What was found
WITH LANDING GEAR IN UP POSITION GEAR DOOR LIGHT WOULD REMAIN ILLUMINATED. WHILE AC WAS BEING RETURNED. A LOW-PASS WAS FLOWN PAST TOWER AND CONFIRMED SOMETHING WAS HANGING DOWN FROM AC. TOWER DECLARED AN EMERGENCY, CREW PERFORMED A MANUAL LANDING GEAR EXTENSION IN AN UNSUCESSFUL ATTEMPT TO GET GEAR DOOR TO CLOSE. A SOFT LANDING WAS MADE. IB LT MAIN GEAR DOOR WAS CONFIRMED TO BE HANGING DOWN. HEAVY ACCUMULATION OF ICE ON IB LT MAIN GEAR DOOR AND LT GEAR DOOR UPLOCK ROLLER. UPLOCK HOOK AND SWITCH WERE FOUND TO BE OUT OF ADJUSTMENT. UPLOCK HOOK AND SWITCH WERE ADJUSTED, AND LT MLG DOOR WAS REPLACED. OPS AND LEAK CHECKS WERE GOOD. AC RETURNED TO SERVICE.