AN A319 MCDU WOULD NOT ACCEPT CG NUMBERS AFTER ENG START AND DID NOT CALCULATE A ZFWCG. FINAL WT AND BALANCE NUMBER USAGE PRODUCED AN EARLY ROTATION DURING TKOF.

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AFTER PUSHBACK WE RECEIVED THE WT AND BAL RPT AND WAITED UNTIL THE SECOND ENG START TO ENTER THE INFO ON FUEL PREDICTION PAGE. THE FO TRIED TO ENTER 154579/28.7 AT L3 ON THE PAGE. THE MCDU WOULD NOT TAKE THE FULL INFO. IT WOULD TAKE THE WT BUT NOT THE CTR OF GRAVITY NUMBER. AT RWY 4R UNDER THE ZFW/ZWCG WE SAW AMBER BOXES. WE TRIED SEVERAL TIMES TO ENTER THE INFO; BUT ALL THE MCDU WOULD TAKE WAS THE WT AND NOT THE CTR OF GRAVITY/MACH NUMBER. WE DID NOTICE THAT THE ZFW SHOWED 118308; BUT THE ZFWCG WAS BLANK. WE CALLED MAINT CTL AND THEY COULD NOT HELP. THEY SUGGESTED WE CALL THE CHIEF PLT. I DID AND HE TOLD ME HE WOULD HAVE SOMEONE CALL ME ON MY CELL. I TALKED WITH THE CALLER AND I EXPLAINED TO HIM WE HAD TRIED EVERYTHING WE COULD THINK OF TO MAKE IT WORK (POWERING DOWN; SHUTTING DOWN ENGS AND RESTARTING) BUT NOTHING WORKED. FINALLY; HE SAID FOR ME TO JUST PUT THE 28.7 NUMBER IN THE ZFWCG. I TOLD HIM I WAS UNCOMFORTABLE DOING THAT BUT WOULD DO IT ON HIS ORDER. I EXPLAINED TO HIM THAT WE WERE NOT JOINTLY DISPATCHING THIS ACFT SINCE I FELT WE WERE IN UNCHARTED WATERS. WE ENTERED 28.7 IN THE ZFWCG AND SET THE TRIM STABILIZER TRIM AT 0.3U. NOW THE FUN BEGINS TO THIS STORY. AS WERE IN THE PROCESS OF TAKING OFF AT APPROX 10 KTS PRIOR TO V1 WHICH WAS SET IN THE MCDU ON THE PERFORMANCE PAGE AT 136 KTS THE NOSE OF THE AIRPLANE STARTED TO PITCH UP. I STARTED APPLYING NOSE DOWN PRESSURE ON THE STICK AND HELD THE AIRPLANE ON THE GND UNTIL VR WHICH WAS 140 KTS. AS THE AIRPLANE LIFTED OFF AND AFTER THE WHEELS WERE IN THE WELLS WE RECEIVED AN AMBER MESSAGE ON THE SCRATCHPAD OF THE MCDU THAT SAID 'CG' IN AMBER LETTERS. I COULD SENSE THE AIRPLANE RETRIMMING ITSELF AS WE CLBED OUT THROUGH 1000 FT. THE REST OF THE TRIP WAS NORMAL.