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CFM studies Airbus-specific variant of CFM56 engine

CFM continues to study a more efficient variant of its Airbus A320 family turbofan engine, the CFM56-5B.

The advances will be based in part on progress to date on the CFM56-7B Evolution turbofan, an upgrade of the CFM56-7B engine powering Next-Generation Boeing 737s. The newest 737, which will include aerodynamic improvements and a new Boeing "sky" interior, is set for entry into service in June 2011. ATI reported in May that Airbus and CFM had begun discussing the upgrade.

The CFM56-7BE engine has 9% fewer aerofoils as well as reshaped blades and vanes in the high- and low-pressure turbines to increase airflow through the engine and reduce operating temperatures. Combined with Boeing-designed modifications to the engine nozzle and plug, the engine will deliver 1% improvement in specific fuel consumption and 4% less maintenance costs. For the airframe in total, Boeing is advertising a 2% decrease in fuel consumption.

Boeing programs director at CFM Kris Shepherd says engineers are "trying to overshoot" the 1% target for the engine "a little bit to get some margin". In-flight data on the new engine will be available soon, as CFM 50/50 partner GE plans to begin flying a prototype on its 747-100 testbed in the US in February. Tests are expected to be complete in March, after which Boeing will begin testing the -7BE for the US Navy's P-8A Poseidon application, a variant of the Boeing 737-800.

In parallel, partner Snecma is now running "block tests" of severe operating conditions with an engine on a test stand at its facilities in France. "If it's going to break, this is when it's going to happen," says Shepherd of the Snecma tests. Included is a simulation of 150 consecutive take off and landing sequences, with the engine running as hot and fast as possible.

Shepherd says CFM has "been in discussions" with Airbus regarding a CFM56-5B evolution engine for the A320 family. Though some of the -7BE's low-pressure turbine technologies are already included in the -5B models, Shepherd says other possible changes will lead to further improvements of the engine. "It's too preliminary to talk about," he adds.

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