Date: 201604
Local time of day: 0601-1200
Location: ZZZZ.Airport, FO
Flight conditions: VMC
Light: Daylight
Aircraft: MD-11
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Cargo / Freight / Delivery
Flight phase: Cruise
ATC / advisory: Center ZZZZ
Aircraft component: Fuel System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Relief Pilot
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Anomaly: Aircraft Equipment Problem Critical; Inflight Event / Encounter Fuel Issue
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Diverted; Flight Crew Landed As Precaution; Flight Crew Requested ATC Assistance / Clarification; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: I was on break when asked to come to the flight deck due to a possible fuel leak situation. When I entered the flight deck the captain and the first officer were in the process of running the level 2 suspected fuel leak checklist. I looked at the release and [checklist] to bring myself into the loop to the situation. At the completion of the checklist the captain brought me into the loop prior to contacting dispatch. At that point I began fuel burn check and compared it to our [flight plan]. The captain indicated they had noticed the fuel 600 pounds down; then 1500 pounds; and our next point was indicating more than that. After running my fuel check it indicated we were losing almost 700 pounds in 7 minutes due to either an over burn or fuel leak (calculated burn based on FF at 2300 lbs vs 3000 actual). The trend was we were soon going to have more than 5000 pounds of fuel less than the flight plan planned for; and based on fuel flows should have. The captain was at this time communicating to dispatch; and the FO was communicating with ATC and monitoring the aircraft flight path. At he completion of the call to dispatch; Maintenance; and company it was determined to discontinue the flight and per the checklist 'land at the nearest suitable airport'. We consulted the [checklist]; FOM; and dispatch/company to determine where the 'nearest suitable' airport was. We then contacted ATC and instructed them we were reversing course and heading to [alternate] due to a suspected fuel leak. The captain flew the aircraft; the FO communicated to ATC; and I obtained the weather and diversionary performance numbers. Due to our aircraft gross weight we needed to burn extra fuel to insure we arrived at our landing weight. The captain then requested lower to assist in increasing our fuel burn; and also a place close to [alternate] to hold. We elected not to dump fuel as we were not sure of the location of the suspected leak. Ounce we were satisfied with the aircraft weight; airfield performance numbers; and weather we proceeded to [alternate]. We requested upon landing that CFR visually inspect the aircraft for any signs of fuel being vented prior to taxiing to any ramp. After landing CFR communicated to us via radio there appeared to be no signs of fuel leaking. We then taxied to the designated ramp and shutdown and communicated with dispatch; maintenance; [and] company.




Synopsis: MD-11 Relief Pilot reported the flight diverted after detecting a probable fuel leak.