Municipal Airport (APF), Naples, FLTo Niagara Falls International Airport (IAG), Niagara Falls, NY
- Aircraft age
- About 36 years (built 1983)
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 135: Air Taxi & Commuter
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- En route · cruise
- Defining eventThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Fuel contamination
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- None
Cause areas
- Aircraft › Fluids/miscellaneous hardware
- Environmental issues › Physical environment
- Personnel issues › Action/decision
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The crew of the air medical flight reported that, while in cruise flight at 35,000 ft mean sea level, the left engine began losing power. The crew requested a lower altitude from air traffic control, shut down and secured the left engine, and diverted. While descending, the right engine lost all power, and the crew performed an uneventful forced landing to the diversion airport.
Several days after the incident, the lineman who worked at the fixed-base operator (FBO) where the airplane was most recently fueled realized that he had inadvertently combined the contents of an unmarked, partially empty container of fuel system icing inhibitor (FSII) with a partially-empty container of diesel exhaust fluid (DEF), assuming that both containers contained FSII. The container of DEF was co-located with the container of FSII, which was contrary to the FBO's policy of isolating DEF off-airfield. The lineman then serviced the fuel truck FSII reservoir with the DEF/FSII combination. The following day, the incident airplane was fueled with Jet A fuel from the truck, and FSII additive from the truck was mixed at the time of fueling. Postincident testing revealed the presence of urea, one of the primary components of DEF, in the incident airplane's fuel system samples.
When combined with hydrocarbon jet fuels, urea forms a solid precipitate, or clathrate, that is known to interfere with fuel filtering and fuel system operation. The presence of DEF in the incident airplane's fuel system resulted in a blockage, which led to the total loss of engine power.
Probable cause
The lineman's inadvertent introduction of diesel exhaust fluid (DEF) to the fuel truck fuel system icing inhibitor reservoir, which resulted in fuel contamination and a total loss of engine power. Contributing to the accident was the fixed-base operator's failure to ensure that DEF was stored off-airfield in accordance with their own policy.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ERA19IA178
- Event ID
- 20190514X85601
- Case number
- ERA19IA178
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status, coordinates, damage. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 1ee6458edbab6168257d2c051b13f593c57a576201f0b2884595fccdf6f97489; retrieved 2026-09-16T09:00:10.708Z.