The Federal Aviation Administration has certificated high-pressure turbine and fuel nozzle durability improvements for the CFM International LEAP-1B, the engine that powers Boeing's 737 MAX. CFM announced the approval on 18 July, putting the manufacturer on track to begin delivering updated LEAP-1B engines in 2027.
The changes address a problem that has shaped narrowbody maintenance economics for several years: LEAP engines have been coming off wing for overhaul sooner than operators expected, particularly in hot and dusty environments where fine airborne particulate accelerates wear on hot-section hardware.
What the kit changes
The high-pressure turbine durability kit brings in revised hot-section hardware, including new turbine blades, nozzles and forward inner nozzle supports. CFM has secured both engine-level and aircraft-level approvals for the changes.
"The system will double time-on-wing in hot and harsh environments like in the Middle East and India," CFM said. "CFM is beginning to industrialise production of the hardware, with full production cutover expected in early 2027."
Alongside the turbine work, the FAA has granted engine-level certification for a new LEAP-1B reverse bleed system, a cooling arrangement intended to improve fuel nozzle longevity and reduce the need for on-wing nozzle replacements. CFM is now working with Boeing to secure the aircraft-level certification that the reverse bleed system still requires, aiming to complete that before the end of the year, according to GE Aerospace vice-president of commercial programmes Tom Levin.
Taken together, CFM has said the high-pressure turbine kit and the reverse bleed system address around 80% of the durability issues the engine family has encountered.
Following the LEAP-1A
The LEAP-1B is catching up rather than breaking new ground. CFM already rolled out comparable modifications for the LEAP-1A, the variant powering Airbus A320neo family jets, and had secured regulatory approval for that hardware earlier. Bringing the 1B to a similar standard closes the gap between the two variants that share much of their architecture.
CFM International is a joint venture owned equally by GE Aerospace and Safran. Its predecessor product, the CFM56, set a durability benchmark that operators have repeatedly invoked when discussing LEAP shop-visit intervals — and restoring on-wing maintenance intervals closer to CFM56 norms has been an explicit target of the reverse bleed system work.
Why operators care
Time on wing is a direct cost line. Every premature shop visit means an engine removal, a spare engine leased or held, and an airframe potentially out of service. For carriers operating 737 MAX fleets in the Gulf, South Asia and other hot, harsh environments, engines that need overhaul earlier than planned distort both maintenance budgets and fleet availability.
The certification does not fix the installed fleet overnight. New-build engines get the hardware from the 2027 production cutover, and existing engines will pick it up through the normal shop-visit cycle rather than through a dedicated retrofit campaign. That means the benefit arrives gradually, engine by engine, as aircraft come in for scheduled work.
Still, regulatory approval is the gate that had to be cleared. With the FAA sign-off in hand and industrialisation beginning, the durability improvements move from a development programme into a production plan — and operators finally have a date to plan around.
Sources: FlightGlobal, Aviation Week. Featured image: AI-generated by AviationShop. By Marco Bianchi.
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