What was found
ABL - FLT 1521 - ON TAKEOFF, THE ENGINE BEGAN LOOSING POWER AND DEVELOPED A NOTICEABLE VIBRATION. THE CYLINDER HEAD TEMPERATURE AND EXHAUST GAS TEMPERATURE BEGAN TO CLIMB SO THE PILOT REDUCED POWER AND RETURNED TO THE AIRPORT WHERE AN UNEVENTFUL LANDING WAS MADE. MAINTENANCE FOUND THE RT FLAME CONE IN THE EXHAUST MUFFLER HAD COME LOOSE AND WAS BLOCKING THE EXHAUST OUTLET. THE MUFFLER WAS REMOVED AND REPLACED AND THE AIRCRAFT WAS RETURNED TO SERVICE. (X)