LTT CARGO ACFT HAS NOSE GEAR UNSAFE LIGHT ACTIVATE JUST AFTER TKOF. CONTINUED WITH GEAR EXTENDED.

Narrative

WE HAD JUST TAKEN OFF FROM PDX 28R BOUND FOR BFI (SEATTLE); WHEN WE NOTICED FIRST BY SOUND AND THEN NOSE GEAR UNSAFE LIGHT STAYED ON. I IMMEDIATELY SUSPECTED PROBS WITH THE NOSE GEAR AND CALLED FOR GEAR DOWN. WE HAD THEN NORMAL 3 GREEN DOWN AND LOCKED. HOWEVER; I DECIDED TO LEAVE GEAR DOWN TO MY DEST; BFI; APPROX; 130 NM AND 30 MIN FLYING TIME. I ADVISED ATC ABOUT OUR POTENTIAL PROB AND TOLD THEM ABOUT MY REDUCED SPD AT CRUISE LEVEL (200 KIAS) AT 20000 FT. WHEN WE CONTACTED BOEING FIELD TWR; WE ADVISED THEM ABOUT NOSE GEAR AND ASKED THEM TO LOOK FOR ANYTHING UNUSUAL. THEY SAID ALL 3 GEARS WERE DOWN AND LOOKED NORMAL. THIS WAS CONFIRMED BY A B-737 CREW READY TO DEPART 13R. WE SLOWED THE ACFT TO MINIMUM SPD AND AFTER TOUCH DOWN; WE KEPT THE NOSE GEAR UP AS LONG AS POSSIBLE. WHEN WE WERE ABOUT TO LOWER THE NOSE GEAR; TWR SAID SOMETHING ABOUT THE NOSE WHEEL NOT BEING CTRED. BY THEN; THE NOSE GEAR WHEEL TOUCHED DOWN AND THE AIRPLANE IMMEDIATELY STARTED TO TURN L. I USED MAX BRAKING; WITH MORE OPPOSITE R BRAKE TO TRY NOT TO GO FAR OFF CTRLINE. ACFT CAME TO A COMPLETE STOP BTWN RWY EDGE LIGHTS AND CTRLINE. NOSE STEERING WAS NOT WORKING AND I DECIDED TO SHUT DOWN BOTH ENGS AND GO OUTSIDE THE ACFT TO INSPECT THE NOSE GEAR; AND THEN WE CALLED FOR A TOW TRUCK. THE TWR CLOSED THE RWY FOR ABOUT 15-20 MIN. THE REASON THE GEAR WOULDN'T COME UP WAS BECAUSE THE NOSE GEAR STRUT HAD COLLAPSED (DEFLATED).