Narrative:

I gave instructions to line crew to top both tanks with the intention of departing at approximately xx:00Z. At about WX:30Z I went out to preflight the plane, warm up the engine, and check and drain fuel and check oil ATC. I came back in the office filed an IFR plan for 38D returned to the plane and departed. I climbed out and tower had just switched me over to departure when I noticed a small amount of gasoline entering the airstream above the right gas filler cap. I switched to tower and asked to come back in due to the small leak. I did not declare an emergency. I landed and taxiied back to FBO. When I arrived, there were three fire trucks there which were called by the tower. An FAA representative and fire representative were there and I called a supervisor from FBO over to explain the cause which was a result of the refueling person not placing the chain and safety pin type device inside the fuel tank carefully. I opened the cap and showed everyone there that it is possible to open the cap, check fuel, and close cap west/O noticing that the safety pin device was laying in the O ring groove. When the safety pin device (which secures the chain to the tab below the O ring groove) lays in the O ring groove, it is possible to close the cap securely but the pin will distort the O ring just enough to allow gasoline to escape in the airstream created by high speed. FBO retopped the tank. I calculate I lost approximately 1 1/2 gal of fuel due to this problem. I would recommend a much larger circular attaching device similar to a 1 1/2'' key ring to attach the ball chain to the tank this way it would be impossible to close and secure the cap if the ring or chain got into the O ring groove. The FAA representative asked me a few questions and said I would not be cited.

Related reports:

Google
 

Original NASA ASRS Text

Title: PLT OF SMA HAD FUEL LEAK AFTER TKOF. RETURNED LANDED. SECURED GAS CAP.

Narrative: I GAVE INSTRUCTIONS TO LINE CREW TO TOP BOTH TANKS WITH THE INTENTION OF DEPARTING AT APPROX XX:00Z. AT ABOUT WX:30Z I WENT OUT TO PREFLT THE PLANE, WARM UP THE ENG, AND CHK AND DRAIN FUEL AND CHK OIL ATC. I CAME BACK IN THE OFFICE FILED AN IFR PLAN FOR 38D RETURNED TO THE PLANE AND DEPARTED. I CLBED OUT AND TWR HAD JUST SWITCHED ME OVER TO DEP WHEN I NOTICED A SMALL AMOUNT OF GASOLINE ENTERING THE AIRSTREAM ABOVE THE R GAS FILLER CAP. I SWITCHED TO TWR AND ASKED TO COME BACK IN DUE TO THE SMALL LEAK. I DID NOT DECLARE AN EMER. I LANDED AND TAXIIED BACK TO FBO. WHEN I ARRIVED, THERE WERE THREE FIRE TRUCKS THERE WHICH WERE CALLED BY THE TWR. AN FAA REPRESENTATIVE AND FIRE REPRESENTATIVE WERE THERE AND I CALLED A SUPVR FROM FBO OVER TO EXPLAIN THE CAUSE WHICH WAS A RESULT OF THE REFUELING PERSON NOT PLACING THE CHAIN AND SAFETY PIN TYPE DEVICE INSIDE THE FUEL TANK CAREFULLY. I OPENED THE CAP AND SHOWED EVERYONE THERE THAT IT IS POSSIBLE TO OPEN THE CAP, CHK FUEL, AND CLOSE CAP W/O NOTICING THAT THE SAFETY PIN DEVICE WAS LAYING IN THE O RING GROOVE. WHEN THE SAFETY PIN DEVICE (WHICH SECURES THE CHAIN TO THE TAB BELOW THE O RING GROOVE) LAYS IN THE O RING GROOVE, IT IS POSSIBLE TO CLOSE THE CAP SECURELY BUT THE PIN WILL DISTORT THE O RING JUST ENOUGH TO ALLOW GASOLINE TO ESCAPE IN THE AIRSTREAM CREATED BY HIGH SPD. FBO RETOPPED THE TANK. I CALCULATE I LOST APPROX 1 1/2 GAL OF FUEL DUE TO THIS PROB. I WOULD RECOMMEND A MUCH LARGER CIRCULAR ATTACHING DEVICE SIMILAR TO A 1 1/2'' KEY RING TO ATTACH THE BALL CHAIN TO THE TANK THIS WAY IT WOULD BE IMPOSSIBLE TO CLOSE AND SECURE THE CAP IF THE RING OR CHAIN GOT INTO THE O RING GROOVE. THE FAA REPRESENTATIVE ASKED ME A FEW QUESTIONS AND SAID I WOULD NOT BE CITED.

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.