The CFM International LEAP is a high-bypass turbofan engine. It is produced by CFM International, a 50-50 joint venture company between GE Aviation of the United States and Safran Aircraft Engines (formerly known as Snecma) of France. It is a modernized complement to the successful CFM56, intended to compete with the Pratt & Whitney PW1000G in the single-aisle jetliner market. CFM intends to replace the CFM56 with the LEAP.


The LEAP's basic architecture includes a scaled-down 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 CFM56 (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-mixing Swirler (TAPS II) combustor, and a bypass ratio around 10-11:1. GE is using ceramic matrix composites (CMC) to build the turbine shrouds.[6]

These technological advances are projected to produce 16% lower fuel consumption.[7][8][9] 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."[10] The engine has some of the first FAA-approved 3D-printed components.[11][12]


side view with cutaways

The LEAP ("Leading Edge Aviation Propulsion")[13] incorporates technologies that CFM developed as part of the LEAP56 technology acquisition program, which CFM launched in 2005.[14] The engine was officially launched as LEAP-X on 13 July 2008.[7] It is intended to be a successor to the CFM56-5B and CFM56-7B.

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][15] The first engine entering the test program successfully reached and sustained 33,000 lbf (150 kN) of thrust, required to satisfy the highest rating for the Airbus A321neo. The same engine ultimately reached 35,000 lbf (160 kN) of thrust in test runs.[16]

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 -1C 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.[17] In April 2015, it was reported that the LEAP-1B was suffering up to a 5% shortfall on its promised reduction in fuel consumption.[18] It obtained its 180 minute ETOPS approval from the U.S. Federal Aviation Authority and the European Aviation Safety Agency on June 19, 2017.[19]


The Commercial Aircraft Corporation of China (COMAC) has chosen the LEAP engine for its new COMAC C919 aircraft.[20] The aircraft was due to begin testing in 2016.[21]

On July 20, 2011, American Airlines announced that it planned to purchase 100 Boeing 737 aircraft featuring the LEAP-1B engine.[22] The project was approved by Boeing on August 30, 2011 as the Boeing 737 MAX.[23][24] Southwest Airlines is the launch customer of the 737 MAX with a firm order of 150 aircraft.[25]

CFM International offers its support for the engine, and signed a 15-year Rate per Flight Hour agreement with Loong Air for 20 LEAP-1A at U.S $333 million, or $3039 per engine per day, in contrast with U.S. $138 million for 17 CFM International CFM56 over 12 years or $1852 per engine per day.[26] As a number of A320neo engine for ANA group of Japan was also ordered in 2014, there is a possibility to select the LEAP engine.[27]

In 2016 CFM booked 1,801 orders, LEAP backlog is at more than 12,200 for more than $170 billion U.S. at list price.[28] In early 2018, the backlog was at 14,500, with a 59% share of the A320neo market for decided customers as it has an 18 percentage point advantage in utilization rate over the GTF.[29]


In 2016, the engine was introduced in August on the Airbus A320neo with Pegasus Airlines and CFM delivered 77 LEAP.[28] With the 737 MAX introduction, CFM delivered 257 Leaps in the first three quarters of 2017, including 110 in the third: 49 to Airbus and 61 to Boeing, and targets 450 in the year.[30] CFM should produce 1,200 engines in 2018, 1,900 in 2019, and 2,100 in 2020.[31] This is compared to the 1,700 CFM56 produced in 2016.[32]

To cope with the demand, CFM is duplicating supply sources on 80% of parts and even subdivide assembly sites, already shared between GE and Safran. GE assembles its production in Lafayette, Indiana, in addition to its previous Durham, North Carolina, facility. As more than 75% of the engine comes from suppliers, critical parts suppliers pass “run-rate stress tests” lasting two to 12 weeks. Pratt & Whitney acknowledges a production ramp-up bottleneck on its rival PW1100G geared turbofan including a critical shortage of the unique aluminium-titanium fan blade, hitting the Airbus A320neo and the Bombardier CSeries deliveries.[33] Safran assembles its production in Villaroche, France, Safran and GE each assemble half of the annual volume.[34]. Mecachrome plan to produce 120,000-130,000 Leap turbine blades in 2018 up from 50,000 in 2017.[35]


The troubled introduction of the PW1100G is motivating customers to choose LEAP engines to power their A320neo aircraft; 39 vs 396 units from January through early August 2017. As an example of PW110G reliability issues, 9% of LEAP-powered A320neos were out of service for at least one week in July 2017, compared with 46% of those using the PW1100G. LEAP market share rose from 55% to 60% in 2016, but orders for 1,523 aircraft (29%) still haven't specified which engine will be chosen.[36]

Introduction is smooth with the Boeing 737 MAX Leap 1B starting revenue service in May 2017 with Malindo Air with 8 h daily utilization, while the A320neo Leap 1A surpassed 10 h per day by July; Safran discovered a production quality defect on Leap 1B low-pressure turbine disks during assembly for possibly 30 engines and CFM is working to minimize flight-test and customer-delivery disruptions.[37]

In early October 2017, an exhaust gas temperature shift was noticed during a flight and a CMC shroud coating in the HP turbine was seen flaking off in a borescope inspection, creating a leaking gap: eight in-service engines are seeing their coating replaced.[38] Safran provisioned €50 million ($58 million) to trouble-shoot in-service engines, including potentially Leap-1Bs.[30] Forty Leap-1A were replaced and the part should be replaced in over 500 in-service engines, while shipments are four weeks behind schedule.[39]


Airbus A320neo prototype with LEAP-1A engines.
CFM international Leap Engine[40]
Model Application Thrust range Introduction
1A Airbus A320neo family 24,500–35,000 lbf (109–156 kN) 2 Aug 2016[41]
1B Boeing 737 MAX 23,000–28,000 lbf (100–120 kN) 22 May 2017[42]
1C COMAC C919 27,980–30,000 lbf (124.5–133.4 kN) 2021[43]


18 blades fan
The LEAP Family
Model LEAP-1A[44] LEAP-1B[45] LEAP-1C[44]
Configuration Twin-spool, high bypass turbofan
Compressor 1 fan, 3-stage LP, 22:1 10-stage HP[46]
Combustor second generation Twin-Annular, Pre-Mixing Swirler Combustor (TAPS II)[40]
Turbine 2-stage HP, 7-stage (-1B: 5-stage) LP[47]
OPR 40:1[46] (50:1, Top-of-Climb)
TSFC ~ -15% (vs. current CFM56 engine)[40] (~0.42 lb/lbf/h (12 g/kN/s)[48])
Fan diameter[46] 78 in (198 cm) 69.4 in (176 cm) 77 in (196 cm)[49]
Bypass ratio[46] 11:1 9:1 11:1
Length 3.328 m (131.0 in) [a] 3.147 m (123.9 in) 4.505 m (177.4 in) [b]
Max. Width 2.533–2.543 m (99.7–100.1 in) 2.421 m (95.3 in) 2.659 m (104.7 in)
Max. Height 2.368–2.362 m (93.2–93.0 in) 2.256 m (88.8 in) 2.714 m (106.9 in)
Weight 2,990–3,153 kg (6,592–6,951 lb) (Wet) 2,780 kg (6,130 lb) (Dry) 3,929–3,935 kg (8,662–8,675 lb) (Wet)
Max. Take-Off 143.05 kN (32,160 lbf) 130.41 kN (29,320 lbf) 137.14 kN (30,830 lbf)
Max. Continuous 140.96 kN (31,690 lbf) 127.62 kN (28,690 lbf) 133.22 kN (29,950 lbf)
Max. rpm LP : 3894, HP : 19391 LP : 4586, HP : 20171 LP : 3894, HP : 19391
Thrust ratings[44][45]
Variant Take-Off Thrust Max. Continuous
-1A23 106.80 kN (24,010 lbf) 104.58 kN (23,510 lbf)
-1A24 106.80 kN (24,010 lbf) 106.76 kN (24,000 lbf)
-1B25 119.15 kN (26,790 lbf) 115.47 kN (25,960 lbf)
-1A26 120.64 kN (27,120 lbf) 118.68 kN (26,680 lbf)
-1B27 124.71 kN (28,040 lbf) 121.31 kN (27,270 lbf)
-1B28 130.41 kN (29,320 lbf) 127.62 kN (28,690 lbf)
-1C28 129.98 kN (29,220 lbf) 127.93 kN (28,760 lbf)
-1C30 137.14 kN (30,830 lbf) 133.22 kN (29,950 lbf)
-1A30, 32, 33, 35 143.05 kN (32,160 lbf) 140.96 kN (31,690 lbf)
  1. ^ fan case forward flange to turbine rear frame aft flange
  2. ^ fan cowl hinge beam front to centre vent tube end

See also

Related development
Comparable engines
Related lists


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External links