CFM LEAP-1A Maintenance Guide Update
Firdaus Adris
Head of Engine Services at Shannon Technical Services (APAC)
CFM has updated the LEAP-1A Maintenance Guide, providing a clarification that may influence Performance Restoration (PR) planning.
What Changed
The latest 2025 revision clarifies that the combustor is now formally categorised as on-condition. As a result, it does not need to be overhauled during a PR unless supported by inspection findings.
This aligns with a previous change regarding the High-Pressure Compressor (HPC), which was also removed from the mandatory PR scope. Both updates reflect a shift towards condition-based, data-driven maintenance decision-making.
Technical Context
On-condition maintenance practices are well established in the industry. For example, Rolls-Royce’s TotalCare programme applies a similar approach to prolong on-wing life while maintaining airworthiness.
Exhaust Gas Temperature (EGT) margin recovery is a primary objective of PR shop visits. While the combustor may contribute to overall thermal performance, field data and operational experience indicate that EGT deterioration is more commonly driven by turbine blade erosion and wear in the high- and low-pressure turbine sections. In particular, changes in clearances within these hot-section modules often have a greater impact on EGT margin than the combustor alone.
Replacing the combustor in isolation may not significantly improve EGT margin unless these other modules are also addressed. Regular water washing is one recognised method for helping to manage EGT margin deterioration over time.
Recommended Actions
Operators and lessors may wish to:
- Review lease language to ensure PR expectations are clearly defined
- Reassess shop visit cost models based on the updated maintenance scope
- Align with MRO partners on the interpretation of the revised guidance
- Monitor EGT margin performance to support planning decisions
The recent update introduces additional flexibility in defining shop visit scope and may influence maintenance planning approaches. As lease return conditions and commercial expectations can vary, coordination between technical teams, lessors, and MROs remains important.
If you would like support in understanding how these changes could affect maintenance planning, lease transitions, or MRO negotiations, our team is available to assist.
This summary is based on an internal review of LEAP-1A technical documentation and is provided for informational purposes only. For authoritative maintenance guidance or official interpretations, please consult directly with CFM International.
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