B747-400 STAB GREENBAND WARNING ILLUMINATES ON PUSHBACK. MAINTENANCE DEFERS NOSE GEAR SENSOR. ANOMALOUS AIRSPEED/PFD DATA ON LANDING CAUSES FLIGHT CREW TO SUSPECT AIRCRAFT WAS HEAVIER THAN ADVISED BY LOAD PLANNING AND THAT THE WARNING MAY HAVE BEEN ACCURATE.

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ON PUSHBACK IN ZSPD WE GOT THE STAB GREENBAND ADVISORY AND STATUS MESSAGES WITH THE STABILIZER ADDITIONAL NOSE UP TRIM GREENBAND VISIBLE. WE VERIFIED OUR WT AND BAL INPUT INTO THE FMC WERE CORRECT AND COULD NOT DETERMINE THE CAUSE OF THE MESSAGES SO WE DID A BLOCK TURN BACK. ZSPD MAINT DID SOME CHKS AND SAID THE NOSE GEAR PRESSURE SENSOR WAS INOP AND BEGAN DEFERRING IT IN THE ACFT LOGBOOK. UPON QUESTIONING MAINT BY US (THE CREW) THEY GOT THE ZSPD MAINT SUPVR ON THE PHONE TO EXPLAIN THE TESTING AND DEFERRAL TO US. WITH THE LANGUAGE BARRIER WE GOT ZZZ MAINT; ZZZ FLT CTL; AND THE ZZZ CHIEF PLT ON DUTY INTO THE LOOP. ZSPD SAID THEY RECHKED THE WT AND BAL INFO. WE WERE ASSURED THE LOAD WAS CORRECT AND WERE GIVEN A CLEAN LOGBOOK WITH THE NOSE GEAR PRESSURE SENSOR DEFERRED. SO WE DEPARTED. WHILE ON APCH WHEN WE SELECTED THE FLAPS 20 KT SPD WE NOTICED THE FMC GENERATED FLAP 20 KT SPD WAS BELOW THE AIR DATA COMPUTER GENERATED YELLOW MINIMUM MANEUVERING SPD INDICATOR. THE SAME WAS NOTICED FOR THE FLAP 30 VREF SPD. IT ALSO APPEARED TO BE A HIGHER THAN NORMAL DECK ANGLE SO THE SPD WAS BUGGED UP TO GIVE A NORMAL DECK ATTITUDE FOR LNDG. WE LANDED WITHOUT EVENT. AFTER SHUTDOWN IN THE BLOCKS IT APPEARED THAT WE HAD FUEL BURN FOR A HEAVIER LOAD THAN WHAT WAS ON THE WT AND BAL. THE WT AND BAL THAT WE WERE GIVEN WAS FOR APPROX 20000 LBS LESS WT THAN THAT ESTIMATED ON OUR FLT PLAN. WE GAVE THIS INFO TO THE CHIEF PLT ON DUTY.