What was found
(CAN) HEAT EXCHANGER ASSEMBLY, C6SF1515-3 HAS HAD ALL 48 PLUG WELDS GROUND FLUSH TO THE PARENT METAL AND POLISHED. GRINDING OF THE WELDS IS NOT ALLOWED IAW THE DWG REQUIREMENTS. HEAT EXCHANGER ASSEMBLIES INSTALLED ON THE FOLLOWING ACFT S/N`S ARE AFFECTED: 869, 870, 871, 878, 881, 882, 888, 889, 895, 896, 897. MFG IS INVESTIGATING.