What was found
PDIS 628 28-40 2047 21AUG22 MEM OPEN U 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. FACT 22AUG22 19:46 MEM ITEM WAS REOPENED IN ERROR. SEE PREVIOUS UPDATES FOR WORK ACCOMPLISHED.