Boeing Seeks Next-Generation Engine Details for Future Single-Aisle Aircraft

Boeing Seeks Next-Generation Engine Details for Future Single-Aisle Aircraft

Advancing Engine Technology for a 737 Successor

At the Paris Air Show, Boeing announced a new request for information (RFI) directed at leading engine manufacturers, seeking advanced ducted propulsion systems in the 30,000-pound thrust class. This initiative is part of Boeing’s ongoing efforts to develop a potential future single-aisle aircraft intended to succeed the 737. The company continues to favor ducted propulsion technology over open rotor or open fan designs for its next-generation studies, reflecting a strategic focus on proven engine architectures.

This latest RFI, reportedly the fourth issued by Boeing, signals a quiet but deliberate progression in the long-term development of a 737 replacement, targeting entry into service in the 2030s and beyond. While Boeing has temporarily paused near- and mid-term new product launches to concentrate on financial recovery and production stability, it remains committed to exploring technologies that could deliver at least a 20% improvement in fuel efficiency compared to the current 737 MAX family.

Industry Challenges and Market Outlook

The development of a next-generation single-aisle aircraft presents significant challenges. Industry analysts estimate that the total development costs could reach as high as $25 billion, with a payback period extending between 10 and 12 years. Despite these financial and technical hurdles, market sentiment remains cautiously optimistic. A recent survey by McKinsey & Company found that 84% of respondents expect a next-generation single-aisle aircraft (NGSA) to enter service by 2035 or earlier.

Boeing’s President and CEO, Kelly Ortberg, recently emphasized the company’s measured approach, highlighting three critical factors: market readiness, technological maturity, and Boeing’s financial capacity. “We’re not ready on any of those work streams today, but we need to be when the market is ready for a new aircraft,” Ortberg stated in an interview with Aviation Week.

Engine Manufacturers and Technological Developments

Engine manufacturers expected to respond to Boeing’s RFI include Rolls-Royce and Pratt & Whitney, both of which are also proposing geared, ducted turbofan engines to Airbus for its own NGSA program. The CFM International joint venture between General Electric and Safran is anticipated to provide details on a ducted engine variant drawing on technology from its Revolutionary Innovation for Sustainable Engine (RISE) program. While RISE primarily focuses on an unducted open fan design slated for testing with Airbus, components such as the high-pressure core could be adapted for a ducted engine configuration.

Safran’s Chief Technology Officer, Eric Dalbies, noted that while the RISE open fan aims for a 20% reduction in fuel burn, a ducted-fan version—believed to be named the Advance—would offer a more modest 10 to 12% improvement but at a lower cost. This ducted variant is thought to feature an 85-inch diameter fan. Although CFM has declined to comment on the ducted design, sources indicate that flight testing could take place on the Airbus A380 testbed currently used for open fan evaluations. Proposals for such modifications are reportedly under review by the European Clean Aviation research program.

Meanwhile, Airbus is pursuing a diversified strategy by exploring multiple engine technologies and advanced materials. This approach aims to balance the demands of high production rates with cost efficiency, a critical consideration for the economics of the single-aisle market.

As Boeing and its competitors continue to evaluate their options, the aerospace industry remains focused on achieving substantial efficiency gains while managing the considerable financial and technical risks associated with developing the next generation of single-aisle aircraft.