What was found
FUEL IMBALANCE 3 TIMES DURING CRUISE. NO EVIDENCE OF FUEL LEAK. CAPTAIN REPORTED TOTAL FUEL AS EXPECTED & LT & RT FF & F BURN EQUAL. FLIGHT CHARACTERISTICS NORMAL. ACCOMPLISHED CROSSFEED VLV TEST IAW AMM 28-22-00 522-525 NO LEAKAGE ACROSS VLV PASS. VLV OPENS & CLOSES, XFERS FUEL AS COMMANDED. ACCOMPLISHED AMM PRESS REFUEL SYS TEST, DUE SUSPECT POSSIBLE REFUEL VLV LEAK, IAW AMM 28-21-00 501. NO LEAKAGE, TEST OK. CANNOT DUPLICATE FAULT ON GND.