A DC-10-10 ON TKOF CLB BTWN 4000 FT AND 5000 FT DECLARED AN EMER AND DIVERTED DUE TO LOSS OF TRAILING EDGE FLAP CTL. CAUSED BY A FAILED FLAP CTL VALVE.

Narrative

AFTER DEPARTING ZZZ RWY 9L SELECTING FLAPS TO 0/EXT FLAP TAPES REMAINED IN THE TKOF SETTING. ZZZ MAINT ASKED US TO PERFORM CERTAIN TASKS ALL HAD NO EFFECT ON THE FLAP POSITION TAPES. WE WERE INSTRUCTED TO RETURN TO ZZZ. AFTER CHECKING THAT THE RWY LENGTH WAS SUITABLE FOR OUR LNDG CONFIGURATION WE NOTIFIED ATC; DECLARED AN EMER; AND COMMENCED A FUEL DUMP TO REDUCE OUR LNDG WT. WE COMMENCED AN APCH FOR RWY 9L ZZZ 0/EXT LNDG. ON TAXI IN AFTER ACCOMPLISHING THE 'AFTER LNDG CHKLIST' WHICH CALLS FOR FLAPS UP SLATS RETRACT; THE FLAP TAPES DROPPED TO 30 WHICH WAS CONFIRMED BY ZZZ MAINT UPON ARR AT THE GATE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED BTWN 4000 FT AND 5000 FT WHEN THE FLAP HANDLE WAS PLACED TO UP THE TRAILING EDGE FLAPS REMAINED AT THE TKOF POSITION. THE RPTR SAID MAINT REQUESTED SEVERAL CHECKS BE ACCOMPLISHED PRIOR TO RETURNING TO THE FIELD WHICH WERE ACCOMPLISHED. THE RPTR STATED FUEL WAS DUMPED TO THE DUMP LIMITS AND THE AIRPLANE WAS LANDED WITHIN WT LIMITS. THE RPTR STATED ON THE GND WITH THE FLAP HANDLE IN FULL RETRACT 0 DEGS FLAP THE FLAPS EXTENDED TO 30 DEGS AND REMAINED IN THIS POS. THE RPTR SAID MAINT WAS UPSET WITH THE CREW ABOUT THE DECLARED EMER; AS THEY WOULD NOW BE FORCED TO CORRECT THE FLAP PROB; AND THEY WERE NOW CHECKING OK ON THE GND. THE RPTR SAID THE PROB WAS CORRECTED WITH A FLAP CTL VALVE REPLACEMENT.