A B767-300 WAS DISPATCHED WITH A LAVATORY BLOWER EXHAUST DUCT OUTLET ON THE AFT FUSELAGE SKIN DEFERRED. LATER INSPECTION FOUND SKIN CORRODED AND OUT OF LIMITS PER STRUCTURAL REPAIR LIMITS.

Narrative

DURING THE TRANSIT; A LAVATORY BLOWER EXHAUST DUCT AREA ON THE AFT FUSELAGE WAS FOUND TO CONTAIN DISCOLORED PAINT. THE AREA WAS SUBSEQUENTLY INSPECTED AND FOUND THAT THE AREA WAS NOT JUST A PAINT FAULT BUT WAS IN FACT SOMEWHAT DEEPER AND APPEARED TO BE DELAMINATION OF A COMPOSITE MATERIAL AROUND THE DUCT OUTLET. THE AREA WAS PROTECTED WITH ALUMINUM TAPE AND A CARRIED-FORWARD ITEM MADE; PER COMPANY MAINT PRACTICES; FOR A PERIOD OF TIME WITH PERIODIC RECHKS UNTIL THE PERMANENT REPAIR WAS ACCOMPLISHED. THE AREA WAS IN FACT INSPECTED A NUMBER OF TIMES BTWN DISCOVERY AND PRESENT DATE. THE ACFT WAS ON A THROUGH-TRIP. WHEN THE TAPE WAS SEEN TO BE PEELING OFF ON SUBSEQUENT REINSPECTION; THE INDIVIDUAL THERE REALIZED THE AREA WAS IN FACT NOT COMPOSITE BUT A METAL DUCT AND SOME OF THE SKIN HAD IN FACT CORRODED AROUND THE EDGE OF THE DUCT. THE SUBSEQUENT FLT WAS CANCELED WHILST THE AREA OF CORROSION WAS EVALUATED AND PERMANENTLY REPAIRED OR THE ACFT FERRY TO A LARGER REPAIR ORGANIZATION AFTER AN INTERIM REPAIR WAS ACCOMPLISHED. MY INVOLVEMENT IN THIS ISSUE WAS AS A MAINT CTLR FOR COMPANY WHEN THE CONTRACT ACFT MAINT TECHNICIAN OF THE HANDLING AGENT TELEPHONED AND RPTED THE POSSIBLE COMPOSITE MATERIAL DELAMINATION. I GAVE HIM THE REF FOR AN INTERIM REPAIR TO COMPOSITE STRUCTURE; WHICH IN FACT IT WAS NOT. THE ITEM WAS RECOGNIZED AND DEALT WITH BY COMPANY'S MAINT TECHNICIAN ONCE IT WAS RECOGNIZED AS A METALLIC SKIN SURFACE ISSUE. MY LACK OF FOLLOW-UP RESEARCH ALLOWED THE SITUATION TO CONTINUE UNTIL OUR TECHNICIANS DISCOVERED THE CORRECT SITUATION AND PROCEEDED TO RESOLVE THE ISSUE.