What was found
AIR RETURN AT 2200 MSL ON CLIMB, A CHILDS BALLOON WENT THROUGH NR 2 ENGINE. A MODERATE COMPRESSOR STALL, SMELL IN CABIN, LOSS OF .2 EPR. AIRCRAFT MADE AN UNEVENTFUL LANDING AT MDW, ENGINE IND NORMAL ON FINAL. VISUALLY INSPECTED INLET AND EXHAUST AREAS, REMOVED DEBRIS FROM INLET AREA AND CSD OIL COOLER. RAN ENGINE PER BOEING MM, OPS CHECK NORMAL.