Boeing has confirmed the planned fan diameter of the CFM Leap 1B engine for its 737MAX family will be 68 inches as it homes in on final definition of the advanced derivative.
Boeing Commercial Airplanes President and Chief Executive Officer Jim Albaugh says the decision represents a 'sweet spot' and provides a sufficiently high bypass ratio without excessive drag. "I think we made the right decision for us," he adds. This size is thought to be the largest possible diameter fan that can be accomodated beneath the wing without extensive modifications to the landing gear. It will, however, require the nose leg to be extended by several inches. Although Boeing has tested an A330F-like chin blister in the wind tunnel, they will likely include the additional gear leg size by internal re-arrangement of the electronics bay.
MAX is now defined with 68-inch diameter fan. (Boeing)
Speaking at the Goldman Sachs Global Industrials Conference in Boston on Nov 3, Albaugh says he is also "challenging" the development team to get the new derivative into service in advance of the 2017 target currently on the table. Albaugh also adds that commitments have now climbed to "north of 600."