CFM International LEAP

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Mockup of a LEAP-X
Type Turbofan
National origin France/United States
Manufacturer CFM International
First run 4 September 2013 (LEAP-1A)
13 June 2014 (LEAP-1B) [1][2]
Major applications Airbus A320neo
Boeing 737 MAX
Number built 2+
Developed from General Electric GEnx

The CFM International LEAP (formerly called LEAP-X) is a high-bypass turbofan engine. It is currently under development by CFM International, a 50-50 joint venture company between GE Aviation of the United States and Snecma of France.

Design and development[edit]

The LEAP ("Leading Edge Aviation Propulsion")[3] incorporates technologies that CFM developed as part of the LEAP56 technology acquisition program, which CFM launched in 2005.[4] The engine was officially launched as "LEAP-X" on 13 July 2008.[5] It is intended to be a successor to the CFM56-5B and CFM56-7B. The LEAP's basic architecture includes a scaled up version of SAFRAN's low pressure turbine used on the GEnX engine. The fan has flexible blades manufactured by a resin transfer molding process, which are designed to untwist as the fan's rotational speed increases. While the LEAP is designed to operate at a higher pressure than the CFM-56 (which is partly why it is more efficient), GE plans to set the operating pressure lower than the maximum in order to maximize the engine's service life and reliability. Currently proposed for the LEAP is a greater use of composite materials, a blisk fan in the compressor, a second-generation Twin Annular Pre Swirl (TAPS II) combustor, and a bypass ratio around 10-11:1. These technological advances are projected to produce 16% lower fuel consumption.[5][6][7] Reliability is also supported by use of an eductor-based oil cooling system similar to that of the GenX, featuring coolers mounted on the inner lining of the fan duct. According to Aviation Week's article, "The eductor device produces a venturi effect, which ensures a positive pressure to keep oil in the lower internal sump."[8]

In total, 28 test engines will be used by CFM to achieve engine certification, and 32 others will be used by Airbus, Boeing and COMAC for aircraft certification and test programs.[1] The first engine entering the test program successfully reached and sustained 33,000 lb. of thrust, required to satisfy the highest rating for the Airbus A321. The same engine ultimately reached 35,000 lb. of thrust in test runs.[9] General Electric carried out the first test flight, of a LEAP-1C, in Victorville, California, with the engine mounted on the company's Boeing 747 flying testbed, on October 6, 2014, The C version features a thrust reverser equipped with a one piece O-ring replacing a 2 piece door. The thrust reverser is deployed by the O-ring sliding aft, reducing the drag that was induced by the older design and improving efficiency.[10]


The LEAP engine has attracted more than 5,000 orders and GE plans to produce 1,700 engines by the end of 2018.[8] The Commercial Aircraft Corporation of China (COMAC) has chosen the LEAP engine for its new COMAC C919 aircraft.[11]

The company expects to receive certification for the first LEAP, the LEAP-1C, for China's 150-seat COMAC C919 twinjet. The aircraft is due to enter service in 2016.[12] The engine will also be deployed in the same year on the new Airbus A320neo variant.[13]

On July 20, 2011, American Airlines announced that it planned to purchase 100 Boeing 737 aircraft featuring the LEAP-1B engine.[14] The project was approved by Boeing on August 30, 2011 as the Boeing 737 MAX.[15][16] Southwest Airlines is the launch customer of the 737 MAX with a firm order of 150 aircraft.[17]



Data from CFM International

General characteristics

  • Type: Twin-spool, high bypass turbofan
  • Length:
  • Diameter: 1.75 - 1.98 m
  • Dry weight:


  • Compressor: Single-stage fan, 3-stage low pressure compressor, 10-stage high pressure compressor[7]
  • Combustors: annular
  • Turbine: Two-stage high pressure turbine, 7-stage (737 MAX: 5-stage) low pressure turbine


Fan diameter [18] 78 in (1.98 m) 69.4 in (1.76 m) 78 in (1.98 m)
Bypass ratio (BPR) [18] 11:1 9:1 11:1
Overall pressure ratio (OPR) [18] 40:1 40:1 40:1
Thrust [19] 24,500–32,900 lbf (109–146 kN) 23,000–28,000 lbf (100–120 kN) 27,980–30,000 lbf (124.5–133.4 kN)
Fuel burn (vs. current CFM56-7BE engine) [20] ~ -15% ~ -15% ~ -15%
Stage count [21] 1-3-10-2-7 1-3-10-2-5 1-3-10-2-7
Application [22] Airbus A320neo family Boeing 737 MAX family COMAC C919
Entry into service [22] 2016 2017 2018

See also[edit]

Related development
Comparable engines
Related lists


  1. ^ a b "CFM launches a new era as first LEAP engine begins ground testing". CFM International. 2013-09-06. Retrieved 2013-09-07. 
  2. ^ "CFM begins LEAP-1B engine ground test program". CFM International. 2014-06-18. Retrieved 2014-06-19. 
  3. ^ LEAP Turbofan Engine, History
  4. ^ CFM Laying the Technology Foundation for the Future. CFM International
  5. ^ a b "CFM Unveils New LEAP-X Engine". CFM International. 2008-07-13. Retrieved 2008-07-16. 
  6. ^ New engines: flurry of activity despite downturn
  7. ^ a b LEAP-X: Redefining Turbofan Engines for Narrowbody Aircraft
  8. ^ a b Norris, Guy, Pressure testing, Aviation Week and Space Technology, October 28, 2013, p. 43
  9. ^ Norris, Guy, Pressure testing, Aviation Week and Space Technology, October 28, 2013, pp.42-43
  10. ^ Norris, Guy, Boom time, Aviation Week & Space Technology, October 13, 2014, p.40
  11. ^ CFM International to provide engines for COMAC's C919
  12. ^ CFM to finish Leap core testing by mid-May
  13. ^ Airbus A320neo story FlightGlobal
  14. ^ "Boeing and American Airlines Agree on Order for up to 300 Airplanes - Jul 20, 2011". July 20, 2011. Retrieved May 31, 2013. 
  15. ^ Boeing Confirms Duopoly With Airbus Announcing Re-Engining Of 737. Forbes
  16. ^ Boeing rendering illustrates major changes to 737NE.
  17. ^ "Southwest Airlines Will Become Launch Customer for the New Boeing 737 Max Aircraft - Southwest Airlines Newsroom". December 13, 2011. Retrieved May 31, 2013. 
  18. ^ a b c "LEAP Brochure". CFM International. May 28, 2013. Retrieved May 7, 2014. 
  19. ^ "The Leap Engine". Retrieved May 31, 2013. 
  20. ^ "Aviators". September 12, 2012. Retrieved May 31, 2013. 
  21. ^ November 9, 2011 (November 9, 2011). "Comparing the new technology Narrow-body engines: GTF vs LEAP maintenance costs". Retrieved May 31, 2013. 
  22. ^ a b "CFM To Release A320NEO Leap Engine Final Design By Year-End". November 7, 2012. Retrieved May 31, 2013. 

External links[edit]