Boeing Keeps an Open Mind on Open Fan as It Rebuilds 737 Output

There is a prevailing view within the aerospace industry that Boeing is skeptical of CFM International’s RISE open-fan engine concept, but Boeing Commercial Airplanes (BCA) president and CEO Stephanie Pope says that the airframer has not definitively ruled out such an engine architecture for its next clean-sheet aircraft design.

Airbus has partnered with CFM International, the French-U.S. joint venture between Safran and GE Aerospace, to explore potential future applications of an open-fan engine concept. Boeing, on the other hand, has generally signaled a preference for a lower-risk propulsion approach for the eventual successor to the 737 Max family.

Ahead of the 2026 Farnborough International Airshow, Leeham News and Analysis asked Pope whether Boeing could be convinced of the open-fan concept’s potential. She did not respond with a hard “no” and signaled a willingness to keep engaging with engine innovators.

“We are interested and curious about all the technology maturation [and] how that is going to drive durability,” she said. “Typically, the two priorities for us when we’re looking at engine technology is the fuel consumption or the fuel efficiency that that’s going to drive, and then how it integrates with the airframe and airplane overall.”

Pope adds that it is “too early to have a position” but maintains that Boeing is “actively engaged with GE and learning more every day as that technology matures.” Her comments suggest Boeing is essentially doing its homework on the open-fan concept, and notably, they do not shut the door on it entirely.

Propulsion’s place in the equation will likely make it a major theme at the Farnborough show. Much of the discussion will center on RISE (Revolutionary Innovation for Sustainable Engines), a program that CFM touts as a potential game-changer for commercial airliners.

While RISE could provide significant efficiency gains relative to current-generation turbofans, such as CFM’s Leap and Pratt & Whitney’s geared turbofan (GTF) engines, notable technical hurdles must be addressed before open-fan engines are considered commercially viable. Specifically, blade-out failures could pierce the passenger cabin, though GE has emphasized that composite fan blades have never been involved in such an incident. Guarding against blade-out events by armoring the fuselage would add weight to the airframe, potentially offsetting the greater fuel efficiency provided by the engines themselves. GE says that these technical hurdles can be overcome.

But the commercial sector finds itself stuck in a holding pattern: engine makers are pursuing multiple development pathways and waiting for clarity on the next single-aisle aircraft platforms, while airframers are working through huge order backlogs and waiting for engine technology to mature before launching their next clean-sheet designs. Nobody is making a big move in the meantime. Boeing, meanwhile, has largely observed from the sidelines, seeming lukewarm on the radical design.

Pope maintained the company’s stance that a 737 replacement is not coming soon, as Boeing is focusing on stabilizing its finances and securing FAA certification for the 737 Max 7, Max 10, and 777-9.

“We’ve been very consistent when we talk about the next new airplane,” she said. “We talk about it in three buckets: We have to be ready...we have to have capacity. Right now, all of our engineering capacity is focused on certifying those three airplanes. And we have to have our financial health recovered, so we have the investment.” The third “bucket,” according to Pope, is assessing the market’s readiness for a new commercial airliner. “We’re listening constantly to our customers,” she said. “Then, the technology has to be ready.”

Proof in the Production

Since succeeding Stan Deal as head of BCA in March 2024, Pope has been tasked with steadying the airframer’s long-beleaguered aircraft production system and expanding factory capacity in a bid to regain single-aisle market share ceded to Airbus.

Ramping up production of the 737 Max program has been far from straightforward. Following the industry-shaking mid-flight blow-out of an exit door plug on an Alaska Airlines-operated 737 Max 9 in January 2024, Boeing’s narrowbody output has been constrained by a series of incrementally raised FAA-mandated production caps.

Heading into Farnborough, momentum finally appears to be in BCA’s favor. The FAA has increased Boeing’s monthly 737 production cap to 47 jets from 42, and Max production is slowly ramping up at the airframer’s newly established North Line in Everett, Washington. Company executives also say the engine anti-icing issue has been resolved, clearing the way for certification of the Max 7.

“I’m really proud of the progress our team has made,” Pope said, adding that the results reflect BCA’s adherence to its safety management system.

Establishing a fourth 737 production line, in addition to the three well-established lines at Boeing’s primary narrowbody production facility in Renton, Washington. After loading the first two 737 Max 10 fuselages onto the line earlier this month, Boeing is starting with a low-rate initial production pace for the first 10 aircraft while it works out kinks in the line.

While the facility has the tooling required to produce Max 8s, 9s, and 10s, Pope says it is envisioned primarily as supporting the Max 10.

Aircraft assembled on the North Line will likely be delivered to customers starting “sometime next year,” Pope says. “We want to make sure they deploy the SMS [safety management system], they go slow and build at the rate that they’re ready for.”

Eventually, the goal is to surpass Boeing’s highest-ever monthly 737 production rate of 52 aircraft—reached prior to the Max crashes—and potentially reach as high as 63 per month. For now, BCA is focused on stabilizing 737 Max production at 47 aircraft per month.

Elsewhere across BCA’s aircraft programs, Boeing is also building a second final assembly line for 787 widebodies at its North Charleston, South Carolina, factory. It aims to eventually reach a monthly production rate of 14 Dreamliners, after stabilizing at a rate of eight per month in the first quarter.

Last month, Boeing received FAA approval to proceed with TIA Phase 4B certification testing for the 777X, a critical step toward securing type certification for the long-delayed widebody derivative.

“There are five TIAs that we have to work through,” Pope said. “4B is the last with what I’d say is a significant amount of work, predominantly focused on systems like avionics. We just got the approvals to go complete that work, which is a big milestone.”

Boeing executives recently estimated that the company is roughly halfway through certification flight testing with the FAA. Despite some rumblings that securing ETOPS certification for long-range overwater flying could delay the 777-9’s certification, Boeing insists it is still on track to hand the first of the massive twinjets to airlines in 2027.

“I think the team continues to see positive momentum, both in restoring trust with our customers, our regulators, and our suppliers,” Pope said. “There’s still a humble approach to what we’re doing, and I think that’s really what’s driving the results.”