What was found
AFTER TAKEOFF, RECEIVED A LVL 1 FUEL CONTAMINATED ALERT. DURING RETURN TO LANDING ALERT WENT AWAY. INTERROGATED ALL THREE AIU'S. NO FAULTS FOUND. R & R NR 1, 2, AND 3 ENG FUEL FILTERS IAW MM 73-11-02. NO CONTAMINANTS FOUND. RAN NR 1, 2, AND 3 ENGINES IAW JRH. ALL PERAMETERS NORMAL. LEAK CHECKED NORMAL. IAW FIM 73-31-01, B, SYS IS OK. ACFT OK FOR SERVICE.