GE9X continues march toward certification

Testing comes after 10 years of technology maturation for GE9X components

July 14, 2018 Photo(s): GE Aviation

GE Aviation has successfully completed one-third of the 25 major test campaigns required for certification of the GE9X, and is on track to certify the engine next year. GE9X, the largest commercial engine in aviation history, will power Boeing's new 777X aircraft.

"We're really hitting our stride with the program, and I am very pleased with progress toward certification," said GE9X General Manager Ted Ingling. "The engine is meeting all its performance objectives with no significant findings, which shows the value of the most extensive technology maturation ever on a GE engine program."

Completed tests include crosswind operability, high-pressure turbine stress, icing, emissions, water ingestion and the first phase of flight testing on GE's flying testbed. A total of eight engines are involved in the certification program, with efforts focused at three key sites: GE Aviation's massive engine testing facility in Peebles, Ohio; the Testing, Research and Development Centre (TRDC) in Winnipeg, Canada; and GE Aviation flight test operation in Victorville, California.

Key program milestones to date include:

  • First Engine To Test (FETT), March 2016 - the first production-configured GE9X accumulated 168 hours and 162 cycles at the Peebles Test Operation, validating engine architecture, aerodynamic efficiency and materials performance in advance of the certification program.
  • Second Engine To Test (SETT), May 2017 - firing of the second production-configured engine marked the start of the certification program. The engine was used to verify sea-level performance and endurance block testing.
  • >First Flight, March 2018 - Mounted to a specially-designed pylon on GE's 747 flying testbed, the fourth production-configured engine accumulated a total of 105 hours of flight time during 18 flights, verifying performance across a range of altitudes and flight conditions. A second phase of flight operations on the flying testbed is slated to begin later this year.

Building on Success

GE9X is considered the fifth evolution of the legendary GE90, which helped revolutionize long-range, twin-engine service with the Boeing 777. Since entering into service with British Airways in November, 1995, close to 2,600 GE90s have been delivered to air carriers worldwide for both passenger and freight operations. The fleet has logged more than 80 million flight hours and nearly 12 million cycles.

Twenty-five years ago this summer, GE90 was at a similar stage of its certification program. The first engine to test milestone was met in March, 1993. First flight on GE's flying testbed occurred in December of that year, with certification following in February 1995. It was the world's largest, most powerful engine, featuring a 20:1 compressor pressure ratio and wide-chord composite fan blades, an industry first. But success was anything but assured in the early days of the program.

GE90 was developed in the early 1990s in the midst of a profound downturn in airline industry fortunes. GE was locked in a three-way battle to convince airlines that its clean-sheet design was technically superior to offerings from other engine manufacturers. The ultimate success of the GE90 program lay in anticipating that growth versions of the engine would be needed as carriers embraced the efficiency of long-range twin-engine operations. While originally conceived for a 76,000-pound thrust requirement, GE's engineers designed an engine architecture capable of up to 125,000 points of thrust.

The baseline GE90 was certified at 84,700 pounds of thrust. When it entered service in 1995, GE already was testing the GE90-94B, and would go on to become the exclusive engine provider for longer range and freight versions of the 777. The GE90-115B, the largest of the original GE90 variants, is rated for just over 115,000 pounds of thrust and holds the current record as the world's most powerful engine at 127,900 pounds of thrust.

Technology Maturation

The GE9X program represents the most extensive technology maturation effort in GE's nearly 50 years of commercial engine development. The GE9X is designed to deliver a 10% improved aircraft fuel burn versus the GE90 -115B-powered 777-300ER. It has a bypass ratio in excess of 10:1, and a 60:1 overall pressure ratio.

To ensure groundbreaking performance can be delivered with engine reliability comparable to the time-tested GE90, the GE9X team devised an extensive series of component development tests that lasted for about a decade. The compressor, which boasts a 27:1 pressure ratio, is fundamental to the engine's performance, and engineers began testing and maturing this component more than five years ago. The program also included tests of the fan, combustor and other key components. The first full-assembled core ran in 2015, leading to FETT in March 2016.

An additional focus of the technology maturation involved two phases of testing of ceramic matrix composite components in a GEnx demonstrator engine. GE9X represents the most extensive use of ceramic matrix composites in a GE engine, including the inner and outer combustor liners, stage one high pressure turbine shrouds and stage one and stage two high pressure turbine nozzles.

Developed and industrialized for aviation applications by GE, CMCs consist of silicon carbide ceramic fibers and ceramic matrix and are enhanced with proprietary coatings. With one-third the density of metal alloys, these ultra-lightweight CMCs reduce an engine's weight, which improves fuel efficiency and durability. CMCs are also more heat resistant than metal alloys, requiring less cooling air and increasing engine efficiency.

With almost 700 GE9X engines on order, the GE9X engine will be in the 100,000 pound thrust class and will have the largest front fan at 134 inches in diameter with a composite fan case and 16 fourth generation carbon fiber composite fan blades. Other key features include; a next-generation 27:1 pressure-ratio 11-stage high-pressure compressor; a third-generation TAPS III combustor for high efficiency and low emissions; and CMC material in the combustor and turbine.

IHI Corporation, Safran Aircraft Engines, Safran Aero Boosters and MTU Aero Engines AG are participants in the GE9X engine program.