The new version of the Pratt & Whitney Geared Turbofan engine, the GTF Advantage, has been designed with the popular Airbus A321LR and XLR in mind. The engine maker has no plans to offer the updated version on the other aircraft models that are powered by the GTF, the A220, Embraer E2-family, or the Irkut MC-21, although it doesn’t rule out that some improvements might spill into these models. GTF Advantage made for the Airbus A321XLR. P&W presented the Advantage during a live and virtual event at its East Hartford Customer Training Center on December 2. The current version of the GTF, which has a gearbox for the fan to optimize its speed, has been developed since 2008 and entered commercial service in January 2016 with Lufthansa. Its early years have been marred with some well-published technical issues. Various redesigns and updates have produced a stable, efficient, and reliable engine that has delivered on the improvements it promised. The base GTF has an on average 16 percent better fuel consumption than previous generation engines. On the Embraer E2-series and the Airbus A220, the fuel burn is even between 19 and 22 percent better. Dispatch reliability is now 99.97 percent and over ten million flight hours are done. Getting more air through the engine Pratt & Whitney has been working on various improvements since 2016 and has specifically looked at the compact core, where it identified potential gains early on. This has resulted in changes to the internal airflow, the core, materials, and performance, for which P&W worked in close cooperation with its German partner MTU Aero Engines. “The GTF Advantage is providing more flexibility to our customers by providing higher thrust, lower fuel-burn, and lower temperatures for more durability”, said Senior Vice President GTF Tom Pelland. “Getting all three of those things at once in a product evolution is very difficult. If we had had a traditional, two-spool engine, you wouldn’t have been able to do what we have managed.” “We get more flow down the core. We really supercharged the engine through the low-pressure compressor. In driving more air down the core and in effect changing the way the air is going, we were able to bring in computational fluid dynamics or toolsets to optimize the compressor blades and the turbines for maximum efficiency”, says Geoff Hunt, Senior Vice President of Engineering. One area has been the high-pressure compressor (HPC). “With the HPC, the focus is on further improving efficiency, which makes a noteworthy contribution to reducing the specific fuel consumption and above all, lowering temperatures in the hot section,” says Dr. Stefan Weber, Senior Vice President Engineering and Technology at MTU in a media statement. “The design has also been made more resistant to damage in the area of the blisk rotors that can occur when the engine is in operation.” Another improvement is that on the high-speed low-pressure turbine (LPT), with better resistance to wear and a higher-performance active clearance control. Geoff Hunt: “We have had active clearance control before. This is the ability to pinch down the clearance between the turbine blades and the seals to get optimum performance, but here, we have really been to get an active system.” New coatings to improve blade durability A new generation of coatings for the turbine blades has been developed to increase thermal resistance and reduce erosion and dirt formation. Unexpected high wear, notably on engines operated by airlines in India’s polluted atmosphere, caused corrosion, resulting in the grounding of a large part of IndiGo’s and Go Air’s A320neo fleet between 2017 and 2019. Pratt worked on interim solutions but the new coatings should guarantee blade durability. As said, the Advantage will only be available on the Airbus A320neo family. Whereas the base GTF is offered with a power range of 24.000-33.000 pounds, the Advantage gets up to 34.000 pounds. “We spent a lot of time talking to Airbus about what this engine should be. It’s six years after entry into service. Customers and Airbus were very clear on higher thrust, more flexibility, and better performance at high altitudes. And to enable a product like the A321XLR to do transatlantic routes and fly to city pairs other airplanes can’t do”, said Pelland. The version for the XLR will be the PW1134GA/2-JM. He added that not everyone will need the higher 34.000 pounds thrust, “but the benefits will be there across the entire thrust range, including the higher thrust for the A321LR and XLR." At sea level, four percent more thrust is available, and in hot and high environments eight percent over the base GTF. “When you think of Mexico City, where the extra thrust can offer a 700 nautical miles range benefit at a high-altitude airport, opening up more city pairs and flexibility for our customers.” P&W expects to keep its 42 market share and 47 percent delivery share it has on the A320neo program now compared to the CFM LEAP. The GTF Advantage has been test flown since spring 2021. (P&W) Eleven engines available for testing Rig tests of the Advantage started in 2020, with Hunt saying that the program has run really smoothly from the start and produced the expected results. The first flight tests followed on the Boeing 747 flying testbed this March, after which the Advantage was checked for structural integrity. “We are now in our third round of durability and endurance tests but this will not be the last round”, Hunt said. There are eleven engines available for testing and durability tests, which will continue in the next couple of years until certification in 2023 and entry into service in 2024. They have done some 1.000 flight hours on the 747 testbed, but will fly early on the Airbus testbed as well. Early next year, the Advantage will start testing with sustainable aviation fuels. The Advantage is interchangeable with the base GTF as it uses the same aircraft interface. It can even use a mix of a base GTF and the Advantage on the same aircraft thanks to software options. “Interchangeability is so important for a seamless usage for the customer”, said Geoff Hunt. From entry into service in 2024, the Advantage will be prepared for 100 percent sustainable aviation fuels (SAFs) as P&W is fully committed to reducing carbon emissions of its engines. Without the GTF, the engine maker would not be able to deliver on this sustainability strategy, Pelland stressed. P&W and Embraer will start flight testing pure SAF on an E195-E2 early in 2022, they announced earlier this week. But before aviation will have 100 percent SAF, it will take time to get the specifications of the fuel ready, thinks Hunt, probably not before the back half of this decade. “In the meantime, it is incumbent on us to be testing and proof that our engines whatever specs SAFs will be.” Pratt's technology roadmap includes hydrogen During the presentation, Pratt & Whitney walked through its technological roadmap for the next decades and what it expects will be the most important developments. Hunt referred to improving fan efficiency to be able to run it slower and at the same time increase the size and by-pass ratio of the engine. More improvements on the high-pressure turbine are also on their way, running the engine hotter. But both developments wouldn’t be possible without improvements in advanced materials, said Hunt, like ceramic matrix composites. Pratt & Whitney Canada launched the new PW127XT at the Dubai Airshow, offering a three percent fuel burn over the previous PW120-series turboprop engines. The next step is the 2 megaWatt hyrbid-electric engine that was announced this summer that will be flight-tested on a De Havilland Canada Dash 8-300 by 2024. President Maria Della Posta said that various steps have been taken in selecting partners for the program. She is positive that the technology that comes out of the program will find its way into a later version of the GTF, where an electric motor could fit in to help drive the fan. Hydrogen is certainly another topic on P&W’s sustainability roadmap, although it will need further development of engine components. “We need to understand materials, we need to understand combustion systems, actuation systems. That’s the gaseous hydrogen. When you look at liquid hydrogen, that really doesn’t change much on the engine level but there will be challenges on the airplane level”, said Geoff Hunt. The real challenges will be to safeguard that it is green hydrogen, produced from sustainable energy sources, plus how to get the hydrogen at scale at airports and onto the aircraft. There needs to be collaboration across the industry, but P&W is in no doubt that hydrogen will find its way onto a GTF offspring in the next decade.
