As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING ROUTINE MX ON THE HYD SYS, MX DISCORVERED THAT SOME OF THE INSULATION SURROUNDING THE COCKPIT AIR DUCT MUFFLER ASSY ON THE FLOOR STRUCTURE IN THE AFT BAGGAGE AREA. INVESTIGATION REVEALED THAT THE MUFFLER WAS CRACKED IN 2 AREAS ALONG THE VERTICAL SIDE AT CORNER 3" LONG AND THE OTHER 2.5" LONG NEAR THE INLET PORT. THE CRACKS WERE REPORTED TO TECH SUPPORT. THE UNIT WAS REPLACED WITH NEW.