Story ID: 734 GE9XUpdate
GE9X On Course Flight Testing In 2017
By: Charles Alcock
Caption: Ground testing has started of the first 100,000-pound-thrust GE9X turbofan, which is the largest-ever commercial aircraft engine.
Word Count: 624
It is now three months since GE Aviation started ground testing the first full GE9X development engine at its Peebles, Ohio facility. That was on March 25 and, according to the manufacturer, this First Full Engine to Test (FETT) stage has been achieved much earlier than usual for a complex powerplant development—just six months after the design was finalized—and this stands the GE9X in good stead to complete certification as planned in 2018.

The 100,000-pound thrust engine is the sole powerplant for Boeing’s new 777X long-haul airliner. With a front fan that is 134 inches (3.4 meters) in diameter, the GE9X lays claim to being the largest-ever commercial aircraft engine.

Technology standouts for the 27:1 pressure ratio engine, which has an 11-stage high-pressure compressor, include a composite fan case and 16 fourth-generation carbon fiber composite fan blades. The GE9X promises a 10 percent reduction in fuel burn compared to the GE90-115B engines that power the existing 777-300ER, and a 5 percent improvement in specific fuel consumption compared to any currently-available twin-aisle airliners, plus noise compliance within ICAO Stage 5 limits.

GE (Chalet P2) has made extensive use of carbon matrix composites (CMC) in both the combustor and turbine. The high-pressure turbine features CMCs in the stage one and two nozzles and stage one shrouds, and blades that use advanced cooling technology; while the 3D lightweight low-pressure turbine blades are produced at Avio Aero using a titanium aluminide (TiAl) additive-manufacturing process.

The engine includes the third-generation TAPS III (twin-annular pre-mixing swirler) combustor which pre-mixes air and fuel prior to combustion for leaner burn, creating fewer harmful emissions than conventional combustion systems. The unit includes 3D additive-manufactured fuel nozzle tips, a new combustor dome design and ultra-lightweight, heat-resistant CMC inner and outer liners.

GE began maturation testing for the GE9X some five years ago and its approach from component level preparation all the way up to the FETT stage has been to demonstrate complete operability as an integrated propulsion system. Next year, certification and flight testing will begin on GE’s flying test bed aircraft.

Ted Ingling, the newly appointed general manager of the GE90/9X program, told AIN that eight engines will be involved in ground testing, with a ninth set aside for flight testing. “In the tests so far the engine is performing absolutely as expected. This is a full shakedown of the engine that will allow us to verify the architectural choices before we make the second engine,” he explained. “We’re looking at fundamental architectural choices that would be harder and more difficult to change in the future.”

So far, the GE9X has met all expectations in terms of thrust and operational requirements, claimed GE. “There have only been a few minor items to tweak, such as mechanical issues in the air foil stage,” said Ingling. “It’s all in a very sound position and that allows us to quickly move on to start testing the second engine early in 2017.” The company has already started making components for this second ground-test engine.

While the first FETT engine will not officially be part of the certification program, GE plans to use it for some icing testing next winter in order to get a year’s head start on this phase of the development. Meanwhile the Boeing 747-400 flying test bed has already been prepared to accommodate the larger engine.

GE’s main partners in the GE9X program are Japan’s IHI Corporation, Safran subsidiaries Snecma and Techspace Aero, and MTU Aero Engines of Germany. To date, the U.S. company has booked orders for around 700 of the new engine.