B727 HAS GEAR THAT WILL NOT RETRACT AFTER TKOF FROM LGA; NY. FUEL IS DUMPED; LNDG IS NORMAL BUT SMOKE IN CABIN CAUSES AN EVAC AFTER SHORT TIME ON THE GND.

Narrative

THE LNDG GEAR FAILED TO RETRACT ON TKOF. THE LNDG GEAR LEVER WOULD NOT MOVE TO THE 'UP' POS AND WAS LEFT IN THE 'OFF' POS. ATC WAS INFORMED IMMEDIATELY. I FLEW THE ACFT AND THE CAPT AND SO REVIEWED THE ABNORMAL PROCS FOR LNDG GEAR MALFUNCTIONS. WHEN THE ABNORMAL PROCS WERE FOLLOWED AND FAILED TO CORRECT THE SIT; THE CAPT ELECTED TO DUMP FUEL TO BRING THE ACFT DOWN TO A SAFE LNDG WT; AND RETURN TO LAGUARDIA FOR LNDG. AFTER COORDINATING WITH ATC AND DUMPING FUEL; ALL NORMAL CHKLISTS WERE COMPLETED; AND A NORMAL VISUAL APCH WAS MADE TO RWY 4. ROLLOUT WAS COMPLETED WITH THE ACFT COMING TO A COMPLETE STOP IN 5000 FT OF RWY. WE HELD POS ON THE RWY WHILE EMER CREWS WERE INSPECTING AND SAFETY-PINNING THE LNDG GEAR PRIOR TO FURTHER TAXI. SUPPLEMENTAL INFO FROM ACN 467051: DURING THIS ACTIVITY A FLT ATTENDANT RPTED LIGHT SMOKE LIKE A FOG WITH A RUBBERY OILY SMELL IN THE CABIN. AS THE CABIN DOOR HAD BEEN OPENED AFTER THE AIR CAME TO A STOP I VISUALLY CONFIRMED THE PRESENCE OF VERY LIGHT SMOKE IN THE CABIN. I SCANNED THE ENGINEERS PANEL AND NOTED A PACK TRIP LIGHT FOR THE OPERATING AIR CONDITIONING PACK; WHICH I IMMEDIATELY SECURED. THE CAPT ELECTED TO EVAC THE ACFT THROUGH THE MAIN DOORS AND ORDERED THE EMER EVAC CHKLIST ACCOMPLISHED. WE RAN THE CHKLIST AND COMMENCED THE EVAC. THE FO AND MYSELF COMPLETED OUR COCKPIT DUTIES AND EXITED THE ACFT TO ASSIST THE PAX.