B777-200
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Flight Crew Landed As Precaution; Flight Crew Returned To Departure Airport; General Declared Emergency; General Maintenance Action
Aircraft
While on rest break; the other Relief Pilot and I were called up to the cockpit by the Captain following 'blanking' of the left main fuel tank quantity indicator. After consultation with checklists; Dispatch; Maintenance Control; MEL (for reference only); and applicable landing data; the Captain elected to return to departure airport; declare an in flight emergency and land overweight.
Departed for overseas [on schedule] and approximately one hour into flight; while on my scheduled break; I was notified by a Flight Attendant to return to the cockpit at the Captain's request. The Captain briefed the other Relief Pilot and me that the left main fuel quality indicator quit displaying. He and the First Officer consulted the QRH and found no procedure for this. We also consulted the QRH and concurred with this. The Captain then contacted Dispatch and had a conference call with Maintenance Control. It was decided by all involved that we did not meet the MEL requirements; did not meet the fuel requirements; and could not meet the ETOPS requirements as dispatched for this flight to continue overseas. The decision was made to return. The Captain briefed the flight attendants that they did not have to brief for an emergency landing; and advised the passengers of the situation and our intentions. The Captain discussed with Dispatch the decision to dump fuel or land overweight. As the fuel quantity was unknown; the Captain decided the safest course of action would be to land overweight. There were no other system problems that were affecting the performance of the aircraft. An emergency was declared because of the overweight landing. All performance charts were reviewed; aircraft landed with a minimum rate of descent landing. CFR imaged the brakes for excessive heat; with none noted and then the Captain taxied the aircraft to the gate.
B777 Relief Pilots are informed one hour into flight by the operating crew that they have lost fuel quantity indication in the left main tank and are returning to the departure airport. An uneventful overweight landing ensues.