What was found
AIR INTERRUPT, RETURNED, EMER DECLARED & LANDING UNEVENTFUL. DURING CLIMB OUT AFTER CTR FUEL TANK WAS EMPTY, CREW NOTICED A FUEL IMBALANCE WITH LT MAIN TANK 8.5 & RT MAIN 7.1. ACCOMPLISHED FUEL TRANSFER BETWEEN TANKS, CHECKED NORMAL, NO EVIDENCE OF FUEL MIGRATION NOTED. ACCOMPLISHED FUEL STICK READINGS & FUEL QTY CHECKS NORMAL IAW FUELING MANUAL MM 28-22-00, NO PRIOR HISTORY.