Narrative:

The aircraft was landed in fsm. As pilot completed delivery of freight for a local operator, fuel was requested by the pilot to the local FBO. The pilot unlatched 2 of the aircraft's 4 fuel caps and waited for the fuel truck. The fuel truck became delayed and the pilot decided to make a fuel stop en route to the destination. A visibility check of the aircraft was made and then the aircraft taxied for departure and took off. Once airborne, fuel was seen trailing down the wings. The aircraft entered a downwind leg and immediately landed. An inspection of the aircraft found that the 2 fuel caps that were unlatched had not been relatched, only pushed down, and came loose during takeoff. They were found on the runway. The caps were not damaged and were latched securely after the aircraft was fueled. The rest of the flight was uneventful. 2 factors contributed to this incident. The first was that while the flight was perfectly legal in a time and duty reference, it did occur during the early morning hours; the pilot was tired. The second factor was that the 2 fuel caps in question cannot be seen from the pilot's seat. The outer caps were always in view, but once the most inward caps were inspected (from a distance, in this case), they cannot be easily seen. An additional factor in this case was that the pilot removed the fuel tanks himself instead of waiting for the lineman to do it--he had never done this before. In summary, a pilot must be rested. While meeting legal requirements, this is not enough. If too tired, do not fly. The fueling process should be done the same way every time. Allow the line person to feel the aircraft and then physically check the caps and sump the tanks yourself. Finally, verify that each tank cap is on during runup for a final check, even if moving around the cockpit (leaning from the seat) is required. Standardized safe procedures make for safe flying.

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Original NASA ASRS Text

Title: FUEL CAPS NOT REPLACED--FUEL OBSERVED LEAKING OUT FILLER CAPS AFTER TKOF. RETURNED LANDED.

Narrative: THE ACFT WAS LANDED IN FSM. AS PLT COMPLETED DELIVERY OF FREIGHT FOR A LCL OPERATOR, FUEL WAS REQUESTED BY THE PLT TO THE LCL FBO. THE PLT UNLATCHED 2 OF THE ACFT'S 4 FUEL CAPS AND WAITED FOR THE FUEL TRUCK. THE FUEL TRUCK BECAME DELAYED AND THE PLT DECIDED TO MAKE A FUEL STOP ENRTE TO THE DEST. A VIS CHK OF THE ACFT WAS MADE AND THEN THE ACFT TAXIED FOR DEP AND TOOK OFF. ONCE AIRBORNE, FUEL WAS SEEN TRAILING DOWN THE WINGS. THE ACFT ENTERED A DOWNWIND LEG AND IMMEDIATELY LANDED. AN INSPECTION OF THE ACFT FOUND THAT THE 2 FUEL CAPS THAT WERE UNLATCHED HAD NOT BEEN RELATCHED, ONLY PUSHED DOWN, AND CAME LOOSE DURING TKOF. THEY WERE FOUND ON THE RWY. THE CAPS WERE NOT DAMAGED AND WERE LATCHED SECURELY AFTER THE ACFT WAS FUELED. THE REST OF THE FLT WAS UNEVENTFUL. 2 FACTORS CONTRIBUTED TO THIS INCIDENT. THE FIRST WAS THAT WHILE THE FLT WAS PERFECTLY LEGAL IN A TIME AND DUTY REF, IT DID OCCUR DURING THE EARLY MORNING HRS; THE PLT WAS TIRED. THE SECOND FACTOR WAS THAT THE 2 FUEL CAPS IN QUESTION CANNOT BE SEEN FROM THE PLT'S SEAT. THE OUTER CAPS WERE ALWAYS IN VIEW, BUT ONCE THE MOST INWARD CAPS WERE INSPECTED (FROM A DISTANCE, IN THIS CASE), THEY CANNOT BE EASILY SEEN. AN ADDITIONAL FACTOR IN THIS CASE WAS THAT THE PLT REMOVED THE FUEL TANKS HIMSELF INSTEAD OF WAITING FOR THE LINEMAN TO DO IT--HE HAD NEVER DONE THIS BEFORE. IN SUMMARY, A PLT MUST BE RESTED. WHILE MEETING LEGAL REQUIREMENTS, THIS IS NOT ENOUGH. IF TOO TIRED, DO NOT FLY. THE FUELING PROCESS SHOULD BE DONE THE SAME WAY EVERY TIME. ALLOW THE LINE PERSON TO FEEL THE ACFT AND THEN PHYSICALLY CHK THE CAPS AND SUMP THE TANKS YOURSELF. FINALLY, VERIFY THAT EACH TANK CAP IS ON DURING RUNUP FOR A FINAL CHK, EVEN IF MOVING AROUND THE COCKPIT (LEANING FROM THE SEAT) IS REQUIRED. STANDARDIZED SAFE PROCS MAKE FOR SAFE FLYING.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.