General Electric’s longstanding engine partners IHI, Snecma, Techspace Aero and MTU have been named as participants in the company’s new GE9X program now in development for the Boeing 777X long-range derivative family.

The group will collectively hold approximately a 25% share in the 105,000-pounds-thrust engine, which will make its first run in 2016. The shareholding is, however, significantly lower than the 36% share given to most of these same partners in 2005 to assist with development of the GEnx engine for the 787 and 747-8. The change partially reflects GE’s longer-term goal to increase vertical integration on new projects as well as the impact of the 2013 acquisition of gearbox specialist Avio. The Italian subsidiary, which will be contributing to the GE9X, took a 12% share in the GEnx as an independent partner.

IHI, which also provides parts for, among others, the CF34, GE90, GEnx and Passport engines, will be responsible for the design and manufacturing of components in the low-pressure (LP) turbine and the fan mid-shaft. Snecma, which is GE’s long-standing partner on the CFM International engine program and a participant in the GE90, will provide the 3-D-woven composite forward fan case, as well as the turbine rear frame. The composite fan case will build on technology developed for the CFM Leap engine case. Snecma will also participate with GE on the composite fan blades through its 50/50 joint venture company at CFAN.

Belgian-based Techspace Aero, which also supports the current CF34, GEnx and Passport programs, will be responsible for the design and manufacturing of the LP compressor as well as the manufacturing of the fan disk. MTU Aero of Germany, which currently supports several programs including the F110, CF6, GP7200 and GEnx, will design and manufacture the turbine center frame.

From an external perspective, the most distinctive feature of the GE9X will be its enormous 133.5-in. diameter fan. The size was settled after hovering in the 132-in. range for much of 2013. The enlarged fan is key to boosting propulsive efficiency and makes the GE9X the largest turbofan ever developed in terms of physical size. Although producing around 10,000 pounds thrust less than the GE90-115, the fan will be 5.5 inches wider than the 777 engine but will have only 16 blades, rather than the 22 of the current engine.

“When you invest in developing this technology you size it for the thrust required, so a number of trade studies have been completed to firm up conceptual configuration,” says GE90 and GEnx program manager Bill Millhaem. Although both versions of the 777X, the -8 and 9, are aimed at the same maximum takeoff weight of 750,000 lb. as the current 777-300ER, they will be able to fly farther and more efficiently due largely to the wider-span, advanced-composite wing of the new model. This enables the thrust requirement to be decreased from that of the GE90-115, and following the request late last year from Emirates Airlines for a final thrust bump, this has now settled at around 105,000 lb.

Although the GE9X blades will resemble those of the GE90, they will be constructed from a new fiber resin composite and have aerodynamic changes with more sweep and wider chord to improve pumping efficiency. “We have developed a new fan blade system that is stronger. It has gone through impact tests for the blades, which have a thinner leading edge,” says Millhaem. The changes also include a new metal leading-edge sheath. Testing of one-fifth to one-sixth scaled versions of the GE9X blades is being conducted in Boeing’s universal propulsion system (UPS) aero-acoustic propulsion simulator test rig in Seattle.

Initial tests focused on runs of a baseline 18-blade set similar to the GEnx to verify results against known performance characteristics from this 747-8/787 engine, and subsequently moved on to evaluate two GE9X 16-blade designs with different aerodynamic features. “We will downselect an aerodynamic configuration based on this testing then go back and redo impact tests with this final design. Then we will start into a more advanced test program before going to blade-out testing as we get closer to the final design size,” he adds.

Further tests of an 80% scaled version of the GE9X 11-stage HP compressor are planned for later this year at the company’s Massa, Italy, facility following initial evaluations early this year. “We met all our aeromechanical targets for durability and performance, so we feel that a pressure ratio of 27:1 is clearly within our capability. Overall we exceeded all our expectations,” Millhaem says.

The GE9X compressor pressure ratio growth from 19:1 on the GE90-115 and 23:1 on the 10-stage unit in the GEnx-1B has also raised turbine entry temperature by around 100 degrees. The engine will therefore incorporate a new disc alloy in the last stage of the HP compressor and the first stage of the two-stage HP turbine. Both stages will be air-cooled, while the second stage will incorporate a new blade design. Heat-resistant ceramic matrix composite (CMC) will be used for the first-stage nozzle and shroud, as well as the second-stage nozzle. “We will run CMC -9X style combustion liner, shroud and nozzle parts in a GEnx development engine by year-end,” says Millhaem.

Full-scale GE9X components will run in two builds of GEnx-1B engines in 2015 in the run-up to first full GE9X engine runs in 2016 and the launch of certification tests. First flight on GE’s 747 flying testbed is set for 2017, in readiness for first flight of the 777-9X the following year.