What was found
THE FORWARD MUFFLER WAS REMOVED FROM THE NR 1 AND NR 2 CYLINDERS. THE INTERIOR SURFACES OF THE LT AND RT RISERS REVEALED WHITE AND GRAY DEPOSITS CONSISTENT WITH NORMAL OPERATION. A VISUAL INSPECTION REVEALED THE MUFFLER BAFFLING HAD SEPARATED FROM ITS LT SIDE ATTACHMENT COVERING THE EXHAUST PORT. WHEN A FLASHLIGHT WAS SHINED IN THE EXHAUST PORTION OF THE MUFFLES, A RESTRICTION WAS OBSERVED AS A RESULT OF A BAFFLING FAILURE. THE DEGREE OF RESTRICTION WAS ESTIMATED AT 50 PERCENT. A SIMILAR CONDITION WAS FOUND IN THE AFT MUFFLER; HOWEVER, THE DEGREE OF RESTRICTION WAS ESTIMATED AT 90 PERCENT. THE FRONT MUFFLER, PN 66894-00, TIME IN SERVICE COULD NOT BE DETERMINED, THE AFT MUFFLER, PN 66894-02 TIME IN SERVICE WAS 1359 HOURS. THE ACFT WAS INSPECTED IAW THE REQUIREMENTS OF AN ANNUAL INSPECTION ON 05/16/2014, AT AN ACFT TOTAL TIME OF 4016 HOURS. DURING AN ANNUAL INSPECTION, AN EXTERIOR INSPECTION OF THE MUFFLER SYSTEM WAS PERFORMED; HOWEVER, THE EXHAUST SYSTEM INSPECTION RECOMMENDED BY MFG WAS NOT PERFORMED.