The General Electric GE9X is not just famous because it is larger. Rather, the aircraft is becoming exceptionally noteworthy for its massive fan blade, which pushes jet-engine efficiency to its absolute limits. It is entering a new bracket of engine efficiency, changing how aerospace engineers think about thrust generation to begin with. Instead of relying on smaller fans that accelerate a small mass of air quickly, the GE9X moves air much more slowly, boosting overall bypass ratio and propulsive efficiency. These physics translate directly into lower fuel burn for airlines, a critical piece of their profitability puzzle. For passengers, there are benefits as well, including lower carbon emissions and reduced noise generation.

This all sounds relatively straightforward until one remembers the catch that, as fans continue to grow in size, pretty much everything else gets more complicated. The nacelle of the engine also has to be made wider as a result, which adds significant drag. The fan case and blades also need to stay light but insanely strong, and ground clearance also becomes a major packaging problem. The engine itself also has to pass brutal certification tests for bird strikes, blade containment, vibrations, and overall durability. This dynamic engine is a combination of new materials and advanced design choices, such as composite fan blades and cases, all built especially to make this kind of engine practical on a massive aircraft like the Boeing 777X. We discuss the relevance of this massive fan blade, what engineering tradeoffs it forces, and how the GE9X’s design points towards the next era of ultra-efficient long-haul propulsion.

A Brief Overview Of The GE9X’s Predecessor: The GE90

It is pretty important to begin by noting that the GE9X engine certainly did not come out of nowhere. This engine was developed from the earlier GE90, an engine that shattered records and became iconic for powering Boeing 777 jets. This powerplant turned the Boeing 777 into the long-haul workhorse that we know today (especially the 777-300ER). The important reason why this engine was able to offer such impressive efficiency improvements is that it was larger than any other model to date.

Launched originally in 1990, the powerplant was GE’s first engine to exceed 100,000 lbf (445 kN), a thrust class previously nonexistent for commercial engines. The manufacturer pioneered this key technology that later became normal, with composite fan blades that save weight while ultimately maintaining strength. The airline’s defining feature was scale, with early versions that had a 123-inch (3.12 m) fan blade. The flagship best-selling model of this engine family, the GE90-115B, would eventually grow to around 128 inches (3.25 m) in scale, a size that offered an impressive bypass ratio and the propulsive efficiency needed for ultra-long-range flying.

Once in service, the GE90 was rated at 115,300 lbf (513 kN), a development that quickly made it the most powerful commercial turbofan engine ever developed. During stress testing, the engine actually proved it could exceed 127,900 lbf (570 kN), setting a benchmark that has yet to be surpassed. Ultimately, the GE90 proved that, with a bigger fan and advanced materials, this engine could be operationally viable, and it set a template that the GE9X would build upon.

An Overview Of The Boeing 777X

It is also important to keep in mind that the GE9X would not exist if it were not for the Boeing 777X, the jet for which this engine has been developed. The Boeing 777X is the next evolution of the 777 family, and it will similarly be a twin-engine model that offers long-haul flexibility, and it can provide a step-change in overall efficiency and capacity for the biggest overall global routes. The family centers on the Boeing 777-9 and the 777-8, both of which will be powered by the same engine. (There is a freighter variant also under development within the family).

This groundbreaking aircraft will have a massive 235-foot-5-inch (71.8 m) wingspan, which shrinks slightly at gates due to first-of-their-kind folding wingtips. This massive aircraft will be sized to carry around 426 passengers in a two-class layout, and the airline is looking to target 7,285 nautical miles (13,500 km) of range, all while the smaller Boeing 777-8 is listed at around 395 passengers, with a range of 8,745 nautical miles (16,190 km).

It is also important to keep in mind that the aircraft’s long-haul capabilities are only half of what makes the aircraft so appealing. The 777X will be one of the most efficient high-capacity widebodies to hit the market, a key reason why the jet is already selling well with hub-and-spoke carriers that serve high-demand trunk routes.

A Look At The Development Process For The GE9X

The General Electric GE9X was built as a clean-sheet evolution of the popular GE90 family, although manufacturer GE treated it as a full new engine program. The company had roughly a decade of technological maturation since it had developed the earlier GE90 model, and thus it had many decisions to make when it came to the engine’s fan, compressor, combustor, and turbine, all before it even began to file designs with aerospace regulators.

A key internal milestone was achieved in March 2016, when the First Engine To Test (FETT) accumulated around 168 hours of testing time at the company’s Peebles, Ohio, facility. These early tests validated the engine’s architecture, in-flight performance, and advanced material construction. From there, GE elected to step into certification testing, with a second engine kicking off the formal certification testing process in May 2017. A sprawling test campaign quickly followed, covering things like crosswind operability, endurance capabilities, icing resistance, and ingestion testing.

The engine then moved into flight testing on GE’s Boeing 747 flying testbed, with the first flight taking place in March 2018. A full 72 test flights accounting for more than 400+ hours followed. This program culminated on September 28, 2020, when the model achieved full FAA certification, after just around 5,000 hours and 8,000 cycles of overall testing. Additional testing continued after this date as the engine model sought extended-range twin-engine operational performance standards (ETOPS).

A Dive Into The GE9X’s Design

The General Electric GE9X’s design is essentially a two-piece construction. The design philosophy was to make the massive fan do more of the work and make the core extract more energy from every pound of jet fuel. The massive fan is located at the front of the engine, and it features just 16 composite blades, reducing weight and the drag created by the wake of fan blades. Advanced three-dimensional aerodynamics and new carbon-fiber structures keep blades thin yet tough for bird-strike and fatigue demands. Here are some specifications for the engine, according to GE’s direct filings with US aerospace regulators:

This giant and efficient fan supports a roughly 10:1 bypass ratio, ultimately meaning that more thrust comes from moving a larger mass of air in a much slower fashion. This produces less noise and is more efficient than the traditional, high-pressure jet exhaust. General Electric’s thermal efficiency in this engine is fairly incomparable. Its overall pressure ratio that exceeds 60:1 leaves a lot of competitors in the dust.

A modern combustor is designed to cut emissions while staying stable across a wider operating envelope. Making this survivable requires materials and manufacturing tricks, including ceramic matrix composites that can withstand incredibly high temperatures. This allows the engine to run hotter, wasting less energy on cooling air.

When Will We See The GE9X Enter Operational Service?

Once the General Electric GE9X was certified, it did not enter regular airline service because the jet that it was designed for, the Boeing 777X, was nowhere even close to being delivered to customers. The aircraft has been routinely hit with certification delays, meaning that it still remains far from actually entering service, and many analysts are dubious of Boeing’s timeline.

The GE9X engine was fully certified on September 28, 2020, a program milestone. It certainly is not the thing holding back the Boeing 777X program from achieving certification and taking off commercially. Boeing’s most ambitious forecasts do not see the aircraft being delivered to customers until at least 2027.

Therefore, the cleanest answer is that we may see the GE9X in service next year. However, there are still a lot of hoops Boeing will have to climb through before the engine powers a single revenue flight.

What Is Our Bottom Line?

At the end of the day, the GE9X is an incredibly capable, powerful, and efficient engine. The power plant will undoubtedly have a major impact on the market; the question now is more about the magnitude. Boeing is still struggling to get the 777X into the skies for commercial airlines.

Given Boeing’s extensive safety-related issues over the past decade, it is unsurprising that the Federal Aviation Administration (FAA) is taking its time certifying the jet. Even if the FAA were to speed up its timeline, it is unlikely that European or East Asian regulators would do the same (and those are the regions where most 777X customers are based).

As a result, it is fair to conclude that GE has done its job with this engine. It has produced a modern powerplant, one of the most advanced to ever be fitted underneath a commercial aircraft wing. The engine’s future, unfortunately, now sits in the hands of a somewhat troubled Boeing.