Paul Seidenman and David J. Spanovich San Francisco

This year's Farnborough International Airshow was dominated by the headline-making announcements of huge orders for Boeing's 737 MAX, along with more modest sales for Airbus's rival A320NEO. In both cases, the major selling point is double-digit fuel savings over current models, given the cutting-edge technology incorporated into the CFM Leap family and the new geared-turbofan Pratt & Whitney PW1100G, offered as an option for the A320NEO, along with the Leap-1A.

The technology incorporated in these next-gen engines has little to no history in the airline world.

Mark Wibben, director of powerplants for Southwest Airlines, reports that, while the Leap-1B's high-temperature operation will employ more expensive materials, its maintenance cost per flight hour should be relatively flat compared to the CFM56 engines now powering its fleet. The Leap-1B will power the 737 MAX, for which Southwest was the launch customer.

“Fuel burn is our biggest concern,” Wibben notes. “But, since the Leap-1B is a new—rather than a derivative—engine, we expect that new tooling and maintenance procedures will be developed to maintain the engine on-wing, and that durability will be at least the same as our current engines.”

Bill Tiffany, Southwest's senior director of supply-chain management, reports that Boeing is advertising a 14–15% improvement in fuel burn, using the 737NG series as a baseline for comparison. Of that, 11% is attributable to the engine, with the remainder to airframe design changes. Tiffany says that the Leap-1B draws on technology that is already proving itself in service.

“Much of the material to be used in this engine is already flying on the GEnx and GE90. For example, composites are used in the GEnx fan case, fan blades and twin-annular, pre-swirl (TAPS) combustor component,” says Tiffany. “There will be improved airflow around the blades and fewer piece parts, which means that there will be less to go wrong.”

The airline is not expecting premature line-replaceable-unit removals because of the engine's high heat operation, he says. “The large fan and high bypass ratio should provide better cooling.”