CFM International (GE + Safran) · Case study
CFM56-5B / -7B
The best-selling jet engine in history. The CFM56 powered the narrowbody market for three decades and proved the GE-Safran partnership that went on to build the LEAP.
Architecture
The CFM56 is a two-spool high-bypass turbofan that grafts GE's F101 core — developed for the B-1 bomber — onto a Snecma (now Safran) low-pressure system. A single fan and booster sit on the LP shaft; a nine-stage high-pressure compressor, annular combustor and cooled high-pressure turbine make up the core.
The combustor was offered in single-annular form and, on later low-emissions variants, a dual-annular configuration to cut NOₓ. Bypass ratio sits around 5 and the overall pressure ratio climbed steadily across the -5B and -7B variants as the family matured.
The cycle
The CFM56's success was as much about robustness as raw efficiency. A conservative, well-understood cycle gave long on-wing life and low maintenance cost — exactly what a narrowbody operator values — while incremental pressure-ratio and material improvements kept fuel burn competitive across a thirty-year production run.
Engineering significance
Tens of thousands of CFM56s were built, making it the best-selling jet engine ever produced. Just as important, it was the proving ground for CFM International — the GE-Safran joint venture — whose next engine, the LEAP, would inherit the narrowbody crown.
Applications
Airbus A320 family · Boeing 737 Classic / NG
Explore a representative turbofan cycle for this engine class in the interactive console.
Open the simulator →All figures are public-estimated and approximate, given for a representative variant; exact values vary by sub-model and rating. PropulsionLab is an educational project and is not affiliated with any engine manufacturer. Engine names are the trademarks of their respective owners.