As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
HEATER COMBUSTION TUBE CRACKED SEVERELY IN MULTIPLE LOCATIONS WHICH LIKELY INDICATES THAT CRACKS HAVE EXISTED FOR SOME TIME.BIG PROBLEM IS THAT THERE IS NO REQUIRED PRESSURE DECAY TEST FOR THESE HEATERS. PRESSURE DECAY TESTING SUCH AS REQUIRED FOR OTHER HEATER MODELS IAW AD 96-20-07 IS PROBABLY MOST EFFICIENT METHOD OF DETERMINING CONDITION OF COMBUSTION TUBE.