B777-200
Flight Crew Air Transport Pilot (ATP)
Troubleshooting; Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural MEL / CDL; Inflight Event / Encounter Fuel Issue
Flight Crew Diverted; Flight Crew Landed As Precaution
Aircraft; Chart Or Publication; Procedure; MEL; Human Factors
During climb; we noticed an unusual vibration in the aircraft. This aircraft had a CDL placard on it for the the removal of the right inboard flap fairing. I believed that the possible source of this vibration was this CDL item. During cruise flight we began to notice an increase in our fuel burn compared to the flight plan. After two hours in flight we were down by 1;000 LBS. After four hours we were down by 3;000 LBS; after six hours we were down by 4;000 LBS. We contacted Dispatch and also contacted our Engine Shop Technicians to determine the possible extra fuel burn. Since the fuel burn was going to burn into my required reserve and alternate fuel required for landing at ZZZZ; I decided to divert into ZZZZ1. We landed at ZZZZ1 and refueled and than continued on to ZZZZ.
Flight from ZZZ to ZZZZ. Entire flight fuel burn was well below flight progress numbers and flight plan even though flight plan profile was flown. Due to marginal weather at destination; the Captain decided to land at ZZZZ1 and add more fuel. The fuel used was 6;000 LBS. below the plan at that point. Refueled at ZZZZ1 and continued to ZZZZ with uneventful flight.
A Captain and First Officer report about an unusual vibration during climb on their B777-200 aircraft after a CDL was applied for removal of the right inboard flap fairing. Crew diverted due to excessive fuel burn; which would have affected required fuel reserve and alternate fuel.