What was found
ON TAKEOFF, BLEED AIR DID NOT GO TO LOW FLOW. AIRCRAFT BECAME VERY HOT AND STARTED TO FILL WITH SMOKE. WENT TO EMERGENCY DEPRESSURIZATION, TURNED OFF BLEED AIR AND LANDED. IT WAS REPORTED THAT THE EMERGENCY VALVES WERE OPENED TO PRESSURIZE THE AIRCRAFT IN THE HANGAR. POWER WAS SHUT OFF AT THE EXTERNAL POWER UNIT BEFORE THE BLEED AIR VALVE SWITCHES WERE PLACED IN THE OFF POSITION, CAUSING THE VALVES TO STAY OPEN AND THE WARNING LIGHT TO EXTINGUISH. THE FLIGHT CREW USED THE ABBREVIATED CHECKLIST AND PLACED THE BLEED AIR SWITCHES FROM EMERGENCY TO ON, WHICH LEFT THE EMERGENCY VALVES OPEN. (M)