What was found
PARTIAL LOSS OF POWER ON DEPARTURE AT 1,000` AGL. AFTER RETURNING TO LAND, ENGINE ROUGHNESS INCREASED. DURING TAXI IN, MAX ATTAINABLE RPM WAS 900. MECHANIC TROUBLESHOT AND DETERMINED THE PROBLEM TO BE FUEL STARVATION. FUEL SUPLY TO THE CARBURETOR WAS NORMAL AND ALL ENG CONTROLS FUNCTIONED NORMAL, PROMPTING THE DISASSEMBLY OF THE CARBURETOR. INTERMAL INSP REVEALED AN ANSWER. THE BOSS IN THE BOTTOM OF THE CARBURETOR WHICH RECEIVES THE MIXTURE SHAFT HAD ROTATED COUNTER-CLOCKWISE IN THE HSG. THIS PRODUCED THE SAME EFFECT AS PULLING THE MIXTURE CONTROL KNOB. LUCKILY, WAS CLOSE TO AN AIRPORT AND ABLE TO MAKE AN EMERGENCY RETURN.