What was found
RETURNED TO DEPARTURE. AT FL 240, RECEIVED AN EICAS BLEED 1 LEAK AND BLEED 1 FAIL. ACCOMPLISHED QRH AND CABIN ALTITUDE WARNING CAME ON. CABIN ALTITUDE REACHED 11500 FT. PERFORMED EMERGENCY DESCENT AND CABIN PRESSURE RETURNED TO NORMAL. OPENED BOTH AIR CONDITIONING BAY FOR INSPECTION OF 1 AND 2 PACKS AND DUCTS. FOUND NR 2 PACK WITH A BLOWN DUCT AT PACK OUTLET. R & R BLOWN DUCT IAW AMM 21-51-21. LEAK CHECK AND OPS CHECK OF 2 PACK GOOD. ALSO, ACCOMPLISHED OPS CHECK OF THE CPCS AND FOUND TO BE OK IAW TASK 21-31-00-810-808-A. TROUBLESHOT BLEED 1 LEAK MESSAGE IAW FIM 36-21-00-810 AND FOUND OVERHEAT CONDITION AT LOCATION 13.60 IN THE LT PYLON AREA. FURTHER T/S REVEALED A TORN SEAL AT THE LT/ PYLON PRE-COOLER EXHAUST OUTLET. REPAIRED LT PYLON EXHAUST OUTER SEAL IAW AMM 54-50-25, NO DEFECTS NOTED.