What was found
FLAPPER VALVE SEAL PN S-461 FOR LEFT AND RIGHT WING TIP TANKS WERE INSTALLED IAW SB 35/36-28-10 ON 02/19/01 AIRCRAFT HOURS 8,167.3 CUSTOMER ARRIVED AT OUR FACILITY ON 06/04/2001 AIRCRAFT HOURS 8306.9 WITH REPORTED DISCREPANCY AS FOLLOW: INVESTIGATE TIP TANK FLAPPER VALVES BYPASSING FUEL. INVESTIGATION REVEALED LEFT AND RIGHT TIP TANK TO WING FLAPPER VALVES FORWARD AND AFT POSITIONS PN S-461 WERE SWOLLEN AND DEFORMED PERMITTING FUEL FROM WING TO BYPASS INTO THE TIP TANKS.