ACR SMT UNABLE RETRACT LEFT MAIN GEAR AFTER TKOF. ALSO UNABLE EXTEND IT FULLY FOR LNDG AND ON LNDG ROLLOUT IT COLLAPSED CAUSING WING AND PROPELLER DAMAGE.

Narrative

ON TKOF GEAR WAS RAISED. WE HAD AN UNSAFE GEAR UP INDICATION (FLASHING RED ON HANDLE). RETURNED TO THE ARPT; ATTEMPTED NORMAL GEAR DOWN AFTER CHKING ALL CB'S AND FLT MANUAL PROCS. WE HAD NOSE WHEEL SAFE; RIGHT GEAR SAFE; LEFT GEAR; NO GREEN LIGHT AND UNSAFE FLASHING GEAR HANDLE. WE HAD CALLED AND HAD ALL THE ARPT PERSONNEL AVAILABLE; HEAD MECHANIC AND ASS'T. THEY RECOMMENDED RAISING THE GEAR AND PUMPING IT DOWN. WE HAD THE SAME SITUATION. SINCE THE LEFT GEAR WAS LOCKED HALF DOWN; EVERYONE DECIDED IT WOULD BE BETTER TO ATTEMPT A GEAR DOWN LNDG. ON LNDG; THE LEFT GEAR COLLAPSED AT 40+ KTS. SUPPLEMENTAL INFORMATION FROM ACN 81242: NO INJURIES. LEFT PROP AND WING DAMAGED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: AFTER THE LNDG THE PLT WHO IS ALSO AN A&P MECHANIC STAYED AROUND WHILE MECHANICS INSPECTED ACFT. UPON OPENING COVER PLATE OVER TOP OF TORQUE SCREW THAT OPERATES THE LNDG GEAR THEY FOUND THAT A STAINLESS STEEL CLAMP ON AN AIR DUCT IN THE SAME AREA HAD WORKED AROUND UNTIL IT WAS AGAINST THE TORQUE SCREW AND THEN EVERY TIME THE LNDG WAS ACTIVATED; IT HAD ACTED LIKE A CUTTING LATHE ON THE TORQUE SCREW UNTIL IT HAD WEAKENED IT ENOUGH SO THAT WHEN THE 2400 RPM ELECTRICAL MOTOR HIT THE JACK SCREW; IT SHEARED. RPTR ALSO RPTED FAA INVESTIGATED THE OCCURRENCE AND CLASSIFIED IT AN INCIDENT. THE FAA ALSO PUT OUT A LETTER TO ALL OPERATORS OF THIS MODEL ACFT TO INSPECT THIS STAINLESS STEEL CLAMP FOR CORRECT SIZE AND CLRNC.