A B747-400F IN CLB AT 16000 FT TO FL200 DECLARED AN EMER AND DIVERTED DUE TO FLAP RETRACTION FROM POS '1' TO 'UP' THE STICK SHAKER. CAUSING REPEATED SEVERAL TIMES.

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ALL TKOF PREPARATIONS WERE COMPLETED UP TO FINAL FLT DECK PROC. WE INPUTTED ZFW DATA AS PER FOM INTO THE FMS; THE ZERO FUEL WT WAS 270.2 TONS AND FUEL ON BOARD 108.2 TONS. COMPLETED PUSHBACK AND TAXI. ALL CHKLISTS COMPLETE. NORMAL MAX THRUST DEP ON THE NAROK B SID RWY 6 TO FL310. DEP SPDS AS COMPUTED BY THE CREW MEMBERS V1 150; VR 167; V2 177. THE FMC SPDS CONFIRMED AND ENTERED AT V1 151; VR 168; V2 179. CLRED FOR TKOF; THE ENG PARAMETER NORMAL AND TKOF NORMAL. ON CLBOUT; ACFT WAS STABLE AT V2 +15 KTS (+/-1 KT); THEN NOTED THAT TARGET COMMAND SPD BUG ACCELERATED ON ITS OWN ACCORD TO V2 +23 KTS AT 300 FT RA. REST OF CLBOUT NORMAL ON NAROK B SID UNTIL FLAP RETRACTION FROM POS '1' TO 'UP' AT APPROX 270 KIAS ON PFD. SPD INDICATED APPROX FLAPS UP SPD AND INCREASING; BEFORE CALLING FOR FLAPS RETRACTION. IMMEDIATELY UPON MOVEMENT OF FLAP TO 'UP;' STICK SHAKER ACTIVATED AS LOW AND HIGH SPD BUFFET MARGIN MERGED AT RAPID RATE. IMMEDIATELY CALLED FOR MAX THRUST AND FLAPS EXTENSION BACK TO POS #1. STICK SHAKER CEASED; BUFFET SPD TAPES SEPARATED TO WITHIN SAFE MARGINS FOR FLAP POS. ACFT CLBING IN LIGHT TURB IN IMC; CUMULONIMBUS IN THE VICINITY. WHEN CLR OF THE WX APPROX 3 MINS; REPEATED FLAP RETRACTION WITH SAME RESULT. NO EICAS AND NO STATUS MESSAGE DISPLAYED. ACFT AT ABOUT FL180 CLBING INTERMEDIATE LEVELOFF REQUESTED AND APPROVED. AT FL200 CREW IN CONCERT RESEARCHED QRH; PERFORMANCE DATA AND ACFT FLT MANUAL. ENGINEER WAS SUMMONED TO ASSIST IN EVALUATION OF SIT. REQUESTED RETURN TO NBO; ENRTE ACFT STABLE AND AUTOPLT ON. LAST ATTEMPT TO RETRACT FLAPS WAS MADE; WITH THE SAME RESULT. ACFT WAS CLRED TO DSND TO 12000 FT. DUE TO TERRAIN; STOPPED DSCNT AT 15000 FT. SATCOM WAS ESTABLISHED WITH ACR DISPATCH AND MAINT. INFORMED OF SIT TO DUMP FUEL AND LAND AT NBO IN CONCURRENCE WITH DISPATCH. FLEW INITIALLY TOWARDS GG; DUE TO WX ELECTED TO HOLD AT NV AT 15000 FT; INITIATED FUEL DUMP PER QRH AND DECLARED EMER. DURING DUMPING; APPROX 40 MINS; MADE NUMEROUS ATTEMPTS TO CONTACT ACR OPS ON SATCOM UNSUCCESSFULLY DUE TO PHONE NUMBER BEING 'NOT AUTH.' DUE TO ENCROACHING CUMULONIMBUS APCHING ARPT AND FUEL GRAVITY XFER VALVE PROB; RESULTING IN FUEL IMBAL; DUMPING WAS TERMINATED AND DECISION TO LAND OVERWT WAS MADE FOR TOUCHDOWN AT 305.1 TONS FMC WT WAS MADE. DURING DUMPING; IT WAS DISCOVERED THAT CAPT AND FO PFD INDICATED AIRSPD WERE IN AGREEMENT. HOWEVER; THEIR INFO WAS APPROX 15 KTS HIGHER THAN THE STANDBY AIRSPD INDICATOR. BASED ON THE ABOVE INFO AND CREW ASSUMPTION BY ALL AVAILABLE INFO; THAT WE WERE AT A HIGHER WT THAN PREDICTED OR HAD FLT COMPUTER SYS PROB; A VREF SPD WAS MANUALLY CALCULATED ON CURRENT CONDITION. LNDG WAS ACCOMPLISHED AT FLAPS 30 DEGS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THAT EVERY ATTEMPT TO RAISE THE FLAPS FROM POS #1 TO FULL 'UP' RESULTED IN STICK SHAKER ACTION. THE RPTR SAID ALL ACFT FLT PARAMETERS WERE IN NORMAL CONFIGN. THE RPTR STATED THE AIRPLANE WAS MAINT FERRIED FROM NAIROBI BY A TEST FLC AND NO INFO WAS RELEASED BY MAINT ON ACTION TAKEN. THE RPTR SAID IT WAS SUSPECTED THE ANGLE OF ATTACK SENSORS MAY BE INVOLVED BUT THIS IS JUST SPECULATION AND ONLY BECAUSE A EUROPEAN B747-400F WAS INVOLVED IN THE SAME TYPE OF INCIDENT.