Date: 201901
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Parked
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Confusion; Training / Qualification; Communication Breakdown
Second reporter function: Technician
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural FAR; Inflight Event / Encounter Fuel Issue
Detector: Person Maintenance
When detected: Aircraft In Service At Gate
Result: Flight Crew Overcame Equipment Problem
Contributing factors: Aircraft; Human Factors; Manuals; Procedure; MEL
Primary problem: Human Factors

Narrative: Upon arrival at aircraft found two open write-ups in logbook. One for loose taxi light and other for essentially higher than normal indication of fuel burn between main tanks. I don't remember the exact wording. This also matched a similar write-up from the previous flight that mx (Maintenance) signed off by saying it was IAW (In Accordance With) with normal limits. Somewhere during pre-flight we noticed no indication on right main fuel tank. The fuel gauges all indicated normal when we first boarded and we had release fuel. We had already informed operations that we needed a mechanic to address the open write-ups and I assumed that the right tank indication was related to the previous write-ups; but they would all be addressed by mx action. The mechanic retrieved the logbook and went to work. Thinking that the MEL (Minimum Equipment List) was simple and would not preclude flight; I allowed boarding to continue. During the delay I found almost no communication with operations was possible so I repeatedly got off the aircraft to get agents to bring out food as we were not catered; delay kits and to get aircraft water service as we had not been not overnight. Several passengers wanted to be removed and all appropriate PAs made. I was also in regular contact with Dispatch and Maintenance Control. I needed to get off aircraft to check on the mechanic and ZZZ Operations multiple times during the three-hour delay; as I was getting no updates. After three hours the mechanic said he needed to collar some circuit breakers and that the logbook was finally signed off and coordinated with [Maintenance Control]. I again checked with Dispatch and received an updated release referencing the MELs. I knew I had been originally dispatched with a lot of extra fuel for the flight and I knew from seeing the gauges before the failure that I had been fueled to release. I requested the required fuel slip and had the fueler top off the aircraft and verify again that I had release fuel. The First Officer and I went through the MEL and concurred that all our actions were correct. Finally; with the mechanics assurance that all required actions were complied with; we took off. I printed and closely tracked the fuel log. I checked fuel used at each fix and subtracted fuel used to obtain fuel remaining. The flight was uneventful. Today I was contacted to file this ASAP. In retrospect I should have questioned the mechanics actions in disabling the other tank indications. This left me no cockpit indication of fuel remaining in the cockpit. When I saw Maintenance add MEL 28-09; that no totalizer indication was required; I assumed that it was all related to 28-06. He told me the procedure had him collar multiple CBs (Circuit Breakers) to comply. MEL 28-06 states that the aircraft has two main tank indications and that only one is required. It also states that the center fuel indication is required. I mistakenly assumed that since I had those conditions before the maintenance action; I would be good after maintenance sign off. I also assumed the FMC (Flight Management Computer) could get valid fuel indications from other than the DU (Display Unit) indications and that was maybe why this procedure was valid. I also discussed the original imbalance write-up with [Maintenance Control] and he indicated it was related to new [Company] procedure of not properly maintained the sensors. Since I know how much fuel I have to start with; and I know how much fuel I am burning and have burned; I know how much fuel I have. All boost bumps and fuel low level lights were operating. Throughout this event I was in close contact with Dispatch and [Maintenance Control]. I had no reason to believe the contract mechanic did not do exactly what was in the AMM (Aircraft Maintenance Manual) in coordination with [Maintenance Control]. In retrospect; I should have questioned why after sign off; I did not have my left and center tank indications restored. I mistakenly assumed that this wasthe desired condition after the procedure. What cannot be accounted for is a total fuel leak in both tanks. I assumed this possibility was weighed by the MEL procedure and the procedure was done correctly. I will add as a factor the three hours it took for action; but there was no pushing to depart from anyone. Just frustration.


Second narrative: I was called out to gate to Aircraft X for no power on wing refueling panel. After inspecting the wing fueling panel I went to the cockpit and was told by the outbound flight crew that there was no cockpit indication of the fuel quantity or totalizer. The flight crew questioned the deferrals to the right fuel quantity indication in the logbook performed by ZZZ contract maintenance. After further review I noticed that 4 ea. fuel quantity circuit breakers pulled and collared behind the first officers seat. After reading all the MEL (Minimum Equipment List) references that were applied nothing called for circuit breakers to be pulled per the MEL. I found that MEL 28-6 requires to install a busing plug jumper harness per M/M [number]. The task requires 4 circuit breakers to be pulled and reinstated after the harness is installed. ZZZ contract maintenance did not reinstate the breakers and the flight crew flew the aircraft from ZZZ to ZZZ1 with no fuel quantity indication.


Synopsis: Flight Crew and Maintenance Technician reported fuel quantity indication problem led to incorrect accomplishment of the Minimum Equipment List Procedure.