As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING A SCHEDULED INSPECTION, PERFORMED A PRODUCT IMPROVEMENT. REPLACEMENT OF DUCT ASSY 6914070-67. NOTICED THAT THE HEAT EXCHANGER SIDE PLATE HAD TWO CRACKS ABOUT .30 INCHES LONG. OPPOSITE SIDE OF THE HEAT EXCHANGER WAS CRACKED IN NONE OF THE FOUR CORNERS. A NEW HEAT EXCHANGER WAS INSTALLED. PERFORMED A LEAK CHECK ON THE DEFECTIVE UNIT AND FOUND THE CRACKS EXTENDED INTO THE COOLING FIN AREA, WHERE THEY CAN NOT BE SEEN.