Date: 201809
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: B737 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Parked
Aircraft component: Fuel Storage System
Component problem: Improperly Operated
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Human factors: Communication Breakdown; Situational Awareness
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown
Detector: Person Flight Crew
When detected: Routine Inspection
Result: General None Reported / Taken
Contributing factors: Company Policy; Environment - Non Weather Related; Human Factors; Procedure
Primary problem: Ambiguous

Narrative: I; as the pic of this flight; was informed that fuel was removed (defueled) from another aircraft; and boarded on Aircraft X; the aircraft assigned to me for the planned flight. A total of 1794 gallons. As evidenced by [the two] fuel receipts (1777 gals) and (17 gals). On both receipts was written 'defuel payback.' Statements from the mechanic that brought the fuel receipts to the cockpit; along with the actual receipts as mentioned above. Clearly stating 'defuel payback' and that the fuel boarded was defueled from another aircraft. At this point; I have not been able to determine who authorized or ordered this. I contend that the mechanic fueling the airplane knows better ; and the fuel truck operator knows; that fuel removed from (defueled) another aircraft; is considered contaminated; and should not; must not; be boarded on another airplane. That's why a separate; specific; 'defuel truck' is normally used for this defueling process I contacted [Operations Control]; and [Maintenance Control]; and advised of the situation. Which prompted the reciprocal emails from the chief pilot.[The following is a copy of the email the reporter sent to the Chief Pilot]As per our conversation; I advised that from my experience as a professional Flight Engineer; Flight Mechanic; and now PIC of this flight; with 35 years of experience in the business; whenever an airplane is de-fueled; that fuel is considered contaminated; and should NOT be boarded on another airplane.Now; having stated the above; I understand that I have been ordered to complete this flight; and request a 'white bucket test' of the fuel on the aircraft. I have entered this item in the aircraft log to be certified by maintenance; that a fuel contamination check of all tanks was completed; and that this aircraft is safe to conduct the flight as planned.Please be advised that I intend to file a [safety] report; and will attach this correspondence.[Signed as an email. Below is the response reporter received from the Chief Pilot][Pilot] per our conversation in conjunction with guidance of the [Chief Pilot and other advisors] you are legal to use defueled fuel from our company aircraft under the same fueling program. If you would like to request a white bucket test please feel free to do so as you are responsible if you feel there is doubt of fuel contamination. There are no requirements in [the manual] that prevent utilizing fuel defueled from company aircraft and being used in other company aircraft. [Signed as an email. Reporter narrative continues.]As stated in my email; in my 35 years working in maintenance; or flight operations; (I am still researching the FAR prohibiting this action) but; it has been my experience this is illegal; or at least; does not meet the 'best practices standard' with regard to safety. For instance; was the defuel truck maintained to the same safety standards with regards to the filters; draining schedule; and other requirements as a live refueling truck.The maintenance person fueling the airplane should have known better; the fuel truck operator should have known better; but no one did anything to prevent this from happening. I question the training and experience of both. I arrived at the airplane at my normal showtime; and had this been brought to my attention before this event; I; as the pic; would not have allowed this to happen.




Synopsis: B737 Captain reported that fuel that was defueled from another aircraft was used to fuel the assigned aircraft.