Narrative:

After departure from ZZZ1 center called us up and said several people on the ground at sun witnessed our aircraft venting something from the wing. During the flight I went back and looked out the right and left side windows and saw nothing out of the ordinary. Upon returning to the cockpit my first officer and I discussed what could have happened and came to the conclusion that it was probably some fuel trapped in the naca scoop vent line and vented itself out; or it was the potable water system we had just dumped prior to departure venting some water and there was no further concern and continued on to our first stop at ZZZ2. Upon landing we contacted technical operations at gulfstream. They informed us that this type of event can happen due to trapped fuel in the naca scoop; and no further action is required. We fueled at ZZZ2; loaded our passenger and took off for ZZZ. On departure the tower informed us we were venting something. My decision was to continue the flight based on WX being better at our destination and the shortness of the leg and the amount of fuel on board (enough for two more legs plus reserve). During flight I went back and this time did note vapor coming from under the right wing. We monitored the fuel balance and had no other indication lights or warnings in the cockpit. When we stopped on the ramp at FBO; line service personnel informed us that we had fuel coming out of our right wing. I immediately had the passenger off the aircraft and line service contained the spill with no further problems.callback conversation with reporter revealed the following information: reporter stated that after landing at ZZZ and with the engines secured; the fuel vent continued to have fuel flow from it. The cause was found to be the failure of the fuel vent float mechanism in the outboard surge tank. The surge tank is where fuel supplied to the engine is not burned (excess fuel for cooling) and is dumped back into that tank. The tank is in such a position that after the engines were secured there remained enough fuel in the tank to cause an extensive fuel spill on the ground. Reporter stated that gulfstream maintenance replaced the float valve mechanism prior to the aircraft being airworthy. Additionally; the reporter stated that gulfstream indicated that it was rare for the mechanism to fail.

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Original NASA ASRS Text

Title: GULFSTREAM G200 FLT CREW HAS FUEL VENT FROM R WING DURING TAXI; TKOF AND CRUISE.

Narrative: AFTER DEP FROM ZZZ1 CTR CALLED US UP AND SAID SEVERAL PEOPLE ON THE GND AT SUN WITNESSED OUR ACFT VENTING SOMETHING FROM THE WING. DURING THE FLIGHT I WENT BACK AND LOOKED OUT THE RIGHT AND LEFT SIDE WINDOWS AND SAW NOTHING OUT OF THE ORDINARY. UPON RETURNING TO THE COCKPIT MY FO AND I DISCUSSED WHAT COULD HAVE HAPPENED AND CAME TO THE CONCLUSION THAT IT WAS PROBABLY SOME FUEL TRAPPED IN THE NACA SCOOP VENT LINE AND VENTED ITSELF OUT; OR IT WAS THE POTABLE WATER SYSTEM WE HAD JUST DUMPED PRIOR TO DEP VENTING SOME WATER AND THERE WAS NO FURTHER CONCERN AND CONTINUED ON TO OUR FIRST STOP AT ZZZ2. UPON LNDG WE CONTACTED TECHNICAL OPERATIONS AT GULFSTREAM. THEY INFORMED US THAT THIS TYPE OF EVENT CAN HAPPEN DUE TO TRAPPED FUEL IN THE NACA SCOOP; AND NO FURTHER ACTION IS REQUIRED. WE FUELED AT ZZZ2; LOADED OUR PAX AND TOOK OFF FOR ZZZ. ON DEP THE TWR INFORMED US WE WERE VENTING SOMETHING. MY DECISION WAS TO CONTINUE THE FLT BASED ON WX BEING BETTER AT OUR DEST AND THE SHORTNESS OF THE LEG AND THE AMOUNT OF FUEL ON BOARD (ENOUGH FOR TWO MORE LEGS PLUS RESERVE). DURING FLT I WENT BACK AND THIS TIME DID NOTE VAPOR COMING FROM UNDER THE R WING. WE MONITORED THE FUEL BALANCE AND HAD NO OTHER INDICATION LIGHTS OR WARNINGS IN THE COCKPIT. WHEN WE STOPPED ON THE RAMP AT FBO; LINE SERVICE PERSONNEL INFORMED US THAT WE HAD FUEL COMING OUT OF OUR R WING. I IMMEDIATELY HAD THE PAX OFF THE ACFT AND LINE SERVICE CONTAINED THE SPILL WITH NO FURTHER PROBS.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT AFTER LNDG AT ZZZ AND WITH THE ENGS SECURED; THE FUEL VENT CONTINUED TO HAVE FUEL FLOW FROM IT. THE CAUSE WAS FOUND TO BE THE FAILURE OF THE FUEL VENT FLOAT MECHANISM IN THE OUTBOARD SURGE TANK. THE SURGE TANK IS WHERE FUEL SUPPLIED TO THE ENG IS NOT BURNED (EXCESS FUEL FOR COOLING) AND IS DUMPED BACK INTO THAT TANK. THE TANK IS IN SUCH A POSITION THAT AFTER THE ENGS WERE SECURED THERE REMAINED ENOUGH FUEL IN THE TANK TO CAUSE AN EXTENSIVE FUEL SPILL ON THE GND. RPTR STATED THAT GULFSTREAM MAINT REPLACED THE FLOAT VALVE MECHANISM PRIOR TO THE ACFT BEING AIRWORTHY. ADDITIONALLY; THE RPTR STATED THAT GULFSTREAM INDICATED THAT IT WAS RARE FOR THE MECHANISM TO FAIL.

Data retrieved from NASA's ASRS site as of January 2009 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.