AFTER TKOF THE NOSEWHEEL WOULD NOT RETRACT OR SUBSEQUENTLY LOCK IN THE DOWN POS.

Narrative

THE CAPT CALLED FOR GEAR RETRACTION ON TKOF FROM RDU -- A POP/SNAP SOUND WAS HEARD AS THE GEAR LEVER WAS RAISED. THE MAIN GEAR RETRACTED NORMALLY BUT; AS THE NOSE GEAR APCHED THE 'UP' POS; AN EXTREMELY LOUD NOISE (AIRSTREAM) AND HVY VIBRATION WERE EXPERIENCED. BY RETURNING THE GEAR HANDLE TO 'UP LATCH;' ONLY THE VIBRATION DISAPPEARED. WE CLBED TO 10000 FT ON VECTORS FROM RDU DEP AND MAINTAINED A 20 NM BOX PATTERN AROUND THE VOR FOR THE NEXT 3 HRS. DURING THAT TIME; WE DECLARED AN EMER AND SUBSEQUENT ATTEMPTS AT SLOW FLT; SPDING UP; CYCLING AND VIEWING GEAR POS FAILED TO GET THE NOSE GEAR EITHER UP AND LOCKED OR DOWN AND LOCKED. WE BRIEFED THE PAX ACCORDINGLY AND; AFTER BURNING DOWN THE FUEL; WE COMMENCED WHAT WE BELIEVED WOULD BE A NOSE GEAR UP LNDG. SUBSEQUENTLY; WE LANDED AND UPON LOWERING THE NOSE; DISCOVERED THE NOSE GEAR HELD FIRM. SPECULATION; AT THIS POINT; HAS IT THAT THE NOSE GEAR WAS SOMEHOW ENTANGLED IN A GEAR DOOR CABLE AND THE LNDG FREED THE GEAR TO LOCK OVER CTR. RDU CTLRS AND GND PERSONNEL WERE EXTREMELY HELPFUL AND AS FAR AS ANYONE IN THE CREW WAS AWARE; THERE WERE NO ADDITIONAL CONFLICTS.