Narrative:

We were taxiing out in ZZZ and had an extended delay on the ground due to thunderstorms in the area. Initially we taxied on only the number one engine. After about 20 minutes; we started the second engine. About 20 minutes later after getting a second reroute from ATC; the number 2 engine was shut down. Shortly thereafter the advisory system activated the fuel system display on the lower ECAM (electronic centralized aircraft monitor) page for a fuel imbalance. The center tank and left main tanks were full; and the right main tank indicated about 7900 pounds. I expected a lower fuel value in the left tank since we had run the APU and number one engine for an extended time; so this did not make any sense. We were in the middle of reprogramming the FMGC (flight management guidance computer) when the ECAM for fuel auto fuel feed fault appeared. As we were doing the ECAM; the aircraft behind us reported fuel leaking from the left wing. ATC called the fire equipment; and within three minutes they were surrounding the airplane. We started the APU (auxiliary power unit); and once it was online; the number one engine was shut down. I called the flight attendants and told them the fire trucks were on their way; and we are not evacuating. I then made an announcement to the passengers. Once the fuel pumps were turned off; the fuel leak stopped. After discussions with operations and the emergency personnel; we decided to tow the airplane to the gate. Once at the gate; the passengers were deplaned via the jet bridge. After some calculations and talking to ZZZ maintenance; we determined that right main tank leaked into the center tank. Once the center tank was full; fuel got rerouted to the left main tank. Once that was full; fuel poured out the left wing ventilation system. We estimated that we lost about 1800 pounds of fuel on the taxiway.

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Original NASA ASRS Text

Title: Flight Crew taxiing A320 encountered fuel spill from wing vent system.

Narrative: We were taxiing out in ZZZ and had an extended delay on the ground due to thunderstorms in the area. Initially we taxied on only the number one engine. After about 20 minutes; we started the second engine. About 20 minutes later after getting a second reroute from ATC; the number 2 engine was shut down. Shortly thereafter the advisory system activated the fuel system display on the lower ECAM (Electronic Centralized Aircraft Monitor) page for a fuel imbalance. The center tank and left main tanks were full; and the right main tank indicated about 7900 pounds. I expected a lower fuel value in the left tank since we had run the APU and number one engine for an extended time; so this did not make any sense. We were in the middle of reprogramming the FMGC (Flight Management Guidance Computer) when the ECAM for Fuel Auto Fuel Feed Fault appeared. As we were doing the ECAM; the aircraft behind us reported fuel leaking from the left wing. ATC called the fire equipment; and within three minutes they were surrounding the airplane. We started the APU (Auxiliary Power Unit); and once it was online; the number one engine was shut down. I called the flight attendants and told them the fire trucks were on their way; and we are not evacuating. I then made an announcement to the passengers. Once the fuel pumps were turned off; the fuel leak stopped. After discussions with operations and the emergency personnel; we decided to tow the airplane to the gate. Once at the gate; the passengers were deplaned via the jet bridge. After some calculations and talking to ZZZ Maintenance; we determined that right main tank leaked into the center tank. Once the center tank was full; fuel got rerouted to the left main tank. Once that was full; fuel poured out the left wing ventilation system. We estimated that we lost about 1800 pounds of fuel on the taxiway.

Data retrieved from NASA's ASRS site 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.