What was found
(CAN) ACFT SITTING IN HANGAR. CAME IN TO FIND LARGE PUDDLE OF FUEL ON FLOOR. FOUND RUBBER CAP COVERING LOWER FWD PORTION OF FUEL TANK CRACKED AND DRIPPING FUEL. FUEL TANK HOLDS 940 LBS OF FUEL AND RUBBER CAP COVERS A 1" DIAMETER OPENING. RUBBER CAP WAS 9.5 YEARS OLD AND IS NORMALLY REPLACED AT 12 YR O/H, BUT SHOULD BE REPLACED BEFORE THAT DUE TO RUBBER DETERIORATION IN CONTACT WITH AROMATIC FUEL AND STATIC PRESSURE. REPLACEMENT SHOULD PROBABLY SYNC WITH 6 YEAR RUBBER HOSE CHANGE. WOULD NOT LIKE TO SEE THIS HAPPEN IN FLIGHT. CRACKED CAP WAS REPLACED WITH NEW CAP PN 350A77-1231-21 TO RETURN ACFT TO SERVICE. COMPANY MAINTENANCE CAP 6YR REPLACEMENT WILL BE ENTERED INTO ACFT MAINTENANCE TRACKING RECORDS AS PART OF COMPANY OPS RISK ASSESSMENT PROGRAM.