The LEAP fuel nozzle is a highly engineered component used across the CFM International LEAP engine family. It is responsible for delivering precisely metered fuel into the combustor, where fuel atomization and distribution directly influence combustion stability, emissions performance, and engine efficiency. Since the LEAP engine entered widespread commercial service, the fuel nozzle’s design, manufacturing approach, and in service history have made it a closely monitored component for operators and maintenance providers.
Fuel Nozzle Design and Manufacturing
CFM’s LEAP fuel nozzles are produced using additive manufacturing, a process that enables complex internal geometries to be built as a single integrated component. GE Aerospace began serial production of additively manufactured LEAP fuel nozzle assemblies at its Auburn, Alabama facility in 2015, marking one of the earliest large scale applications of additive manufacturing in commercial aircraft engines.
By 2021, the Auburn facility had shipped its 100,000th additively manufactured LEAP fuel nozzle, reflecting the scale at which this manufacturing approach has been adopted within the LEAP program. Additive manufacturing allows precise control over internal fuel passages and reduces the number of individual parts compared with traditional manufacturing methods. This consistency supports predictable fuel flow and stable combustion across a wide operating range.
Above is an image of a CFM Leap Nozzle Injector with the ports in view. Photo from the GE Aerospace video about the fuel nozzle. Fair use provision.
Carbon Buildup and Service
As LEAP engines accumulated flight hours in early service, operators reported carbon buildup, commonly referred to as fuel nozzle coking, under certain operating conditions. The condition was linked to post shutdown thermal conditions in the combustor region, where residual heat contributed to carbon formation on the fuel nozzles. CFM later addressed this issue through the introduction of the Reverse Bleed System, which circulates cooling air through the engine core after shutdown to reduce carbon buildup on the fuel nozzles, according to CFM.
The Federal Aviation Administration (FAA) addressed this condition through an Airworthiness Directive (AD) issued in January 2020 covering certain LEAP-1A engines. The AD identifies fuel nozzle coking as an unsafe condition and requires operators to replace the complete set of fuel nozzles at specified intervals using parts eligible for installation under approved maintenance documentation. The directive was issued as an interim measure while long term durability improvements were under development.
Above is an image of a CFM LEAP Engine Fuel Nozzle or Injector being tested by GE. Photo from the GE Aerospace video about the engine fuel injector. Modified by FlyRadius. Fair use provision.
The Reverse Bleed System
Rather than redesigning the fuel nozzle hardware itself, CFM and GE Aerospace pursued a system level mitigation to address the thermal environment associated with carbon formation. This joint effort resulted in the introduction of the Reverse Bleed System (RBS).
The RBS modifies airflow management after engine shutdown by routing cooling air through the engine core, lowering temperatures in the combustor and fuel nozzle region. By reducing post shutdown heat soak, the system is intended to limit the conditions under which carbon deposits can form within the fuel nozzle.
The RBS was certified by both the FAA and the European Union Aviation Safety Agency in 2023 for LEAP-1A engines. In early 2024, CFM began delivering new production LEAP-1A engines equipped with the system to Airbus. According to CFM, the RBS is intended to reduce the frequency of on-wing fuel nozzle replacements and better align fuel nozzle maintenance with scheduled engine shop visits rather than unscheduled removals.
Fuel Nozzle Part Numbers
For maintenance planning and parts sourcing, the primary CFM LEAP fuel nozzle part numbers commonly referenced are 2085M31G03 and 2085M31G05, which are GE Aerospace/CFM designated part numbers corresponding to complete fuel nozzle assemblies as listed in LEAP engine maintenance and parts catalogs.
In addition to the CFM designated numbers, 6120066E03 and 6120066E05 appear in parts databases and industry catalog searches as Parker Aerospace assigned OEM part numbers associated with LEAP fuel nozzle assemblies. These Parker designated part numbers are commonly encountered during part searches and sourcing activities. As with any critical engine component, operators and maintenance organizations must verify installation eligibility and configuration approval against applicable Component Maintenance Manuals, service bulletins, and regulatory requirements before procurement or installation.
A Look Back on Durability
Fuel nozzle coking was one of several early durability issues identified as the LEAP engine family entered high utilization service. In addition to the RBS fuel nozzle mitigation, CFM and GE Aerospace pursued other durability improvements affecting engine components such as high pressure turbine hardware. These efforts reflect the normal service maturation process of a new generation engine operating at higher temperatures and pressures than previous designs.
Above: a photo of the CFM LEAP Engine Fuel Injector or Nozzle from the side. Photo from the GE Aerospace video about the engine fuel injector. Modified by FlyRadius. Fair use provision.
Overview and Current Status
Early in service durability concerns related to fuel nozzle coking led to regulatory action and the introduction of the Reverse Bleed System, which addresses the thermal conditions associated with carbon formation without altering the fuel nozzle design. Key LEAP fuel nozzle part numbers include 2085M31G03 and 2085M31G05, with 6120066E03 and 6120066E05 recognized as Parker Aerospace assigned part numbers.
