Engine manufacturer CFM International (Stand G23) plans to test 15 Leap engines this year as part of a development program leading to certification of the Leap-1A for the Airbus A320neo next year. Also part of the program, the Leap 1B and -1C versions are to power the upgraded Boeing 737 Max and the new Comac C919 narrowbodies, respectively. The engine’s designers promise a 15-percent fuel burn advantage over the current CFM56.
The Snecma-GE joint venture began Leap-1A early icing tests at GE’s facilities in Winnipeg, Canada, in January. The same version is to undergo “block tests” measuring operability in extreme conditions, in September and October, CFM executive v-p Cédric Goubet told AIN. Early endurance tests also will be performed on the -1A this year.
A Leap-1B is to fire for the first time in June, nine months after the first Leap-1A (which shares a common turbomachinery with the -1C, making the two turbofans virtually identical). Although the -1B and the -1A are different engines, the experience gathered on the -1A is very useful, as it has validated some technologies, Goubet said. He referred to components such as the fan blades, which are made of carbon fibers woven in three dimensions, titanium aluminide alloy low-pressure turbine blades and ceramic matrix composite (CMC) engine shrouds.
The CMC is “a first in civil applications…the challenge is to flawlessly produce such sophisticated material in large volumes,” Goubet emphasized. Its main benefits are its reduced density, as it reduces the weight of the part by two thirds, and its ability to withstand high temperatures. Therefore, Snecma and GE engineers hope to use it in the future (sometime after entry into service) for high-pressure turbine blades. The latter components would then not require their current complex cooling air channels. They also are considering switching to CMC on the low-pressure turbine’s larger blades, as it may save weight, Goubet added.
Separately, 3D-printed components are being used in the Leap program. “On development engines, some vanes of the low-pressure turbine are made using an additive layer manufacturing process with titanium alloy,” Goubet said. On production engines, the fuel nozzles will be partly made from a nickel alloy via 3-D printing.
This year will also see the Leap’s first flights: GE’s flying testbed, a modified Boeing 747-100 equipped with one Leap-1C, is to take off from Victorville, California, in late March or early April, Goubet said. Such flight tests are required for certification. Flight-testing the Leap-1C will also help “de-risking” all Leap programs, he added.
The differences between the -1A and the -1C, which are found in the interface with the nacelle and the pylon, will not be negligible, however. (The pylon was recently delivered by China’s Comac.)
Testing continues with the 747 taking a Leap-1A to the skies in September. The -1B’s turn will come early in 2015. Planned certification dates for the Leap-1A and -1B are, respectively, June 2015 and February 2016. Certification of the -1C is penciled in for June 2015, simultaneously with the -1A, but Goubet added this is “pending a pragmatic approach of potential adjustments in the C919’s schedule.”
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