What was found
ON TAKEOFF DUCT TEMP WENT TO OVER 110 DEG AND A STRONG ACRID BURNING SMELL AND FAINT SMOKE WAS IN COCKPIT. FLIGHT ATTENDANTS ALSO SMELLED WHAT THEY THOUGHT WAS PLASTIC BURNING IN THE BACK OF THE AIRCRAFT. RETURNED TO DEPARTURE AIRPORT / [01] PERFORMED FIM TASK 21-00-806. NO BURNING SMELL OR FAINT SMOKE APPEARED DURING TEST AND ALL CONDITIONS WERE FOUND TO BE NORMAL AT THIS TIME. AIRCRAFT IS OK FOR SERVICE.