A B757-200 IMMEDIATELY AFTER TKOF DECLARED AN EMER AND RETURNED TO THE FIELD DUE TO UNABLE TO RETRACT THE NOSE LNDG GEAR CAUSED BY LOCK PIN INSTALLED.

Narrative

THE NIGHT BEFORE THE OCCURRENCE THE ACFT HAD WORK PERFORMED ON THE BRAKES WHICH REQUIRED TOWING. THE WORK WAS DONE AND SIGNED OFF. THEN THERE WAS A MAINT CREW CHANGE AND THE ACFT WAS TOWED BACK TO THE GATE. THE REQUIRED LOGBOOK WRITE-UP NOTING INSTALLATION OF THE NOSE GEAR PIN WAS NOT MADE. THE NEW TOW CREW DID NOT CHK FOR A PIN SINCE THERE WAS NO WRITE-UP. THE INSTALLED PIN HAD A NONSTANDARD LENGTH STREAMER ATTACHED AND WAS ALSO COVERED WITH GREASE; MAKING IT APPEAR BLACK INSTEAD OF RED. IN THE EARLY MORNING HR WITH AN OVCST SKY THE FO MISSED SEEING THE PIN ON HIS WALKAROUND. SUBSEQUENT TKOF A GEAR RETRACTION REVEALED THE NOSE GEAR STILL DOWN AND LOCKED. TRIED RECYCLING THE GEAR AND THEN PLANNED TO RETURN TO ZZZ. MAINT CTL SUGGESTED XXX FOR BETTER MAINT. WE STARTED UP THAT WAY UNTIL CHKING THE WX AND DISCOVERING IT WAS BELOW MY HIGH MINIMUMS (NEW CAPT). AN OVERWT LNDG WAS APPROVED BACK AT ZZZ; BUT AFTER DISCUSSING THE CURRENT WT; I DECIDED TO HOLD TO REDUCE THE WT BELOW MAX LNDG LIMIT. THIS WAS DONE WITH THE GEAR DOWN AND PARTIAL SPOILERS AT V2F. THE PAX WERE BRIEFED SEVERAL TIMES AS WELL AS LCL STATION OPS. AN UNEVENTFUL LNDG WAS MADE 2000 LBS BELOW OUR MAX LNDG WT. AT THE GATE THE GND CREW FOUND THE PIN IN THE NOSE GEAR. THEN WE WERE BRIEFED BY THE STATION MGR AS TO THE EVENTS THAT LED UP TO THIS SIT.