CFM International LEAP

The CFM International LEAP ("Leading Edge Aviation Propulsion") is a high-bypass turbofan engine produced by CFM International, a 50–50 joint venture between the American GE Aerospace and the French Safran Aircraft Engines. As the successor to the widely used CFM56, the LEAP competes directly with the Pratt & Whitney PW1000G to power narrow-body aircraft.

Design

The LEAP incorporates several design features intended to improve fuel efficiency and reduce emissions compared to the CFM56. Its architecture includes a scaled-down version of the low-pressure turbine used on the General Electric GEnx engine. The fan blades are made of composite materials via a resin transfer molding process and are designed to untwist under load to maintain aerodynamic efficiency.

Although capable of operating at higher pressures than the CFM56, the LEAP engine is typically operated at lower pressures to improve durability and service life. It utilizes a higher proportion of composite materials, features the second-generation Twin Annular Pre-mixing Swirler (TAPS II) combustor, and has a bypass ratio of approximately 10:1 to 11:1. The engine’s high-pressure compressor achieves a compression ratio of up to 22:1, approximately double that of its predecessor. The turbine shrouds are made using ceramic matrix composites (CMCs), which provide high temperature resistance with reduced weight. These and other design improvements are projected to result in a 16% reduction in fuel consumption relative to earlier CFM engines.

The LEAP also incorporates an eductor-based oil cooling system, derived from the GEnx design. This system includes oil coolers mounted on the fan duct lining and uses a venturi effect to maintain oil pressure within the internal sump. Additionally, the LEAP includes some of the first FAA-certified 3D-printed components used in a commercial jet engine.

The LEAP-1C variant, developed for the Chinese-built Comac C919, reportedly omits some of the advanced technologies found in other LEAP models. According to industry sources, this decision was influenced by concerns that the technology could be stolen and put into the CJ-1000A engine being developed by another state-owned manufacturer, the Aero Engine Corporation of China. Some analysts have described the LEAP-1C as more closely related in capability to an upgraded CFM56 than to other LEAP variants.

Development

The LEAP incorporates technologies that CFM developed as part of the LEAP56 technology acquisition program, which CFM launched in 2005. The engine was officially launched as ''LEAP-X'' on 13 July 2008. It is intended to be a successor to the CFM56.

In 2009, COMAC selected the LEAP engine for the C919. The aircraft was due to begin testing in 2016.
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. The first engine entering the test program reached and sustained of thrust, required to satisfy the highest rating for the Airbus A321neo. The same engine ultimately reached of thrust in test runs.

CFM 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 aircraft on 6 October 2014. The -1C version features a thrust reverser equipped with a one-piece O-ring replacing a two-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.

In April 2015, it was reported that the LEAP-1B was suffering up to a 5% shortfall on its promised reduction in fuel consumption.

It obtained its 180-minute ETOPS approval from the U.S. Federal Aviation Administration and the European Aviation Safety Agency on 19 June 2017.

Orders

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

The list price is for a LEAP-1A, and for a LEAP-1B.

CFM International offers rate-per-flight-hour support agreements (also known as "power by the hour" agreements) for the engine. For a LEAP-1A engine, costs are around per engine, per day, compared to per engine, per day for the prior-generation CFM56.

In 2016, CFM booked 1,801 orders, and the LEAP backlog stood at more than 12,200, worth more than at list price.

By July 2018, the LEAP had an eight-year backlog with 16,300 sales. At that time, more LEAPs were produced in the five years it was on sale than CFM56s in 25 years.
It is the second-most ordered jet engine behind the 44-year-old CFM56, which achieved 35,500 orders. Also, on the A320neo, where the engine competes head-to-head with the Pratt & Whitney PW1000G, the LEAP had captured a 59% market share in July 2018. By comparison, the CFM56 had a 60% share of the prior-generation A320ceo market.

In 2020, GE Aviation reported that CFM had lost 1,900 orders for LEAP engines worth ( each), reducing the backlog value to . More than 1,000 cancellations came from Boeing 737 MAX orders being canceled among the Boeing 737 MAX groundings, while the remainder came from the impact of the COVID-19 pandemic on aviation.

In May 2025, the United States Department of Commerce paused the export of LEAP engines to COMAC.

Production

In 2016, the engine was introduced in August on the Airbus A320neo with Pegasus Airlines and CFM delivered 77 LEAP. 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. CFM was to produce 1,200 engines in 2018, 1,900 in 2019, and 2,100 in 2020. This is compared to the 1,700 CFM56 produced in 2016.

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, US in addition to its previous Durham, North Carolina, US 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. Safran assembles its production in Villaroche, France, Safran and GE each assemble half of the annual volume. Mecachrome plan to produce 120,000–130,000 LEAP turbine blades in 2018 up from 50,000 in 2017.

In mid-June 2018, deliveries remained four to five weeks behind schedule, down from six, and should catch up in the fourth quarter as the quality variation of castings and forgings improves. The production has no single manufacturing choke point by selecting multiple suppliers for every critical part.

From 460 in 2017, 1,100 LEAPs should be built in 2018, along with 1,050 CFM56s, as it encountered unexpected sales, to pass the record production of 1,900 engines in 2017. It will stay at over 2,000 engines per year as 1,800 LEAPs should be produced in 2019, while CFM56 production will drop, then 2,000 in 2020. In 2018, 1,118 engines were delivered.

Over the first half of 2019, CFM revenues were up by 23% to with 1,119 engine deliveries; declining sales of CFM56 (258 sold), more than offset by LEAP (861 sold). Recurring operating income rose by 34% to , but was reduced by () due to the negative margins and initial costs of LEAP production, before a positive contribution expected in the second half. Revenues should grow by 15% in 2019 but free cash flow depends on the return to service of the grounded 737 MAX.

In 2019, LEAP production rose to 1,736 engines, and orders and commitments reached 1,968 amid the 737 MAX groundings, compared with 3,211 for 2018, for a stable backlog of 15,614 (compared to 15,620). CFM expects to produce 1,400 LEAP engines in 2020, including an average of 10 weekly LEAP-1Bs for the Boeing 737 Max. By March 2022, CFM intended to output 2,000 engines in 2023, up from 845 deliveries in 2021.
In 2023, CFM booked over 2,500 orders, resulting in a backlog of 10,675, delivered 1,570 Leap engines, up by 38% from 1,136 in 2022, and was expecting 20-25% more deliveries for 2024.

The troubled introduction of the Pratt & Whitney PW1100G on the A320neo has motivated customers to choose LEAP engines. LEAP market share rose from 55% to 60% in 2016, but orders for 1,523 aircraft (%) had not specified which engine would be chosen. From January through early August 2017, 39 PW1100G engines versus 396 CFM LEAP engines were chosen. By 2024, the LEAP was selected for 75% of the A320neo orders. As an example of PW1100G 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.

A contract for the production of components for the low-pressure turbine of the LEAP engine was signed on February 12, 2025, between Safran Aircraft Engines and India's Titan Engineering and Automation Limited. Manufacturing will start from 2026. An additional agreement was signed for manufacturing turbine forged parts with Hindustan Aeronautics Limited.

Operations

The Boeing 737 MAX LEAP-1B started revenue service in May 2017 with Malindo Air with 8 hours of daily operation, while the A320neo LEAP-1A surpassed 10 hours 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.

In early October 2017, an exhaust gas temperature shift was noticed during a flight and a CMC shroud coating in the turbine was seen flaking off in a borescope inspection, creating a leaking gap: eight in-service engines are seeing their coating replaced. Safran provisioned () to troubleshoot in-service engines, including potentially LEAP-1Bs. Forty LEAP-1A were replaced and the part should be replaced in over 500 in-service engines, while shipments are four weeks behind schedule. Deliveries with the permanent CMC environmental-barrier coating fix began in June.

On 26 March 2019, due to the Boeing 737 MAX groundings, Southwest Airlines flight 8701 ( 737 MAX 8) took off from Orlando International Airport for a ferry flight to storage without passengers, but soon after problems with one of the engines caused an emergency landing at the same airport. Southwest then inspected 12 LEAP engines, and two other airlines also inspected their engines. CFM recommended replacing the fuel nozzles more often due to coking, a carbon buildup.

Applications

File:Airbus A320neo CFM LEAP nacelle.jpg, The LEAP-1A is one of two engine options on the Airbus A320neo family.
File:Boeing 737-9 MAX CFM LEAP-1B PAS.jpg, The LEAP-1B is the exclusive engine option for the Boeing 737 MAX.
File:LEAP-1C (tight crop).png, The LEAP-1C is the exclusive engine option for the Comac C919.

Specifications

See also

Notes

References

External links

CFM LEAP page

CFM LEAP
on GE Aerospace

CFM Unveils New LEAP-X Engine





Plane makers switch to cleaner engines

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High-bypass turbofan engines
2010s turbofan engines
General Electric aircraft engines
Snecma aircraft engines