Date: 201502
Local time of day: 0601-1200
Location: ZZZZ.Airport, FO
Flight conditions: VMC
Light: Night
Aircraft: B767 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
ATC / advisory: Center ZZZZ
Aircraft component: Fuel Quantity-Pressure Indication
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Anomaly: Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Fuel Issue
Detector: Person Flight Crew
When detected: In-flight
Result: General Declared Emergency
Contributing factors: Aircraft; Procedure
Primary problem: Ambiguous

Narrative: On initial briefing the crew noticed a history of problems with the Fuel Qty Channel system resulting in numerous status messages and maintenance actions; including: four just before this flight.  The maintenance action taken for that item has been: Bite Check Fuel Processor No Faults Found. Replaced EICAS Sign Consolidation Card Ref MM31-XX-XX. The crew spoke to Dispatch and Maintenance Control and inquired about the system.  Maintenance Control had no information and could not suggest anything other than to recite the same write-up we had. The crew asked for a copy of the maintenance procedure; and was told to speak to local maintenance. Line maintenance provided a copy of the procedure and the associated wiring diagram; 767 Wiring Diagram Manual; but did not know anything about the repair. Note: There was also a chronic write up involving the Aft Galley FA system constantly chiming. All systems were perfectly normal on preflight and departure. We departed with 98.1 Fuel On Board at the gate. At cruise altitude the flight attendants reported that the FA Galley system again had a repetitive chime which could not be extinguished. After contacting Dispatch and Maintenance Control; the crew performed the Maintenance Control recommended reset maneuver of depowering and repowering buttons on the Forward FA panel. This solved the problem for a short while but had to be repeated throughout the flight; as the incessant chiming reappeared. After several hours of flying; while still in ETOPS airspace; a status message appeared which indicated Fuel Channel Failure.  There were no other immediate malfunctions. The crew compared Totalizer vs. Calculated Fuel on Progress Page 2 of the FMC units; and they indicated approximately 30.5lbs of fuel remaining; between both main tanks.  The center tank was empty.  Within a few minutes; all fuel quantity indications disappeared from the overhead panel; and the Totalizer Fuel number disappeared from Progress Page 2. After reviewing the QRH; and the 767 Flight Manual; and finding no procedure for or reference to a Fuel Quantity Indication failure; the crew contacted Dispatch and Maintenance Control on SATCOM.  Maintenance Control noted the log history but could not provide any help; other than to suggest that the problem might correct itself; 'usually it just comes back'. The crew asked Maintenance Control if there was any other method to determine the quantity of fuel in the tanks; in order to rule out a fuel leak.  He didn't know and just suggested reading the Fuel Leak Procedure in the Flight Manual.  The crew advised they had read that procedure; referenced it; and asked again if there was any way to monitor the fuel quantity (other than visual external inspection) to verify the absence of a fuel leak.  Maintenance Control did not know of anything and did not seem to understand the question. Dispatch did not have any suggestions either. After reviewing the passenger manifest and determining that there were no deadheading pilots on board; the crew briefed the Purser on the situation.  The First Officer (FO) then went back; made a visual inspection; and saw no sign of fuel leak.  The FO also spoke to the flight attendants in the aft section of the airplane and enlisted the help of one of the FAMs who was seated in a window seat; to monitor the situation and advise if they noticed anything.The Captain reviewed the wiring diagram the relevance of Air/GND Signal 1 and Air/GND Signal 2 in relation to the FUEL QTY INDicators; and specifically the history of the Status message appearing; or disappearing after landing.  There were no indications of an air/ground sensing problem nor any C.B.s popped. Maintenance Control sent an ACARS message wondering if the problem had fixed itself yet. After reviewing the situation internally; the crew decided the  safest course of action was to press on to destination; continuing to monitor; but not to accept any delays; such as holding; due tothe inability to determine fuel on board; and therefore make a proper risk assessment of holding delays. Dispatch advised that they would coordinate with ZZZ control to insure there were no delays into ZZZ. When the crew checked in with [next ATC] control; they advised that they would not be able to accept any delays into ZZZZ. Shortly thereafter; Flight was switched to [another ATC] control.  The controller gave a frequency change to speak to an ATC supervisor.  The ATC supervisor inquired into the exact problem; and the crew advised that all systems were normal; except for the loss of fuel quantity indications. The ATC controller advised that the flight would have to declare a PAN or a Fuel Emergency in order to avoid holding in ZZZZ.  The Captain declared a PAN; and confirmed that we required no additional assistance at that time. Shortly thereafter; Dispatch sent a message advising that he had spoken to ZZZZ; and the only way to avoid holding was to declare an emergency; which he advocated doing. The Captain called Dispatch on the SATCOM and tried to clarify whether a PAN or a Fuel Emergency was required to meet ZZZZ ATC requirements. The Dispatcher wasn't sure; and the Captain confirmed that we want to do whatever ZZZZ ATC wants for their airspace.' Meanwhile; ATC was giving us preferential handling; including two or three 'short cuts' with direct clearances through their airspace.  After waiting over 10 minutes and still not receiving clarification from Dispatch; flight declared [our fuel situation with ATC]; but confirmed that they needed no assistance other than an absence of delays. The Captain and flying First Officer brought the resting FO back to the cockpit early to involve him in the situation.   The crew briefed and prepared early for the ILS XXL approach into ZZZZ. There was some discussion of reference speeds; and the veracity of the information on the FMC. All crewmembers compared the landing speeds  references on the FMC against the expected values based on takeoff weight; known fuel on board at takeoff; less burn; and came up with values consistent with the FMC reference page. We had an uneventful approach; landing; and taxi to the gate.  At the gate with the parking brake set; and the parking checklist complete; the fuel quantity indications still were inoperative. While waiting for the jetway driver to appear; the fuel quantity indications reappeared and indicated approximately 20.1 pounds on board; and the FUEL QTY CHANNEL status message disappeared. The crew had previously requested that the fuel tanks be dripped in order to obtain accurate remaining fuel quantity indications for maintenance and the next crew.   Hopefully; this will be helpful to maintenance in evaluating the problem.




Synopsis: B767 Captain reports being dispatched in an aircraft that has had numerous previous write up concerning the fuel quantity indication system. It works initially then fails enroute. Flight continues to destination.