A300
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Fuel Issue
Flight Crew Diverted; Flight Crew Landed in Emergency Condition
Aircraft
Passing 18;000 on climbout noticed an unexplained decrease in right outer fuel quantity. Followed QRH procedures for fuel feed manual control and fuel leak. Did not confirm a fuel leak but right outer quantity continued to decrease. Right outer [fuel quantity] should not have burned down at all. After completing fuel feed manual control with center pumps off to ensure fuel was burning from inner tanks right outer continued to decrease. Entered fuel leak checklist and did not confirm a fuel leak because only indication was an imbalance but fuel total continued to burn down on pace with flight plan release. Consulted with [Maintenance] and Airbus tech pilot. Diverted to nearest airport. Aircraft landed exceeding outer wing tank limits; no problems noted. On the ground with engines shutdown and no fuel pumps on; right outer continued to decrease quantity over a one hour period.
[Report narrative contained no additional information.]
A300 flight crew reported an unexplained decrease in right outer fuel quantity and diverted.