What was found
ON DESCENT, WITH WING ANTI ICE ON, RECEIVED LOWER AFT BODY LIGHT, WITH LOST AUTO PRESSURIZATION. RAN QRH, RESET WING ANTI ICE & TRIED AGAIN. RECEIVED LOWER AFT BODY LIGHT & AUTO PRESSURIZATION FAIL LIGHT AGAIN. RAN PRESSURIZATION IN MANUAL. TRIED AUTO PRESSURIZATION AGAIN UNDER 10,000 FT AND IT WORKED. LT WING ANTI ICE OFF REMAINDER OF FLIGHT. WOULD NOT MAINTAIN PRESSURIZATION WITH SINGLE PACK UNDER 10,000 FT. DUCT AT AFT PRESSURE BULKHEAD HAS A PIECE MISSING. INSTALLED WING ANTI ICE DUCTING IAW MM 36-00-001-2. PERFORMED LEAK CHECK IAW MM 30-13-00-5. OPS CHECKED NORMAL. PERFORMED OVERHEAT DETECTION TEST IAW MM 26-14-000-5. OPS CHECKED NORMAL.