GE's ATP Engine Becomes Catalyst

With the unveiling of the official name of the Advanced Turboprop engine as the Catalyst in March, GE Aviation celebrated 10 years in the business and general aviation (B&GA) turboprop sector and its substantial progress toward becoming a provider of a suite of engines reaching up to 1,700 shp.

GE jumped into the B&GA turboprop market sector through its 2008 acquisition of the former Walter Engines line of turboprops, providing the foundation for the light turboprop market with engines ranging from 750 shp to 850 shp. That acquisition gave GE Aviation a foothold in the already developed Czech Republic manufacturing sector, a built-in customer base, and knowledge of the types of services necessary for such engines, said Brad Mottier, v-p and general manager of GE Aviation’s Business and General Aviation and Integrated Systems division.

But as important to GE, the former Walter family, now known as the H-Series, has provided “domain expertise” that has helped pave the way for a clean-sheet design turboprop family to pit against the venerable Pratt & Whitney Canada PT6 series.

GE announced that 900- to 1,700-shp turboprop family in 2015 originally as the Advanced Turboprop (ATP) line. And with that announcement, GE had its first major win: a contract to power Cessna’s new single-turboprop Denali.

Mottier revealed the change in the name from the ATP to the Catalyst in Prague two months ago, saying it signifies GE’s newest turboprop engine family is “a catalyst for change, it’s a catalyst for the competition to be working on something else….it’s a catalyst for new airframe designs..for new maintenance...for new operations...for better pilot experience…[and] for better service.”

Emphasizing that the engine is not intended only to provide a means to go faster or be more fuel efficient, Mottier said it is designed to change the pilot experience to more of a “jet like” environment. This includes a simplified cockpit, thanks to the single-lever engine and propeller Fadec control. Calling the engine a digital design from birth, he added the Catalyst family also will pull down from GE’s commercial family the “digital twin” concept, which moves toward on-condition maintenance capabilities, with the ability to track exact flying conditions, from weather and flying environment to how the engine is flown on every flight and marry that data with built-in knowledge of the “DNA” of each engine.

The engine will initially enter service with a 4,000-hour time-between-overhaul period, up to a 33 percent increase from similar engines in the class. Even so, GE Aviation’s long-term goal is to eliminate service bulletins and unnecessary inspections by knowing the specific operating conditions of each Catalyst engine under the digital twin concept.

“We believe it’s a new standard,” he said. In fact, the engine has so much new technology and simplification in operation that it will require new-cockpit redesigns in forward-fit applications.

At the same time though, Mottier believes there is not as much risk with this program since “we are bringing technologies that have millions, hundreds of millions of flight hours in GE commercial [applications] and applying it into the small engine space.”

With a 16:1 pressure ratio, the Catalyst will provide up to 20 percent lower fuel burn and 10 percent higher cruise power than its competitors, says GE. The engine is designed with variable stator vanes to optimize performance throughout the envelope and a two-stage cooled high-pressure turbine that enables the engine run much higher firing temperatures than other engines in the class. The engine further has a three-stage counter-rotating low-pressure turbine designed to minimize turning “losses” and improve overall efficiency.

While the three-stage low-pressure turbine design builds in extra weight, GE Aviation believes the additional available energy, power, and efficiency produced through the design more than makes up the difference.

GE is incorporating additive manufacturing (3D printing) with a dozen key parts that will lower the parts count by 855, reduce weight by 10 percent, and help provide a 1 percent improvement in specific fuel consumption.

The single-lever control is designed to simplify pilot workload, and the Fadec manages the operability throughout the envelope, said Gordie Follin, engineering lead for the Catalyst program, noting, “You don’t have to think about it.”

“It frees the pilot to fly the airplane…[and] greatly simplifies what’s happening. It will be automated as you go through taxi, climb, cruise, the whole cycle,” added Paul Corkery, the lead of turboprop programs. Further, the control provides built-in safety, preventing over-speed, over-temperature or over-torque conditions.

The formal naming of the Catalyst comes as GE Aviation has moved into the testing phase of the engine program, completing first run for the first model—a 1,240-shp variant for the Cessna Denali—in December. The engine had accrued close to 40 hours of testing at GE’s test cell, before moving to a new test cell as part of a collaboration with a Czech Technical University team (CVUT) in Prague. Tests were expected to restart last month under the partnership with CVUT, which will be testing that engine over the next several years for health-engine monitoring.

The next engine—referred to as number 5—is anticipated to be ready for testing soon. That engine, to be used for altitude testing, is slated to head to Canada this summer for trials. Meanwhile, three engines will go to Cessna beginning later this year in preparation for the Denali's planned maiden flight in first-quarter 2019.

In all, GE Aviation expects the program to encompass 10 engines, including one that will be flown on a King Air testbed, again through its partnership with CVUT.

The Catalyst will come under new ice crystal test requirements, which Fallin said he believes marks a first for a new engine program. While the regulations were intended for larger commercial engines, the requirements affect all new types. “The consequences for these small engines are much more than for a big engine,” he said. “We are pioneering a new validation methodology with the FAA.”

In total, the test program is anticipated to span some 2,000 hours by the time the Cessna Denali enters service in 2020. The engine will be built at B&GA’s turboprop headquarters in Prague under an EASA production certificate, but certified under the FAA through an agreement involving GE Aviation, the FAA, and EASA.

While work continues on the first Catalyst application, Mottier noted, “We’re already working on additional applications and additional engines and engine models.” Next application announcements will be at the discretion of the customer, but he indicated a belief that announcements may be forthcoming in the next couple of years.

GE Aviation has internally forecast a market for some 300 Catalysts a year over the next 20 years, but Mottier qualified that to point out how long the P&WC PT6 has been on the market and the thousands of engines produced over the years.

While the Catalyst program represents a significant investment for GE Aviation and ramps up in Prague, it expands on the manufacturing capabilities already in place through the H-Series.

H Series

In fact, while assembly lines will be separate, component manufacturing between the ATP and H-Series will be co-located. The plant, which includes four test cells in addition to component manufacturing and engine assembly lines, represents a dramatic transformation from its state when GE first moved in a decade ago.

After GE Aviation acquired the Walter lines, it was forced to move production into a different facility in Prague, because the original property had been sold to a separate entity. It found a rundown factory in Prague that was complete with vegetation growing inside.

That factory underwent a renovation. But to keep the Walter production certificate, the company transferred the equipment to the new location in such a way that it was an exact replication of the original facility, “right down to the placement of the workbenches,” Mottier said.

Since then, GE Aviation has continually improved those facilities, introducing lean concepts and upgraded facilities and processes. And it built up manufacturing capabilities since that time, expanding the workforce in Prague by 60 percent.

For the H-Series alone, GE Aviation has poured $55 million into upgrades, beginning with the compressor and swapping out less environmentally friendly aspects of the engine before turning to other aspects such as the gearbox. The company added 20 percent more power and improved fuel burn by 10 percent over the original Walter M601.

And although the H-Series provided GE Aviation with an entry into the B&GA turboprop market and provided that much-desired domain expertise, the series also has provided a steady flow of business, with the 300th engine delivered last year (an H80-200). The series has had more than a dozen applications and work continues on new variants. Testing is beginning on an aerobatic variant of the H75 for the new Diamond Dart military trainer, while the new Let 410NG is coming to market with the H85. Meanwhile, Thrush is closing in on certification of GE Aviation’s electronic engine and propeller control (EEPC) system on the H80 powering the 510G agricultural airplane. The EEPC already had been approved for H75 engines powering the Nextant G90XT King Air upgrade.

In all, GE Aviation has invested $400 million in its turboprop programs and expanded its engineering staff to more than 1,800, a three-fold increase. Its supply chain spend has doubled and is expected to increase six-fold over the next 10 years, Mottier reported.

In reflecting over the B&GA business that GE Aviation has built over the past decade, he traced from the beginnings of a dilapidated factory that has become an expansive operation in the Czech Republic, fed by local university collaboration and talent, and of what once was a faltering engine line that is now a thriving business of engine families spanning from 750 shp to 1,700 shp. “It’s been an incredible journey over the past 10 years,” he said.