Engine developments
Update on powerplant programs from major manufacturers.
By Owen Davies
Contributing Writer
This has been a quiet period of methodical progress for aircraft engine makers. Few new powerplants have arrived on the scene, but the research and development (R&D) programs that were under way when we last surveyed the field (Pro Pilot, May 2024, p 10) continue as planned, for the most part. Where there is turmoil, it inevitably emerges from the visions and revisions of Washington policy makers.
GE Aerospace
In July, after substantial delays, the company delivered its first production GE9X to Boeing for the 777-9, which is currently in certification trials. Certification and large-scale engine deliveries are expected in early 2025.
The company has also delivered its first pair of T901 turboshaft engines to Sikorsky. The manufacturer will integrate them into the UH-60M Black Hawk. Helicopters equipped with T901 engines will have 50% more power with better fuel efficiency, delivering longer range than today’s Black Hawks. First flight is planned for 2025. The T901 will eventually power the AH-64 Apache as well.
GE recently announced a collaboration with Airbus to develop a new clean-sheet turboshaft engine for helicopters. It announced no details about the engine, save to say they aim to produce one “that sets new standards in efficiency, reliability, and environmental responsibility.” This is a new relationship for the firms. To date, Airbus has shunned GE engines in favor of Safran and Pratt & Whitney Canada (P&WC). It is currently the only helicopter company that does not offer GE powerplants in any of its models.
GE has also completed another series of tests on its XA100 variable-cycle engine, and built the XA102 – a second adaptive engine which is an upgrade based on test results from the XA100.
However, last spring, the US Air Force’s $4-billion Adaptive Engine Transition Program (AETP) had just gone belly up. As a consolation prize, GE and other companies received 10-year contracts capped at $975 million to develop powerplants for the Next Generation Air Dominance (NGAD) fighter. It was originally scheduled to begin replacing US Air Force Lockheed Martin F-22 Raptors before 2030, but now this program too is in flux, with design requirements and due date suddenly in doubt.
One issue is cost. Pentagon officials estimate that the NGAD aircraft will cost 3 times the $110- to $136-million price tag of the Lockheed Martin F-35 Lightning II. US Air Force Secretary Frank Kendall says that cutting that expense is one of several issues under discussion. Others include integrating the aircraft with drone wingmen, redesigning it to use a single cost-effective engine instead of 2 expensive ones, and even leaving any human crew on the ground.
All this has GE and its competitors wondering how to proceed. The US Air Force is hammering out its fiscal year 2026 budget, which should bring at least some clarification.
Work continues on NASA’s HyTEC (Hybrid Thermally Efficient Core) program, which is now solely in GE’s hands. Phase 1 developed the high-pressure turbine, compressor, and power extraction components for the small-diameter core. Phase 2 will polish the design for a core demonstrator test, including the use of 100% SAF later in this decade.
The end product is destined for use in the RISE (Revolutionary Innovation for Sustainable Engines) open-fan engine being spearheaded by CFM Intl – GE’s 50/50 collaboration with Safran.
Pratt & Whitney Canada
P&WC has good news to report. Inevitably, one of its engines will propel the new Piper M700 Fury – the 700-hp PT6A-52. Also, a variant of the company’s 1000-shp PW210 turboshaft engine has been chosen to replace the Safran Arriel 2E powerplants formerly spinning the generators of the Airbus Helicopters PioneerLab hybrid electric demonstrator aircraft.
P&W’s PW1000G-series geared turbofans are having issues with parts fabricated from powdered metal between late 2015 and mid-2021, which were contaminated by impurities that have caused cracking in some high-pressure turbine and compressor discs, affecting Airbus A320neos and A220s, as well as in Embraer E-Jet E2s.
In April, FAA issued its 3rd order related to the problem. It required operators of affected PW1000G engines to take their aircraft out of service, inspect the engines for cracks, and accelerate replacement of turbine and compressor hubs, blade retaining plates, and hot-section seals.
More than 600 aircraft were grounded that month. Early estimates suggested airlines could lose more than $150 million to downtime and repairs. Ultra-low-cost carrier Wizz Air, whose headquarters are in Hungary, said aircraft could be out of service for up to 300 days, not counting expected parts shortages. Many operators want compensation from P&W.
Like GE, P&W has been elbows-deep in work on an adaptive engine for the NGAD. Similarly, it has been left hanging by indecision from the US Air Force. This likely has some impact on P&W’s little 150-lb-thrust TJ-150 engine, currently marketed for drones and missiles. However, P&W has been eyeing a possible market in the USAF’s Collaborative Combat Aircraft. This too is now up in the air.
Much of P&W’s R&D work is going into its F135 Engine Core Upgrade – the more conventional, non-adaptive engine that has replaced the XA100 and XA101 as the next powerplant for the F-35. Unlike the adaptive models, it will fit into an unaltered F-35B vertical takeoff and landing (VTOL) variant. Based on the existing F135 turbofan architecture, it will deliver 5% more thrust, improved fuel burn, and a 50% increase in bleed air cooling capacity.
Where development and refit of F-35s with adaptive engines was expected to cost around $6 billion, P&W’s contract to supply 250 upgraded engines for the F-35 runs a little less than $4.4 billion, not counting life cycle costs. The company plans to have engines in the field by 2029.
Rolls-Royce
R-R has been working to correct durability issues for customers using the Trent XWB-97 and Trent 1000 engines in widebodies operating from dry and dusty environments. The solution was a replacement blade for the high-pressure turbine. It carries a new coating expected to double the time-on-wing of engines used by Emirates Airline and other users based in the Middle East. It should even increase up-time by 50% in benign environments. Parts and labor shortages are expected to stretch the upgrade program into 2026.
Last year, R-R halted UltraFan testing, waiting for a customer who needed an engine that big. The company has now revived the test program and could partner with Airbus, which may offer the UltraFan for the next-generation A320 as a 3rd option, along with P&W and CFM engines. The aircraft is scheduled to fly in the 2030s.
R-R has also begun development of a scaled-down UltraFan demonstrator for narrow-body aircraft. Reportedly, Airbus is considering it for future single-aisle airliners, and both Embraer and Boeing have tentative plans for new models that may use such an engine. After focusing on widebodies for years, the manufacturer has had nothing in this market to compete with CFM and P&W.
Honeywell Aerospace
It has been a while since Honeywell introduced a new engine, and the company is rather close-mouthed about its turbine R&D. But here is what we know. After 4 years in service, the F124/F125 engines (with afterburner) reached their first 1 million flight hours last December. They are used in a number of jet trainers, light attack aircraft, and unmanned vehicles, and the company continues to work to improve the engines. Some of that effort could feed back to the civilian TFE731 turbofan, which served as the basis for the military models.
In its other specialty, Honeywell leads Project OperA, for “Operate Anywhere,” and Project DARWIN, for “Digital Assistants for Reducing Workload and INcreasing collaboration.” OperA aims to upgrade the European ATC system to accommodate air taxis and cross-border drone cargo deliveries, while DARWIN focuses on AI-powered digital assistants for human pilots.
Honeywell is also putting a good deal of effort into its ASCEND project – a collaboration with ARPA-E and the University of Maryland – to develop electrical propulsion systems improving on its 1-MW generator for the Flying Whale dirigible. Focal points for R&D include standard edge-wound windings, high-temperature insulation, air-cooled thermal management systems, and high-voltage power electronics.
Safran
The company has a new engine in the works – a turboshaft intended to replace its venerable Arriel for single-engine rotorcraft. According to Safran Helicopter Engines CEO Cédric Goubet, the program is protected by a confidentiality agreement, so few details have been released. He does say that they’re aiming for a 15–20% improvement in fuel efficiency.
Goubet adds that Safran is working on an 800-hp turbogenerator for urban air mobility aircraft. The generator is supplied by sister company Safran Electrical & Power. The combination has already been chosen to drive Electra Aero’s 8-prop blown-wing Goldfinch short takeoff and landing (STOL) airplane.
Safran is also completing work on the 1000-shp Arriel 2K, planned for Leonardo’s upcoming AW09 light single. The aircraft was originally designed around the Honeywell HTS900 powerplant.
In more immediate news, on July 2, a pair of Safran’s 2500-shp Aneto-1X turbines spinning the company’s own high-voltage DC generator drove the Airbus Racer compound helicopter to a speed of 227 kts – 7 kts above its design cruise. During cruise flight, 1 of the Aneto-1X engines can be turned off, cutting CO2 emissions radically.
In another effort to decarbonize aviation, Safran is working with Turbotech to modify that company’s 125-shp TP-R90 turbine to power light aircraft with hydrogen. This work seems likely to migrate up the power scale in a few years to business turboprops, as Daher is one of the program’s collaborators.
CFM International
CFM has not introduced any new engines of late. Then, it has little need to. Its CFM56-5B powers some 60% of Airbus A320-family aircraft now flying or on order. More than 15,000 CFM56-7B engines have been delivered to power Boeing 737 aircraft, and it is the exclusive choice for the Boeing Next-Generation single-aisle airliner. Some 5000 of its LEAP engines are in the air, and CFM has a backlog of 10,000 orders.
Building on that base, CFM is focusing its R&D on the RISE open-fan powerplant under development for parent companies GE Aerospace and Safran. The RISE program aims to cut fuel consumption and emissions 20% below those of its clean LEAP engines while burning nothing but sustainable aviation fuel.
This past July at the Farnborough International Airshow, the company announced completion of 200-plus hours of wind-tunnel testing with a 1/5-scale model. Testing included fan aerodynamics and acoustics, mounting on an Airbus wing section, and a high-speed, low-pressure turbine with advanced blades. The program has now moved on to advanced materials and new compressor, combustor, and high-pressure turbine technologies.
CFM still expects to carry out full-scale engine tests around mid-decade and have airliners flying with RISE engines by the mid-2030s.
The company is also working with Airbus to test hydrogen propulsion on a modified A380 within the next year or so. This will be a step toward development of a hydrogen-powered airliner capable of carrying about 200 people 2000 nm. Target date for the aircraft is 2035.
Owen Davies is a veteran freelance writer specializing in technology. He has been a futurist at Forecasting International and TechCast Global.