As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING A SCHEDULED INSPECTION WE WERE PREFORMING A PRODUCT IMPROVEMENT (REPLACEMENT OF DUCT ASSY 6914070-67) WE NOTICED THAT THE HEAT EXCHANGER SIDE PLATE HAD 2 CRACKS ABOUT .30" LONG. THE OPPOSITE SIDE OF THE HEAT EXCHANGER WAS CRACKED IN 2 OF THE 4 CORNERS. A NEW HEAT EXCHANGER WAS INSTALLED. WE PREFORMED A LEAK CHECK ON THE DEFECTIVE UNIT AND FOUND THE CRACKS EXTENDED INTO THE COOLING FIN AREA, WHERE THEY CAN NOT BE SEEN.