As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED LOW AIRFLOW TO THE COCKPIT. INSPECTION FOUND INSULATION MATERIAL BLOWN FROM THE COCKPIT ESC MUFFLER. VISUAL INSP OF THE MUFFLER REVEALED 3.5 INCH CRACK AT THE LOWER WELD SEAM. THE DEFECT WAS REPORTED TO FIELD SERVICE AND THE MUFFLER WAS REPLACED WITH A NEW UNIT.