As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
REPLACED MUFFLERS ON AC DUE TO THE DETERIORATED CONDITION OF THE SPARK ARRESTERS INSIDE OF THE MUFFLERS. THE SPARK ARRESTER IN THE LT MUFFLER WAS GONE. IT HAD COME LOOSE AND FALLEN OUT OF THE MUFFLER SOMEWHERE. THE SPARK ARRESTER IN THE RT MUFFLER HAD MELTED AND BOWED TO THE LT (IB). RECOMMEND MANDATORY REPLACEMENT AT A SPECIFIED TIME OR REDESIGN OF ARRESTERS.