THE L LNDG GEAR DOWN LOCK PIN IS LEFT IN ON AN SF340 AND FAILS TO RETRACT AFTER TKOF FROM CMX; MI.

Narrative

THE STATION MGR PUSHED OUR AIRPLANE OUT OF THE HANGAR PART WAY AND WAS STUCK IN ICE. THE CAPT AND MYSELF GOT INTO THE PLANE; AND THE STATION MGR PUSHED THE PLANE A LITTLE FARTHER. THE CAPT THEN STARTED BOTH ENGS AND BEGAN A L TURN WHEN HE NOTICED SHE HAD NOT TAKEN OUT THE NOSEWHEEL PIN. THE CAPT CALLED HER BACK AND SHE TOOK THE NOSEWHEEL PIN OUT. SHE THEN DISAPPEARED ON THE L SIDE OF THE AIRPLANE. SHE THEN REAPPEARED WALKING AROUND THE NOSE OF THE PLANE HEADING TOWARD THE R SIDE. I BELIEVED SHE HAD TAKEN THE L MAIN GEAR PIN OUT AND WAS GOING TO ALSO TAKE THE R MAIN GEAR PIN OUT. THE CAPT AND I MOTIONED FOR HER NOT TO TAKE THE R GEAR PIN OUT AS THE PROPS WERE SPINNING. SHE HANDED WHAT I BELIEVED WERE THE NOSE GEAR PIN AND LEFT MAIN GEAR PIN TO THE CAPT AND LEFT. THE CAPT; THEN TAXIED TO THE GATE. AFTER WE SHUT DOWN THE ENGS AND DID A SHUTDOWN CHKLIST; I EXITED THE AIRPLANE AND DID A PREFLT. I TOOK THE R MAIN GEAR PIN OUT DURING THE PREFLT. WHEN I GOT TO THE L MAIN GEAR; I DOUBLE CHKED FOR THE GEAR PIN EVEN THOUGH I BELIEVED IT WAS OUT. I DID NOT SEE IT. AFTER TKOF; THE CAPT ATTEMPTED TO RETRACT THE GEAR AS PER OUR FLOW. THE L MAIN GEAR FAILED TO RETRACT ON THAT AND 2 MORE ATTEMPTS. THE CAPT ASKED ME IF I WAS SURE THE L MAIN GEAR PIN WAS OUT AND I TOLD HIM I HAD CHKED IT AND THOUGHT IT WAS OUT. THE CAPT CONTACTED ZMP AND TOLD THEM WE WOULD BE LNDG IN HOUGHTON/HANCOCK. ZMP VECTORED US FOR A VISUAL APCH AND WE LANDED WITHOUT INCIDENT. UPON LNDG; I CHKED THE L MAIN GEAR AND FOUND THE GEAR PIN. THE FLAG WHICH NORMALLY HANGS DOWN WAS WADDED UP AND WAS NOT HANGING DOWN. SUPPLEMENTAL INFO FROM ACN 540999: UPON ARR AT THE GATE THE FO COMMENCED HIS PREFLT. I TOLD HIM PRIOR THAT THE GEAR PINS WERE INSTALLED AT EVERY OVERNIGHT AND HE WOULD HAVE TO REMOVE THEM. HE RE-ENTERED THE COCKPIT AS I WAS DOING BY PRE-DEP FLOW PATTERN. HE ASKED ME TO SLIDE MY SEAT FORWARD SO HE MAY STOW THE PINS. I DID THIS; AND QUICKLY GLANCED BACK AT HIM TO SEE WHAT APPEARED TO BE GEAR PINS IN HIS HAND. I ALSO HEARD THE DISTINCT NOISE THE PINS MAKE AS YOU SLIDE THEM INTO THE RACK. AS WE PERFORMED THE ACCEPTANCE CHKLIST; ON THE CHALLENGE 'GEAR PINS AND NOSE LOCKOUT CLAMP;' I LOOKED BACK TO THE SPOT WHERE THEY ARE STOWED; SAW 2 PINS; AND A RED FLAG (SUCH AS THE ONE LIKE IS ATTACHED TO THE PINS); FOR A TOTAL OF 3. THIS COMBINED WITH THE FO ASKING ME TO SLIDE MY SEAT FORWARD AND NOTICING WHAT APPEARED TO BE GEAR PINS IN HIS HAND CONVINCED ME THEY WERE ALL ABOARD. I ALSO PHYSICALLY TOUCHED THE NOSE PIN; 1 MAIN GEAR PIN AND THE FLAG FROM WHAT I THOUGHT WAS THE 3RD PIN; THE AREA WAS OBSCURED BY MY HANGING OVERCOAT; BUT I MOVED IT; AND IT IS MY PERSONAL PROC TO TOUCH THE PINS TO BE SURE THEY ARE ABOARD. THE RED FLAG WHICH I HAD MISTAKEN FOR THE 3RD GEAR PIN IN THE COCKPIT ON THE CHKLIST WAS ACTUALLY A PITOT TUBE COVER WITH A SIMILAR OR SAME RED FLAG ON IT. WHEN I ASKED THE FO WHY HE REMOVED 1 GEAR PIN FROM THE R MAIN GEAR AND NOT THE OTHER; HE RESPONDED HE FORGOT TO DO SO.