A300 FLT CREW RETURNS TO DEP ARPT DUE TO ECAM TRIM TANK FUEL XFER FAIL MESSAGE. AFTER LNDG DETERMINE THEY HAD MISDIAGNOSED THE PROB AND UTILIZED INAPPROPRIATE CHKLISTS.

Narrative

DURING CLBOUT; WE RECEIVED A TRIM TANK XFER FAIL MESSAGE. REFERRING TO THE QRH; WE RAN THE TRIM TANK SYSTEM FAULT PROC. NOTING THAT THERE WAS NO FORWARD FUEL XFER BECAUSE THE SYSTEM HAD FAILED; THE CHKLIST HAD US PROCEED TO THE TRIM TANK FUEL UNUSABLE PROC. AFTER RUNNING THIS CHKLIST; WE OBSERVED THE CAUTIONARY STATEMENT TO CONSIDER DIVERTING DUE TO THE CTR OF GRAVITY BEING OUT OF LIMIT FOR LNDG WHEN THE INNER TANKS BURN BELOW 17.7K LBS. THE CAPT GOT ON THE RADIO WITH MAINT TO DISCUSS THE ISSUE. THEN HE TALKED TO FLT CTL/DISPATCH. DURING THIS TIME; I WAS FLYING THE ACFT AND WORKING THE ATC RADIO. WHEN THE CAPT RETURNED FROM TALKING WITH MAINT AND DISPATCH; WE OBTAINED A CLRNC FROM ATC TO RETURN TO ZZZ. WE DISCUSSED THE NEED TO LAND BEFORE REACHING THIS CTR OF GRAVITY IMBALANCE AND WHETHER OR NOT WE WOULD NEED TO PERFORM AN OVERWT LNDG. DURING THE ARR; THE CHIEF PLT CAME OVER THE RADIO AND AFTER ANALYZING OUR SITUATION; DEEMED THE CTR OF GRAVITY IMBALANCE WAS NOT AN ISSUE. WE CONTINUED TO BURN FUEL DOWN TO BELOW MAX LNDG WT AND RETURNED UNEVENTFULLY. LESSONS LEARNED: IN HINDSIGHT; SEVERAL FACTORS LED US DOWN THE POSSIBILITY OF RUNNING THE WRONG CHKLIST AND THE DECISION TO PERFORM AN AIR TURNBACK: 1) WHEN THE INITIAL ECAM MESSAGE HAD APPEARED; THERE WAS NO REF BY THE ECAM TO A SPECIFIC PROC. AFTER LNDG AND DEBRIEFING WITH THE CAPT; I LEARNED THAT HE THOUGHT THERE WAS AN ECAM SPECIFIC REF TO A PROC. I HAD TURNED TO THE MOST APPLICABLE QRH PROC: TRIM TANK SYSTEM FAULT. I READ THE TITLE TO VERIFY WE WERE ON THE PROPER CHKLIST PROC; BUT SINCE THE CAPT THOUGHT THE ECAM REFERENCED US THERE; HE KNEW WE WERE ON THE PROPER CHKLIST. LOOKING BACK; WHAT I COULD HAVE DONE WAS QUERY THE CAPT AS TO WHETHER OR NOT WE HAD TO RUN THIS CHKLIST PROC; SINCE THE ECAM DIDN'T REF US TO AN ACTUAL PROC. 2) EVEN SO; IF WE HAD RUN THE TRIM TANK SYSTEM FAULT CHKLIST PROPERLY; WE WOULD HAVE JUST MATCHED SWITCHES WITH THE TRIM TANK FAULT AND BE DONE WITH THE PROB. HOWEVER; WHEN THE QRH ASKED IF THERE WAS NO FORWARD FUEL XFER; I MAY HAVE MISDIAGNOSED THE AMBER TRIANGLE SYMBOLS ON THE FUEL PAGE AS CONFIRMATION THAT THERE WAS NO FORWARD FUEL XFER; WHICH SENT US TO THE TRIM TANK FUEL UNUSABLE CHKLIST. 3) AFTER LNDG AND DISCUSSING WITH THE CAPT; I REALIZED THAT WE SHOULDN'T HAVE BEEN ON THIS SECOND CHKLIST BECAUSE THERE WAS NO FUEL REMAINING IN THE TRIM TANK. AT THAT POINT; THE DECISION TO TURN BACK WAS ALREADY MADE AND WE WERE WELL ESTABLISHED ON THE ARR. 4) AS WE RAN THE TRIM TANK FUEL UNUSABLE CHKLIST; WE BOTH TURNED OUT ATTN TO THE CAUTIONARY STATEMENT ABOUT THE CTR OF GRAVITY BEING OUT OF LIMIT FOR LNDG IF WE BURN TOO MUCH OUT OF THE INNER TANKS. FROM HERE; WE FELT AT THE TIME WE WERE MAKING THE MOST CONSERVATIVE AND SAFE DECISION BY RETURNING TO LAND. SUPPLEMENTAL INFO FROM ACN 811566: I MAY HAVE COME TO A DIFFERENT CONCLUSION ON MY DECISION IF I HAD MORE INPUT EARLIER FROM MAINT AND FLT CTL. DUE TO MAINTAINING SAFETY OF FLT; I FELT THIS WAS THE BEST COURSE OF ACTION AT THE TIME. CONSIDERING ALL AVAILABLE RESOURCES MADE AVAILABLE TO US; WE MADE THE DECISION TO RETURN.