The CFM International LEAP is a turbofan family developed for a new generation of single-aisle airliners. Its three branches power the Airbus A320neo family, Boeing 737 MAX and COMAC C919. The aircraft-specific designations are LEAP-1A, LEAP-1B and LEAP-1C respectively; each represents a distinct installation within the common programme.[1]
Introduction and development
The first LEAP engines entered commercial service in August 2016. CFM describes the programme as a successor to the CFM56 generation, with reduced fuel consumption, lower carbon-dioxide emissions and lower noise among its objectives. These aims concern the efficiency of the complete engine and its integration with the aircraft, rather than a single isolated component.[2]
GE's retrospective of the programme describes the development of the different aircraft applications and their flight-test milestones. In particular, the LEAP-1A/-1C flight-test programme began in October 2014. The family therefore advanced through overlapping development and certification efforts, rather than having all three versions enter airline service simultaneously.[3]
Aircraft-specific configurations
CFM lists a 78-inch fan for the LEAP-1A and LEAP-1C, compared with 69 inches for the LEAP-1B. Its product summary gives maximum take-off thrust figures of approximately 33,000 lbf for the LEAP-1A, 31,000 lbf for the LEAP-1C and 28,000 lbf for the LEAP-1B. Those are manufacturer family summaries, not a claim that every certified submodel has that exact rating.[1]
The -1A competes for installations on the A320neo family, while the -1B is the sole engine for the 737 MAX. The -1C is supplied as an integrated propulsion system for the C919. These commercial and installation differences matter when comparing engines: family membership does not make the three versions interchangeable.[1]
Technology
The programme combines woven composite fan technology, ceramic-matrix composite components and additive manufacturing. Each addresses a different engineering problem, including weight, temperature capability and the manufacture of complex parts. The LEAP's development history places these materials and processes within a broader engine programme that also had to demonstrate operability and durability before entering service.[3]
Fuel and emissions
CFM's performance page states a 15 percent fuel-consumption and carbon-dioxide reduction relative to CFM56 engines. That is a comparative manufacturer claim with an identified predecessor, rather than a guaranteed reduction for every route. Aircraft size, payload, mission length and operating conditions still determine the fuel used on an individual flight.[2]