The CFM56-7B turbofan engine was initially developed to provide the Boeing 737 Next Generation (NG) operators with higher thrust, lower maintenance costs and improved efficiency than its predecessor, the CFM56-3. The engine has achieved outstanding reliability since its entry into service and is rated from 18,500 lbf to 27,300 lbf. The -7 has been subject to very demanding circumstances while still being able to achieve outstanding rates.

Due to its reliability it enabled the CFM56-7B-powered Boeing 737 the first aircraft in its class to be granted 180-minute Extended-Range Twin-Engine Operations (ETOPS) approval by the U.S. Federal Aviation Administration (FAA). Obviously this resulted in the ability of airlines to operate their aircraft with a far greater route-scheduling flexibility. Besides commercial operators the CFM56-7B is operated by military customers as well. The U.S. Navy selected the engine to power its C-40A, a military 737 variant, for its Unique Fleet Essential Airlift Replacement Aircraft program.

Examples of aircraft that are powered by the CFM56-7B

The higher performance offered by the engine is mainly due to its new 61-inch titanium wide-chord fan, a new core and low pressure turbine, all of which have been developed using state-of-the-art 3D aerodynamic design methods. Furthermore, the CFM56-7B incorporates a new-generation electronic engine control system, the FADEC, or Full Authority Digital Engine Control. In order to satisfy the most environmentally conscious airlines, the CFM56-7B is offered with a double annular combustor (DAC) on option.

The high-pressure turbine features blades made of the N5 single-crystal alloy, for significant improvements over the CFM56-3 engine, namely; lower operating temperatures with higher exhaust gast temperature (EGT) margins for greater on-wing durability, and a Thrust Specific Fuel Consumption (TSFC) which is reduced by more than 8%.

Another important design objective of the CFM56-7B was to reduce maintenance costs by 15% over the CFM-3C1 engine at a maximum thrust of 23,500 pounds. As said, since the -7B retained the exemplary reliability of its predecessor it was granted 180-minute ETOPS certification from the FAA less than two years after its introduction.