What was found
THE FLIGHT CREW INDICATED THEY SAW AND SMELLED SMOKE IN THE CABIN AREA WITH LIGHTS ON DIM WHILE AT CRUISE. LIGHTS WERE TURNED OFF AND THE SMOKE AND ODOR DISSIPATED. THE FLIGHT WAS CONTINUED WITHOUT FURTHER PROBLEM. TROUBLESHOOTING BY MAINTENANCE FOUND THE LT OVERWING EXIT WINDOW SHADE STUCK IN THE UPWARD POSITION. WHEN IT WAS PULLED DOWN IT WAS FOUND TO BE BURNED, DISCOLORED, AND MELTED. THE SIDEWALL WAS REMOVED AND NO OTHER EVIDENCE OF BURNING WAS FOUND. IT WAS ALSO NOTED THAT THE WINDOW SHADE HAD BEEN INSTALLED UPSIDE DOWN. EXTENSIVE TROUBLESHOOTING WAS UNABLE TO FIND A CAUSE OF THE PROBLEM. ENGINEERING IS CONTINUING THE INVESTIGATION INTO THE CAUSE. THE WINDOW SHADE WAS REMOVED AND REPLACED. OPEN