A HVY FREIGHTER HAS TO RETURN LAND AT DAL WHEN THEIR R MAIN GEAR INDICATES AN UNSAFE CONDITION. CREW WAS UNABLE TO RETRACT THAT GEAR.

Narrative

AFTER THE TKOF; DURING THE AFTER TKOF CHKLIST; A GEAR UNSAFE (R MAIN GEAR) LIGHT WAS ON. LIGHT REMAINED ON DURING GEAR UPLATCH CHK. THE R MAIN GEAR REMAINED DOWN AND LOCKED. THE GEAR WAS CYCLED TWICE BUT WITHOUT A CHANGE IN THE CONDITION. ACFT SPD WAS MAINTAINED WITHIN GEAR DOWN SPD LIMITATIONS. AFTER CYCLING THE GEAR; THE PIC REQUESTED THE FE TO CHK FOR GEAR PINS ON BOARD. ONLY 1 FOUND ON BOARD. WE CONTACTED COMPANY AND RETURNED TO DEP ARPT (DAL) WITHOUT INCIDENT. UPON BLOCK-IN; R MAIN GEAR HAD PIN INSTALLED WITH NO RED STREAMER ATTACHED. UPON INSPECTION OF 1 GEAR PIN ON BOARD; FOUND RED STREAMER ATTACHED WITH .032 SAFETY WIRE. FLAGS ARE SUPPOSED TO BE ATTACHED WITH BRAIDED ACFT CABLE SIZE AROUND 3/32 INCHES. INSPECTED ACFT FOR DAMAGE -- NONE NOTED. CHKED BRAKES FOR TEMP; ALL WITHIN QUICK TURNAROUND PARAMETERS. DEPARTED FOR DEST ILN; ALL UNEVENTFUL. ON BLOCK IN AT DAL AFTER INCIDENT; CAPT TALKED WITH MECHS AND THEY SAID THAT THEY DID NOT PULL THE PINS ON THE PREDEP CHK. THE FE STATED THAT HE SAW NO RED FLAGS IN THE AREA OF THE MAIN GEARS DURING HIS REQUIRED SAFETY CHK OR PREDEP INSPECTION. THE MECH (ON LOAN FROM DOMICILE -- ILN) SAID THAT PULLING THE PINS ARE NOT ON HIS PREDEP CHK. WE DO NOT KNOW THIS TO BE A FACT. REGARDLESS; SOMEWHERE THE SYS BROKE DOWN BECAUSE 3 SEPARATE CHKS WERE DONE AND NO ONE FOUND THE INSTALLED GEAR PINS (IT IS ASSUMED THAT THE L GEAR PIN CAME OUT AERODYNAMICALLY ON TKOF; OR IT WAS SHEARED OFF ON GEAR RETRACTION). SOLUTION: IF PULLING THE GEAR PINS ARE NOT A PART OF THE MAINT PREDEP CHKLIST; IT SHOULD BE ADDED. ALSO; A COMPANY FLC LETTER (MEANS OF IMMEDIATE NOTIFICATION) SHOULD BE PUT OUT ADDRESSING THE POSSIBILITY OF A PIN(S) INSTALLED WITH THE RED STREAMER MISSING. FINALLY; GREATER ATTN SHOULD BE EXERCISED IN CLOSE INSPECTION OF THE GEAR PIN RECEPTACLE FOR PIN(S) INSTALLED DURING EACH RESPONSIBLE CREW MEMBER'S PREFLT INSPECTION.