What was found
MCN - MAJOR REPAIR - DURING C-16 CHECK A 1 1/2" CRACK WAS FOUND ON L/H AIR CONDITIONING BAY HEAT EXCHANGER COMPOSITE DUCT SUPPORT RETAINER AT BS 619, LBL 53. MAINTENANCE FABRICATED A DOUBLER FOR L/H AIR CONDITIONING BAY HEAT EXCHANGER COMPOSITE DUCT SUPPORT RETAINER AT BS 619, LBL 53, IAW B737-300 SRM 51-70-13, PG. 1-5, TREATED & PRIMED DOUBLER IAW B737-300 SRM 51-70-13, PG.1, FIG.1, INSTALLED DOUBLER IAW BOEING DWG 65-49573, AND B737-300 SRM 51-70-13, PG.1-5, FIG. 1.