LEAP-X Engine Core Ready For Bench Testing

By Michael Mecham

CFM International expects the first bench tests of the full-scale core for its LEAP-X next-generation, single-aisle demonstration engine to begin the first week of June at GE Aviation’s Building 500 Development Assembly Center in Evendale, Ohio.

That event triggers a three-year push by the GE-Snecma CFM partnership toward full-engine tests in 2012 and the potential certification in 2016 of a successor to the CFM56-5B/7B to power replacement jets for the Boeing 737 and Airbus A320 families. CFM56 is the best-selling commercial jet engine in history.

But while CFM’s LEAP-X program has kept to the schedule outlined at its debut at last year’s Farnborough air show, its managers are no closer to knowing what Airbus and Boeing have in mind for 737/A320 replacements.

Vague Target Date

Without more guidance by about 2012, CFM will put LEAP-X on hold, says GE Executive VP Chaker Chakrour, who also is CFM56 project manager.

“Going forward is really a function of what the airplane guys do,” he says. “I’d love to know where they are going because it would make it easier for me to position [LEAP-X].”

The soft target date for the 737/A320 replacement is said by many, but not Airbus and Boeing, to be about 2018. But Chakrour is increasingly uncertain. Should such a date not firm up, CFM is prepared to push harder on the open rotor technology development it already has under way.

The technology would build on LEAP-X core technology but faces significant installation challenges, notably because it is noisier than other advanced technologies and requires an open-bladed rotor with a diameter as large as the fuselage of a 737.

As CFM’s new baseline engine, LEAP-X is to achieve a 16% savings in fuel consumption over CFM56-5B/7B technology, a 10-15 dB lower noise level than current Stage 4 standards, and 60%-plus improvement in NOX emissions over current CAEP 6 levels.

The fuel burn improvement comes from a combination of an optimized bypass ratio of 10:1, pressure ratio of 20:1 and a 16:1 compression ratio from a single-stage turbine.

Working Together

The first full-scale test core has been built up from individual components and modules already tested individually, says LEAP Program Director Ron Klapproth. Those modules must now be bench tested at various altitude, pressure and combustion stress levels to see how well they work together, compared with CFM’s analytical model. The test engine has about 2,000 sensors and gauges built into it.

Six engines will be used in the three-year test program, which will go through three iterations for the core development before CFM is ready to move on to a production core.

CFM has been briefing airframe makers on its progress with the LEAP-X program, which includes initial bench testing of the MASCOT engine in Villaroche, France. MASCOT began cross-wind testing this week at GE’s Peebles, Ohio, test facility. Snecma developed MASCOT using light-weight woven composite fan blades. The blades represent a technology breakthrough because they are stiff enough to withstand bird strikes, just as the much larger and stronger blades of GE90s that power Boeing’s latest generation 777s and its coming 787 can, she says.

Photo: Eric Drouin, Snecma

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