CFM launches Leap-1B ground testing for 737 Max

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CFM International has launched ground testing of the Leap-1B engine that will power the Boeing 737 Max, which is scheduled to enter service in three years.

“The start of testing on the Leap-1B engine for the 737 Max demonstrates that we are on track” to deliver the new aircraft in 2017, says Boeing vice-president and general manager of the 737 Max programme Keith Leverkuhn.

The Leap-1B is the second major version of the engine family to enter ground testing. The Leap-1A that will power the Airbus A320neo entered ground testing last September. The Comac C919 will use the Leap-1C, which uses the same turbomachinery as the Leap-1A.

“Now that we are running at full power, we can really see what it is capable of,” Cédric Goubet, CFM’s executive vice-president, says in a statement.

Among the design changes selected for the 737 Max, the Leap-1B is the single-largest contributor to Boeing’s claim that the new aircraft will be 14% more efficient than the 737NG family.

Compared to the 737NG’s CFM56-7B engine, the 1.8m (69.4in) fan diameter of the Leap-1B helps to increase the fuel efficiency by increasing bypass ratio by 50%.

Several internal changes, including a blisk fan in the compressor and a second stage in the high-pressure turbine, also allows a roughly 25% improvement in the overall pressure ratio.

CFM also is integrating a more efficient twin annular pre-swirl (TAPS II) combustor, which also is designed to significantly reduce harmful nitrous oxide (NOx) emissions.