What was found
AIR TURN BACK FOR MULTIPLE LEVEL 1 AND LEVEL 2 FUEL SYSTEM ALERTS. TANK 1 QTY GAUGE WAS INTERMITTENT AND GAVE NUMEROUS AND ERRONEOUS HIGH AND LOW INDICATION WHICH RESULTED IN MULTIPLE ATTEMPTS BY THE FSC TO RE-BALANCE THE FUEL BY TRANSFERRING FUEL BOTH IN AND OUT. WITH THE QTY GAUGE GIVING ERRONEOUS INDICATIONS IT BECAME IMPOSSIBLE TO DETERMINE THE TRUE QTY IN TANK 1. MATH CHECKS TO ESTIMATE FUEL ON BOARD SHOWED, AT TIMES, UP TO 3700 POUNDS OF FUEL UNACCOUNTED FOR SO A LEAK COULD NOT BE POSITIVELY RULED OUT. EMERGENCY DECLARED, NO ASSISTANCE REQUIRED EXCEPT VISUAL INSPECTION BY ARFF UPON LANDING. SHGN 21AUG22 23:15 MEM U PERFORMED GVI OF LH WING REF MD11 AMM 05-21-01-6 AND FOUND NO EVIDENCE OF FUEL LEAKING FROM #1 TANK,, PERFORMED BITE CHECK OF FQBU REF MD11 FIM 28-41-00-1 AND FOUND NUMEROUS FAULTS ON LAST FLIGHT LEG FOR TANK1 TU10,TU11, AND TU12 CAP OUT FAULT. SUSPECT #1 TANK IB MJP. REQUIRES FURTHER TROUBLESHOOTING. ORIG SUB DATE: 9/6/2022