Narrative:

While preparing the aircraft, LR35A, for departure at bfi, I switched the xflow to open and started the right fuel pump for xfer about 200 pounds of fuel to the left wing to balance the fuel load. While the fuel was xferring, I obtained our outbound IFR clearance to ict and proceeded to program the flight plan into the FMS. I then went into the FBO facility at bfi to use the restroom and greet my passenger. When I looked out at the aircraft about 7 mins later, there was fuel venting out of the left tip tank. Immediately, I realized what I'd done and went straight to the aircraft and switched off the right pump and turned the left pump on. The venting fuel stopped and I remained with the aircraft until the fuel system was balanced. The total fuel spilled onto the fuel ramp totaled about 3-4 gals. The left tip tank had become full and as the pump continued to run was venting fuel over-board. Some points about the fuel system are that there is no visual or audio reminder that fuel xfer operations are underway. When I got busy with other preparations, I forgot that I was xferring fuel. The only way to know that fuel is moving is to check the switches and monitor the fuel gauges continuously. By forgetting that fuel was xferring, I created an imbal in the fuel load and spilled about 3-4 gals. These problems were easily corrected and created no problem or delay in our departure. I then learned that when making adjustments to the lear 35 fuel system, it demands continuous attention. I will do my best to never let this occur again. As a captain, I'll also warn others of this danger. In my 4 yrs as a captain on the lear, this is my first mistake with the fuel system and I do not intend to repeat this again.

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Original NASA ASRS Text

Title: PLT OF LJ35 VENTED FUEL ONTO RAMP AT BFI WHEN HE GOT DISTR FROM THE FUEL XFER PROC HE INITIATED TO CORRECT AN OUT OF BAL CONDITION.

Narrative: WHILE PREPARING THE ACFT, LR35A, FOR DEP AT BFI, I SWITCHED THE XFLOW TO OPEN AND STARTED THE R FUEL PUMP FOR XFER ABOUT 200 LBS OF FUEL TO THE L WING TO BAL THE FUEL LOAD. WHILE THE FUEL WAS XFERRING, I OBTAINED OUR OUTBOUND IFR CLRNC TO ICT AND PROCEEDED TO PROGRAM THE FLT PLAN INTO THE FMS. I THEN WENT INTO THE FBO FACILITY AT BFI TO USE THE RESTROOM AND GREET MY PAX. WHEN I LOOKED OUT AT THE ACFT ABOUT 7 MINS LATER, THERE WAS FUEL VENTING OUT OF THE L TIP TANK. IMMEDIATELY, I REALIZED WHAT I'D DONE AND WENT STRAIGHT TO THE ACFT AND SWITCHED OFF THE R PUMP AND TURNED THE L PUMP ON. THE VENTING FUEL STOPPED AND I REMAINED WITH THE ACFT UNTIL THE FUEL SYS WAS BALANCED. THE TOTAL FUEL SPILLED ONTO THE FUEL RAMP TOTALED ABOUT 3-4 GALS. THE L TIP TANK HAD BECOME FULL AND AS THE PUMP CONTINUED TO RUN WAS VENTING FUEL OVER-BOARD. SOME POINTS ABOUT THE FUEL SYS ARE THAT THERE IS NO VISUAL OR AUDIO REMINDER THAT FUEL XFER OPS ARE UNDERWAY. WHEN I GOT BUSY WITH OTHER PREPARATIONS, I FORGOT THAT I WAS XFERRING FUEL. THE ONLY WAY TO KNOW THAT FUEL IS MOVING IS TO CHK THE SWITCHES AND MONITOR THE FUEL GAUGES CONTINUOUSLY. BY FORGETTING THAT FUEL WAS XFERRING, I CREATED AN IMBAL IN THE FUEL LOAD AND SPILLED ABOUT 3-4 GALS. THESE PROBS WERE EASILY CORRECTED AND CREATED NO PROB OR DELAY IN OUR DEP. I THEN LEARNED THAT WHEN MAKING ADJUSTMENTS TO THE LEAR 35 FUEL SYS, IT DEMANDS CONTINUOUS ATTN. I WILL DO MY BEST TO NEVER LET THIS OCCUR AGAIN. AS A CAPT, I'LL ALSO WARN OTHERS OF THIS DANGER. IN MY 4 YRS AS A CAPT ON THE LEAR, THIS IS MY FIRST MISTAKE WITH THE FUEL SYS AND I DO NOT INTEND TO REPEAT THIS AGAIN.

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.