Date: 201908
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: Marginal
Weather elements / visibility: Rain
Light: Dusk
Aircraft: Twin Bonanza 50
Operator: Personal
Operating under: Part 91
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Reporter organization: Personal
Reporter function: Pilot Flying; Single Pilot
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Engineer; Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Multiengine
Human factors: Training / Qualification; Confusion
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown
Detector: Person Flight Crew
When detected: Aircraft In Service At Gate
Result: General Maintenance Action
Contributing factors: Airport; Staffing; Human Factors
Primary problem: Staffing

Narrative: Wrong fuel - JET-A; was added to my aircraft. This aircraft is equipped with AvGas ONLY 100LL placards and stenciled marking AvGas ONLY 100LL. The aircraft taxied into Transient Aircraft parking area. I requested 'Top off main tanks only.' I then became busy/distracted with securing aircraft for heavy weather/thunderstorms. When I finished the installation of the control locks and rudder pedal locks I exited the aircraft. It was at that time I noticed the departing fuel truck was labeled with the black placard JET-A. I then stopped the driver and he told me he had just added 29 gallons of JET-A to my aircraft; a Twin Bonanza. This aircraft is clearly an old vintage aircraft and does not resemble in any fashion a turbine powered engine cowling or exhaust system. It then became apparent to me that the driver/fueler was obviously new to this position. However I could not understand how he could have inserted the 'JET-A DUCKBILL style' refueling nozzle into my Avgas tanks. When I examined the refueling nozzle there was no 'Duckbill.' In place of the 'Duckbill' was a conventional round AvGas nozzle. I asked why the 'Duckbill' was not in place and I received a puzzled look as if the fueler was unaware of the difference between the different designs. Further discussions with him revealed he was unaware of the deadly consequences of this error. His immediate Supervisor; who had been there during part of this re-fueling operation understood the entire mess we were now involved in. He suggested they would drain and refill the tanks for me. I told him that only an A&P would be doing any work on the aircraft and that he needed to contact his boss. The fuel tanks were drained and flushed by the local A&P. However prior to next engine start; further research and discussions with my A&P/IA were conducted. Those discussions revealed that the electric fuel pump as an area/volume of space around it that would hold the jet fuel even though the tank was drained of fuel. Because Jet-A is heavier than AvGas it would have settled into that void and when the electric pump was turned ON the Jet-A would then be pumped into the fuel system. This small but significant amount of Jet-A would be delivered to the engines. I then disconnected the fuel supply lines at the firewall and drained the fuel lines and cross-feed system prior to next flight.The night Supervisor was concerned from a 'customer relations perspective' but did not seem to be aware or understand how little Jet-A fuel it takes to damage a piston engine. As the fuel was being drained he told me there should be no worries that you couldn't see; smell or feel any of the Jet-A fuel and so therefore I should not be worried. The next day I gave him a copy of an accident report for a Navajo that had 30 gallons of Jet-A added and the subsequent accident killed all on board. He acted as if I was annoying him with this. When I told him I was going to drain/flush the fuel lines he reluctantly acquiesced to this demand. He muttered something to the effect of 'This is way too much overkill; the fuel is drained already.' Six days later a passenger on my flight went by the airport and inspected the Jet-A trucks. Both had the 'round avgas fuel nozzles; no duckbills in sight.' I am puzzled and perplexed that even after showing the FBO manager the consequences of refueling errors they would still keep the round fuel nozzles in place. Regulatory requirement that 'duckbill style' Jet-A nozzles be in place unless the refueling operation requires a round style nozzle. In that case the 'duckbill' be replaced as soon as refuel is complete. Aircraft mis-fueling events must be reported to NTSB or FAA database to help track errors and develop solutions. Pilot stays completely engaged with fueling operations. Complete readily available guidance from aircraft manufactures regarding the management of refueling errors. I would have never considered the effects Jet-A fuel settling into the electric fuel pump sump area.




Synopsis: Twin Bonanza pilot reported that FBO fueler serviced aircraft with Jet-A instead of AvGas.