Date: 201707
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness
Second reporter function: First Officer; Pilot Flying
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Weight And Balance; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural MEL / CDL; Inflight Event / Encounter Fuel Issue
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Landed in Emergency Condition; Flight Crew Diverted; General Maintenance Action
Contributing factors: Aircraft; Human Factors
Primary problem: Human Factors

Narrative: We departed with a cockpit left main fuel quantity indicator placarded inoperative. Per MEL; we received a fuel slip which indicated a total fuel load of 18;500 pounds. At lift off the airplane was right wing heavy and took about one unit of rudder trim to level the wings in cruise. The left fuel quantity indication decreased reaching zero during cruise at 31;000 feet. Immediately thereafter the left engine started to roll back. We opened the fuel crossfeed valve and the engine recovered and continued to run. Advised ATC and requested immediate turn towards ZZZ. Landing was uneventful. Total fuel at shut down 3500 pounds; all of it in the right main tank. Left main tank had no usable fuel remaining in it; this was determined by sticking the tank. Contract maintenance; in coordination with Maintenance Control; subsequently placarded the wing left main fuel quantity indicator (in addition to cockpit left main fuel quantity) inoperative. After aircraft was refueled and fuel quantity verified by sticking the left main tank we ferried the aircraft to ZZZ1. The fuel aboard noted on the fuel slip was NOT what we had aboard the aircraft. Retrain the fueler in the proper procedure for fueling the aircraft with an inoperative fuel quantity gauge or change the procedure. This is a serious safety issue and this flight could have had a much worse conclusion.

Callback: The reporter confirmed that the Fueler did not dip the tank as required by the MEL; but instead used the wing gauge which was not correct.

Second narrative: The aircraft logbook indicated that the aircraft had problems with the fuel indicating system. The left main wing tank indicator was inoperative. Although; the gauge still indicated a number on its display; the amount of fuel it indicates was considered to be in error. Following refueling; we received a fuel slip indicating the proper amount of fuel and reviewed the MEL to ensure the proper procedures were followed in the cockpit. The aircraft flight release included the citation about the fuel indicator. We believed we had received the proper fuel and were properly set for flight. Enroute; about 1 hour into the flight; the left fuel gauge quantity passed '0' pounds indicated. At that point; the engine continued to operate; indicating that the tank still contained fuel. However; a few minutes later; the engine RPM began to decay and we felt a momentary yaw. Captain; sensing that the engine was indeed being starved for fuel; immediately opened the main tank fuel crossfeed; the engine recovered. Realizing that we were now in a critical fuel situation (about 4500 lbs remaining); we immediately advised Center and requested a diversion. We had just flown past ZZZ; it was closer; and we knew it was VMC at that time. We immediately turned toward ZZZ and performed an uneventful landing. Our landing fuel state was: Center tank - zero fuel; Left wing tank - zero fuel; Right wing tank - 3500 lbs. Our planned fuel at landing should have been approximately 4200 lbs in each wing tank for a total of approximately 8200 lbs. Captain and I believed the fueling process had not been properly conducted; which resulted in the left tank being shorted approximately 6000 lbs from the desired total of 18000 lbs. There was an error made in fueling the aircraft and the quantity was not verified before or after the fueling process. Although we trusted that the procedure was completed properly; it had not been. An aircraft which is known to have fuel indication problems; should have the fuel 'physically' and 'mathematically' verified. Physically verified with the fuel tank 'sticks' as well as mathematically through computation from prefueling state of the aircraft to the final fuel state.


Synopsis: B737 Flight crew reported diverting enroute after being dispatched with a malfunctioning left wing fuel quantity indicator.