What was found
ACFT WILL RETURN TO FIELD DUE TO HEAVY ODOR OF FUEL IN CABIN. DE-BRIEFED CREW UPON LANDING. HAD FUEL ODOR INITIALLY ON GND DURING TAXI BEFORE DEPARTURE. WAS A ONE ENGINE TAXI WITH LT ENG & BLEED SELECTED ON WHEN FUEL ODOR FIRST NOTICED (IAW PROCEDURE BLEED SHOULD HAVE BEEN OFF FOR ONE ENG TAXI). WHEN RT ENG STARTED ODOR SEEMED TO DISSAPATE & TAKE OFF WAS NORMAL. FLT CREW CHECKED WITH CABIN CREW AT FL 100 & INFORMED ODOR WAS GETTING WORSE IN CABIN. UPON ARRIVAL NO OBVIOUS LEAKS OBSERVED, ODOR NOTICABLE IN CABIN WHEN BOARDED CREW ALSO POINTED OUT ODOR SEEMED TO ORIGINATE FROM L2 DOOR. CARGO BAYS AND MIX MANIFOLD AREA CHECKED, NO OBVIOUS ODOR OR LEAKS. FLT CREW CARRIED OUT IDLE PWR EGR FOR T/S PURPOSES OF BOTH ENGINES IN MULTIPLE BLEED CONFIGURATIONS & PACKS CONFIG USING DIFFERENT BLEED SOURCES & COULD NOT REPLICATE ODOR AT IDLE PWR. FURTHER T/S REQUIRED. REF L/P 3680476 FOR CORRECTIVE ACTION OF FUEL LEAK & ODOR. PERFORMED PACK BURN OUT IAW 21-00-01-002-001, NO ODOR PRESENT IN CABIN