GE Aerospace arrives at Farnborough with one eye trained on the future – specifically on developing an open-fan engine for future narrowbody jets – and the other focused on recovering from supply chain troubles that continue constraining engine production.
Meanwhile, the Ohio company is working through – and, executives insist, fixing – durability problems affecting its best-selling Leap turbofan.
This year’s Farnborough exhibition also marks the first big summer air show since GE Aerospace became a standalone independent company following parent General Electric’s spin off in April of GE Vernova, which had been its last non-aerospace division. GE Aerospace, with 52,000 employees and $32 billion in 2023 revenue, is now the sole remaining business under once-massive American industrial conglomerate General Electric.
Speaking to reporters ahead of the Farnborough show, GE vice-president of engineering Mohamed Ali describes the company as entering a new era after completing a decade-long “process of renewal” that involved introducing several new powerplants. Those include the Passport business-jet turbofan (which replace CF34-3s), two widebody aircraft engines, the GEnx and GE9X (successors respectively to CF6s and GE90s), and CFM International’s Leap (which replaces CFM56s). GE owns CFM in partnership with Safran Aircraft Engines.
Now freshened up, GE is turning more resources into defining what comes next.
“It is time to think about, what does the future bring?” Ali says. “What are new technologies that we need to bring into the next decade and beyond that will set the stage for a sustainable… future of flight?”
The questions are somewhat rhetorical, as GE makes no secret about its plan: to develop a new gas turbine with an open-fan architecture (meaning no nacelle or other surrounding structure) that will power the next generation of narrowbody jets and be 20% more efficient than Leaps.
GE and Safran are progressing toward developing the turbine through CFM’s Revolutionary Innovation for Sustainable Engines (RISE) programme. They aim for their open-fan engine to be ready by the mid-2030s, about when analysts expect Airbus and Boeing will introduce clean-sheet narrowbody jets to replace A320s and 737s.
“Together with our partner Safran… we decided to put a line of the sand,” Ali says. “We set an ambitious goal.”
Three years after CFM revealed RISE, GE insists it remains more committed than ever.
The aerospace industry absolutely needs future engines to be meaningfully more efficient, but current architectures cannot get there, says GE chief executive of commercial engines and services Russell Stokes.
For decades, engineers boosted turbofan efficiency by developing models with increasingly larger fans – and hence greater bypass ratios (the ratio of the amount of “bypass” air driven around the core to the amount of air moving through the core). Modern turbofans have bypass ratios of 11:1 or 12:1, Ali says. “You really want… as big of a fan as possible that is rotating as slow as possible, to generate as much of the thrust as you can.”
But fans enclosed in today’s turbofans are nearly as large as is practical, says Ali. That is because efficiency gains derived from even-larger fans would be cancelled out by weight and drag penalties created by larger nacelles and other surrounding structures.
But open fans have no nacelles nor surrounding structures. Their fans, which spin free in the outside air, can be much larger without nacelle penalties.
The “open fan gives you this revolutionary innovation that changes the curve completely”, says Ali. “We are going for a bypass ratio of somewhere between 45 and 60.” CFM also says hybrid-electric capabilities will add to the open fan’s efficiency, and that the powerplant might be capable of burning hydrogen.
Open fans – also called propfans – are not new. Spurred by oil shortages in the early 1970s, several companies began developing the turbines, including under NASA’s “Advanced Turboprop Project”. The efforts continued into the 1980s, with GE itself developing a model called the GE36 Unducted Fan, which it flight tested using both a 727 and MD-80.
Way back then, open fans seemed the way of the future. “All indicators pointed to the introduction of the new turboprops on commercial aircraft by the 1990s,” says a NASA document.
In the end, however, the technology fell aside as fuel prices declined and amid technical challenges. Notably, lacking nacelles tends to make open fans much louder than traditional turbofans, creating difficulty in meeting noise regulations. Also, while turbofans have containment rings to prevent uncontained engine failures, opens fans do not. Engineers must therefore find other means of ensuring failures do not spray shrapnel capable of piercing an aircraft’s cabin or other structures.
Ali says GE continued working on open fans after the GE36 effort faltered, and that “two fundamental” advancements in recent decades have made the architecture suitable for powering the next-generation of narrowbody jets.
First, while the GE36 had two counter-rotating fans – a “very complex” architecture – the RISE powerplant will have a single fan (with variable pitch blades) positioned ahead of stationary outlet guide vanes, says Ali. He adds that a decade of wind-tunnel tests have proven that the single-fan design can achieve GE’s efficiency and aircraft-speed targets.
Second, Ali says today’s “supercomputers” have allowed GE to design an open-fan engine that will be quieter than Leaps, adding, “We are one of the largest users of supercomputing ability in the world”.
Work is progressing. GE’s French counterpart Safran has started wind-tunnel testing an open fan that is one-fifth the scale of the ultimate envisioned engine. The partners aim by mid-decade to begin ground testing a demonstrator, and in the second half of the decade intend to begin flight tests using an A380.
The efficiency of the design means an engine core the size of that found in a business jet turbofan can power an open-fan engine for a narrowbody jet (and with a fan roughly as wide as that of a GE9X), GE says.
Therefore, GE will use the same core found in its 20,000lb (86kN)-thrust Passport 20 to power the RISE open-fan demonstrator, which will generate about 30,000lb of thrust, Ali says. “That’s how much efficiency we are talking about.”
GE’s RISE work is progressing on multiple fronts. It has developed a next-generation high-pressure turbine – tests have shown “incredible” efficiency and durability, says Ali – and started developing a “compact core” (that burns hotter and at higher pressures, boosting efficiency) under NASA’ Hybrid Thermally Efficient Core (HyTEC) programme.
GE is meanwhile advancing electrification technologies for RISE. Under HyTEC’s Turbofan Engine Power Extraction Demonstration effort, the company is evaluating hybrid-electric technologies by integrating multiple electric motor-generators with a Passport engine. The motors will inject electricity into the engine and the generators will extract electricity from it, with the components working based on phases of flight. GE has already completed separate test of the motor-generators and of the engine, and is now preparing to integrate the components for hybrid-electric engine ground tests.
Meanwhile, GE is developing an entire megawatt-class hybrid-electric propulsion system under NASA’s Electrified Powertrain Flight Demonstration project. It will integrate the system into a Saab 340B and plans to begin ground and flight tests in partnership with Boeing around mid-decade. “We are doing the flight-readiness testing… right now,” Ali says.
Whether RISE will lead to an open fan eventually powering a new narrowbody commercial jet remains uncertain. But Ali notes that naysayers once also dismissed advancements now common in GE turbofans, like composite fan blades and ceramic-matrix-composite materials.
Neither Airbus nor Boeing have revealed many details about their next narrowbody jets, let alone committed to engines. But Boeing CEO David Calhoun has said the 737’s replacement must be 15-20% more efficient. He also said CFM’s open fan might be compatible with the high-wing configuration of the X-66A truss-braced wing demonstrator Boeing is developing in partnership with NASA. Boeing says that aircraft – a heavily modified MD-90 – will help it evaluate technologies and designs for what comes next.
GE executives clearly intend to link the company’s brand to its ambitious efforts to develop fuel-saving technologies. But there is no escaping real challenges GE faces in the here and now.
Like other aerospace manufacturers, it has been stricken by supply chain troubles and disrupted by Boeing’s issues. At the same time, GE has needed to address durability troubles affecting Leap powerplants, particularly those operated in dusty environments, such as in the Middle East.
GE is not alone in such struggles. Pratt & Whitney’s (P&W) competing PW1100G – a second power option for Airbus A320neo-family jets – has suffered reliability and maintenance troubles, including an ongoing issue that forced P&W to recall thousands of the engines for inspections and replacement parts.
As for Leaps, Stokes says “just a couple” of components have suffered durability problems. GE has responded by developing a “durability upgrade” composed of new high-pressure turbine blades and “a reverse bleed system that provides cooling air after engine shutdown, thus mitigating the coking of unburned fuel in the nozzles,” GE has said.
The company plans this year to introduce the changes in updated Leap 1As, which power Airbus A320neo-family jets, and next year in updated Leap 1Bs, which power 737 Max, Stokes says.
He notes the airline industry has not yet fully recovered from the Covid-19 downturn. But it is close. The number of flights powered by GE and CFM engines jumped 18% year on year in 2023. Since then, growth has slowed to a predicted mid-to-single-digit year-on-year percentage rate both this year and next, Stokes says.
GE is among many companies that have struggled to meet production goals in the post-Covid environment.
Forged and cast metallic engine components have been particularly short in supply, analysts have said. But in March GE CEO Larry Culp said lack of skilled workers is the underlying problem. “You can boil it down to labour,” he said, noting aerospace companies throughout the chain lost many veteran workers during the pandemic.
GE has aimed to be delivering 2,000 Leaps annually by 2025. It has a way to go. The company delivered 1,570 Leaps in 2023. In the first quarter of 2024, it delivered 367 of the engines, up just one year on year.
The company is taking steps to get ahead of the issues. In March, it disclosed plans to spend $650 million this year on efforts to improve quality and boost output – about twice the $335 million it spent on such projects last year. The funds will “strengthen the company’s US supply chain, helping suppliers build and maintain capacity and capabilities needed for sustained growth”, GE said. The firm hired 900 engineers last year and plans to hire that many this year.
“We’re focused on making sure that we can meet the production ramp to support demand and the order books that have already been put in place,” says Stokes.
The industry’s troubles have kept Airbus and Boeing from delivering as many jets as they planned. Boeing faces other, unique hurdles. In February, it slashed 737 Max production in response to safety and quality concerns arising from the 5 January in-flight blow out of an Alaska Airlines 737 Max 9’s door plug. Investigators have said Boeing workers never secured that plug before delivering the jet.
SERVICES DEMAND SURGES
Unable to get their hands on enough new jets, some airlines have cancelled growth plans and are keeping older 737s and A320s flying longer than previously planned, driving up demand for maintenance. As a result, GE anticipates demand for CFM56 shop visits will peak in 2026 or 2027, not in 2025 as previously expected.
“Retirements are lower than what we had projected at the beginning of the year,” Stokes says. “Given some of the delivery challenges, we’re seeing an increase in the aftermarket side of the business.”
Indeed, GE’s revenue from commercial engine services jumped a staggering 30% year on year in 2023, to $16.7 billion. Growth slowed to 12% year on year in the first quarter of 2024.
The company is expanding its service capabilities, planning in September to open a Services Technology Acceleration Center near Cincinnati that will focus on developing improved engine inspection and repair technologies. The facility will be GE’s first to use a new process called “non-destructive open-beam x-ray fluorescence spectroscopy”, or XRF, which can help identify anomalies in metallic components.
Massachusetts material research firm Bruker helped GE develop the technology, which museums and auctioneers already employ to identify forged art.
“XRF provides a view of the part’s chemical composition that can help a service engineer more-readily spot anomalies,” GE says. The process will help technicians identify “airworthy repaired parts that can be returned to the field in lieu of replacing them entirely with new parts. This will help reduce supply chain constraints”.
