The world of commercial aviation propulsion is in the midst of change, upheaval and dramatic new developments. Aviation Week’s senior editor Guy Norris recently visited General Electric, Pratt & Whitney and Rolls-Royce to see first-hand the production ramp ups and developments of new turbofans about to enter service. Listen in as he discusses his behind-the-scenes visit. Read the special report on propulsion in this week's edition of Aviation Week & Space Technology.