ACR CREW DEPARTS WITHOUT FULL UNDERSTANDING OF A FUEL SYS PROB THAT IS DEFERRED PER THE MEL.

Narrative

WE PICKED UP THE AIRPLANE FOR THE FIRST FLT OF THE DAY OUT OF BOS TO CLT. I CHKED THE LOGBOOK AND FLT RELEASE PAPERWORK AND NOTICED THAT THERE WAS AN MEL ON THE AFT CTR FUEL TANK BOOST PUMP. THE ACFT HAD 24600 LBS OF FUEL ONBOARD -- 9300 LBS IN EACH WING TANK; AND ABOUT 6000 LBS IN THE CTR TANK. THE RELEASE ALSO HAD A NOTE/REMARKS THAT SAID '150 LBS TRAPPED IN CTR TANK.' I KNEW THAT THERE WAS A PROC IN THE QRH TO USE CTR TANK FUEL WITH EITHER THE FORWARD OR AFT CTR TANK BOOST PUMP INOP. AND BECAUSE THE ACFT WAS RELEASED WITH THE FUEL STATE ONBOARD; I ASSUMED THAT THIS PROC WAS WHAT WE WERE EXPECTED TO ACCOMPLISH FOR THIS FLT. AS TO THE REMARK ON THE RELEASE ABOUT '150 LBS TRAPPED IN CTR TANK;' I THOUGHT IT MUST MEAN THAT AFTER CTR TANK FUEL WAS USED; 150 LBS WOULD REMAIN IN THE TANK AND BE UNUSABLE WHEN OPERATING WITH ONLY THE FORWARD BOOST PUMP. ALSO; THE ORIGINAL WRITE-UP ON THE AFT BOOST PUMP REFERRED TO THE QRH PROC BEING USED TO BURN THE CTR TANK FUEL. THEREFORE; AT THIS TIME I WAS NOT TOO CONCERNED ABOUT HAVING FUEL IN THE CTR TANK. MY NEXT THOUGHT WAS TO CHK THE MEL BOOK TO SEE WHAT IT SAID. AT THIS TIME THINGS GOT BUSY -- THE FLT ATTENDANTS NEEDED SOMETHING; AND AS I WAS ABOUT TO GET THE MEL BOOK A JUMP SEAT RIDER SHOWED UP AND I WAS DISTRACTED WITH THAT. THEN THE AGENT WAS STANDING THERE IN A HURRY TO GET THE FLT OFF THE GATE. WHAT THIS ALL LED TO WAS ME NOT GETTING TO CHK THE MEL BOOK. AS WE WERE CLBING OUT OF BOS I STARTED THE QRH PROC FOR THE CTR TANK FUEL. AT FIRST IT DIDN'T SEEM TO BE COMING OUT OF THE CTR TANK. AT THAT POINT I THOUGHT OF THE MEL BOOK THAT I DIDN'T GET TO CHK; SO I ASKED THE FO TO HAND IT TO ME (IT IS STORED OVER ON THE R-SIDE OF THE COCKPIT). WHEN I LOOKED AT THE MEL FOR THE CTR TANK PUMP I HAD TO READ IT AGAIN TO MAKE SURE I WAS UNDERSTANDING IT CORRECTLY; AND I BECAME CONCERNED BECAUSE IT SAID THAT WITH AN INOP CTR TANK PUMP; 'CONSIDER CTR TANK FUEL UNUSABLE.' WE WOULD NEED THAT 6000 LBS TO COMPLETE THE FLT. AT THIS POINT I REALIZED THAT SOMETHING WASN'T RIGHT HERE; SO I MADE A CALL TO THE DISPATCHER AND TOLD HIM WHAT THE SIT WAS. I'M THINKING; 'WHY WOULD WE GET RELEASED WITH 6000 LBS OF FUEL IN THE CTR TANK IF IT WAS UNUSABLE?' HOWEVER; NOW THE CTR TANK FUEL WAS COMING OUT OF THE CTR TANK LIKE IT WAS SUPPOSED TO AS A RESULT OF THE QRH PROC I WAS USING. I TOLD THE DISPATCHER THAT THERE WAS NOT GOING TO BE A PROB WITH CONTINUING TO OUR DEST BECAUSE THE CTR FUEL WAS AVAILABLE TO US AFTER ALL. (I THINK THAT AT FIRST THE NOSE ATTITUDE OF THE ACFT MADE THE CTR TANK FUEL QUANTITY APPEAR TO BE NOT DECREASING.) WE CONTINUED TO CLT UNEVENTFULLY; AND LANDED WITH ABOUT 9000 LBS OF FUEL IN THE WING TANKS AND ABOUT 1900 LBS LEFT IN THE CTR TANK. LESSON LEARNED: NO MATTER WHAT THE MEL OR HOW FAMILIAR YOU THINK YOU ARE WITH IT; CHK THE BOOK.