Narrative:

During taxi out we got an ECAM stating the number 2 pump in the center tank was inoperative. We complied with the ECAM and called maintenance control. Maintenance control elected to defer the pump and we concurred. We complied with the MEL. We took off tank to engine. After takeoff during climb out we opened the crossfeed and turned on the number 1 center tank pump. We had 3500 pounds in the center tank. This was in compliance with the MEL. The number 1 pump did not turn on. After 5 to 10 minutes we decided to go manual on the fuel system to get the number 1 pump to start. It did. We kept this configuration until the center tank was empty. After the center tank was empty; and before shutting off the crossfeed; we noticed that the right wing tank was decreasing; while the left wing main tank was increasing. With everything working right; my understanding was that with all the main inner tank pumps on; even with the crossfeed open we should be burning tank to engine. Instead; all our fuel was coming from the right wing and backfilling the left main tank. By my way of thinking; the left wing pumps were not working (as the center tank pump had also appeared to be working; but it hadn't been wasn't pumping) so I felt to close the crossfeed could possibly risk a flameout. At this point we were developing a significant imbalance. We looked at the fuel imbalance checklist; but decided against it as we did not want to risk a dual flameout. By this time we had a 4000 pound imbalance. We got dispatch and maintenance on the line and explained the situation to them. We all concurred not to change anything at this point because we could not be certain the left wing fuel pumps would work properly. We elected to declare an emergency and divert to ZZZ which was the closest airport. We landed in ZZZ uneventfully; and taxied to the gate. We had over a 7000 pound imbalance at the gate.callback conversation with reporter revealed the following information: the reporter stated that his air carrier grounded this aircraft upon arrival and began an in-depth investigation. One of the first abnormal conditions noted was the underwing fueling panel switches were not in the correct positions. Additionally; the wing tanks were opened to allow for examination of the fueling system components. The pump switches on the inner tanks were changed. The reporter did not have the final maintenance department conclusion about what actually failed.

Google
 

Original NASA ASRS Text

Title: AN A319 RIGHT FUEL TANK PUMPS BACK FILLED THE LEFT MAIN TANK AFTER A CENTER TANK CROSS FEED OPERATION. A SIGNIFICANT FUEL IMBALANCE RESULTED REQUIRING AN EMER DIVERT TO AN ENRTE ARPT.

Narrative: DURING TAXI OUT WE GOT AN ECAM STATING THE NUMBER 2 PUMP IN THE CENTER TANK WAS INOP. WE COMPLIED WITH THE ECAM AND CALLED MAINT CTL. MAINT CTL ELECTED TO DEFER THE PUMP AND WE CONCURRED. WE COMPLIED WITH THE MEL. WE TOOK OFF TANK TO ENGINE. AFTER TAKEOFF DURING CLIMB OUT WE OPENED THE CROSSFEED AND TURNED ON THE NUMBER 1 CENTER TANK PUMP. WE HAD 3500 POUNDS IN THE CENTER TANK. THIS WAS IN COMPLIANCE WITH THE MEL. THE NUMBER 1 PUMP DID NOT TURN ON. AFTER 5 TO 10 MINUTES WE DECIDED TO GO MANUAL ON THE FUEL SYSTEM TO GET THE NUMBER 1 PUMP TO START. IT DID. WE KEPT THIS CONFIGURATION UNTIL THE CENTER TANK WAS EMPTY. AFTER THE CENTER TANK WAS EMPTY; AND BEFORE SHUTTING OFF THE CROSSFEED; WE NOTICED THAT THE RIGHT WING TANK WAS DECREASING; WHILE THE LEFT WING MAIN TANK WAS INCREASING. WITH EVERYTHING WORKING RIGHT; MY UNDERSTANDING WAS THAT WITH ALL THE MAIN INNER TANK PUMPS ON; EVEN WITH THE CROSSFEED OPEN WE SHOULD BE BURNING TANK TO ENGINE. INSTEAD; ALL OUR FUEL WAS COMING FROM THE RIGHT WING AND BACKFILLING THE LEFT MAIN TANK. BY MY WAY OF THINKING; THE LEFT WING PUMPS WERE NOT WORKING (AS THE CENTER TANK PUMP HAD ALSO APPEARED TO BE WORKING; BUT IT HADN'T BEEN WASN'T PUMPING) SO I FELT TO CLOSE THE CROSSFEED COULD POSSIBLY RISK A FLAMEOUT. AT THIS POINT WE WERE DEVELOPING A SIGNIFICANT IMBALANCE. WE LOOKED AT THE FUEL IMBALANCE CHECKLIST; BUT DECIDED AGAINST IT AS WE DID NOT WANT TO RISK A DUAL FLAMEOUT. BY THIS TIME WE HAD A 4000 POUND IMBALANCE. WE GOT DISPATCH AND MAINT ON THE LINE AND EXPLAINED THE SITUATION TO THEM. WE ALL CONCURRED NOT TO CHANGE ANYTHING AT THIS POINT BECAUSE WE COULD NOT BE CERTAIN THE LEFT WING FUEL PUMPS WOULD WORK PROPERLY. WE ELECTED TO DECLARE AN EMERGENCY AND DIVERT TO ZZZ WHICH WAS THE CLOSEST AIRPORT. WE LANDED IN ZZZ UNEVENTFULLY; AND TAXIED TO THE GATE. WE HAD OVER A 7000 LB IMBALANCE AT THE GATE.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE REPORTER STATED THAT HIS ACR GROUNDED THIS ACFT UPON ARRIVAL AND BEGAN AN IN-DEPTH INVESTIGATION. ONE OF THE FIRST ABNORMAL CONDITIONS NOTED WAS THE UNDERWING FUELING PANEL SWITCHES WERE NOT IN THE CORRECT POSITIONS. ADDITIONALLY; THE WING TANKS WERE OPENED TO ALLOW FOR EXAMINATION OF THE FUELING SYSTEM COMPONENTS. THE PUMP SWITCHES ON THE INNER TANKS WERE CHANGED. THE REPORTER DID NOT HAVE THE FINAL MAINTENANCE DEPARTMENT CONCLUSION ABOUT WHAT ACTUALLY FAILED.

Data retrieved from NASA's ASRS site as of May 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.