As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING A SCHEDULED INSPECTION, HEAT EXCHANGER SIDE PLATE HAD A .35" LONG CRACK AND THE OPPOSITE SIDE WAS ALSO CRACKED IN ONE CORNER. PERFORMED A LEAK DOWN TEST OF THE DEFECTIVE HEAT EXCHANGER AND FOUND THAT THE CRACK EXTENDED INTO THE INTERNAL PORTION OF THE EXCHANGER IN THE COOLING FIN AREAS.