What was found
DURING POST-FLIGHT OF APU OIL, FOUND MANY SMALL SECTIONS OF SS FOIL EMBOSSED LINER LAYING ON FLOOR OF APU ENCL. REMOVED COVER ASSY & FND CLAMP ASSY THAT HOLDS SURGE VALVE EXHAUST AIR TO EXH DUCT BROKEN AT WELD ON THE CLAMP. THIS CAUSED HOT EXHAUST GASSES TO HIT DIRECTLY ON APU ENCL BOX & NOT EXHAUST OVERBOARD. THIS THEN CAUSED SS FOIL MATERIAL TO BURN OFF & ALSO PULL AWAY FROM APU ENCL STRUCTURE ON THE COMPLETE RT SIDEWALL & ONE-THIRD OF FWD RT SECTION OF THE WALL. IF THIS WAS NOT FOUND, NEXT APU START WOULD HAVE CAUSED A BURN-THROUGH OF APU ENCLOSURE & POSSIBLY OTHER STRUCTURAL DAMAGE. NOTE: ALLIED SIGNAL HAS SB ISSUED TO CORRECT PROBLEM, SB GTCP 36-49-6093. DID NOT HAVE THIS INSTALLED AT THE TIME.