As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
HEATER CORE RECEIVED FROM CUSTOMER. UPON TEARDOWN, FOUND INTERIOR OF THE COMBUSTION HEAD SEVERELY WORN FROM FLAME EROSION. PREVIOUS INSPECTIONS BY THIS REPAIR STATION HAVE FOUND SMALL HOLES APPEARING IN THE WALL OF THE COMBUSTION HEAD. FROM THE OUTSIDE, THE COMBUSION HEAD APPEARS GOOD INTERNALLY, THIS COMBUSTION HEAD IS UNAIRWORTHY. BY FOLLOWING THE MFG AND MM THESE CONDITIONS WOULD HAVE BEEN FOUND EARLIER. TBO TIME IS EVERY 500 HOURS OF HEATER OPERATION OR EVERY ENGINE OVERHAUL, WHICHEVER OCCURS FIRST. (K)