More power, lower fuel consumption, and safer/simpler operations: These are only some of the advances being achieved in helicopter engine technology today. In fact, there is so much amazing progress being made that we’re cutting this introduction short – to get straight to the cool stuff.
Honeywell Runs with the HTS900
Builder of legacy helicopter turbine engines such as the T53 (used on the Bell UH-1 Huey) and the LTS101 (Bell 222 and Airbus Helicopters H125), Honeywell Aerospace is now forging ahead with its new HTS900 turboshaft engine. The HTS900 incorporates improvements gleaned from Honeywell’s joint projects with the U.S. government. Its mission is to be a turbine engine that is more powerful and fuel-efficient than older engine models; all within a compressor architecture that has room for future upgrades.
One improvement found in the HTS900 is the engine’s twin centrifugal compressor, which came out of Honeywell’s small heavy fuel engine project. “The twin centrifugal compressor technology gives us an 11:1 pressure ratio in the compressor, which delivers great fuel economy,” said Doug Kult, Honeywell’s retiring product line director for light helicopter turboshaft engines.
Another HTS900 advance is the engine’s ported shroud. Designed to prevent compressor surges, the ported shroud uses a combination of shape and holes to guide airflow into the engine; eliminating the use of moving inlet guide vanes or flow fences. “This is a Honeywell-patented device that is completely passive; there’s no moving parts,” said Kult. “We’ve eliminated all the maintenance cost associated with those accessories.”
A third advance in the HTS900 is the engine’s use of a ‘segmented shroud’ around the HST900's high-pressure turbine, to minimize gases leaking from the powerplant and thus not being available as a source of power. “This shroud actually grows and shrinks with the high-pressure turbine as it heats up and cools down,” said Kult. “We manage that clearance down to a few thousandths of an inch.”
Factor in the HST900's use of FADEC (full authority digital engine control) to allow the engine to be managed by computer rather than the pilot, and this powerplant is a substantial step forward for Honeywell Aerospace.
The HTS900 is currently being used in Kopter (formerly Marenco) Helicopters’ clean sheet Kopter SH09 single-engine helicopter. It is also being retrofitted into Bell 407 helicopters under the Eagle 407HP engine upgrade program.
Lycoming Adapts Fixed-Wing Engine for Helicopters
Lycoming Engines provides the majority of certificated piston power plants used in helicopters; such as the range of engines used on the Robinson R22 and R44, the Guimbal Cabri G2, Enstrom F-28/280, and other type rotorcraft.
Building on this base, Lycoming Engines recently certified a variant of its 390 Series fixed-wing engines for helicopter use. The new HIO-390 is a rotorcraft version of the four-cylinder IO-390 engine, producing 210 hp at 2,700 RPM. The HIO-390 will be used on the Enstrom TH180 currently under certification. The TH180 is a two-seater training helicopter, designed to provide flight schools with a roomy, low-maintenance rotorcraft trainer.
Lycoming has also been highly active on 100LL alternative fuels, directly approving unleaded options on many engine models as these fuels become available.
Pratt & Whitney Canada Moves Ahead with the PW210
To date, Pratt & Whitney Canada (P&WC) has built over 16,150 helicopter engines, with more than 9,550 in service today powering more than 4,800 helicopters. “Our helicopter engines have a proven track record and reliability better than the most stringent ETOPS (extended-range, twin-engine operational performance standards) requirements,” said Nicolas Chabée, vice president of sales and marketing for P&WC Helicopter Engines. “The past seven years alone have seen four major new helicopter engine certifications: The PW210S (Sikorsky S-76D), PW210A (AW169), the PT6C-67A (AW609) and PT6C-67E (H175).”
Chabée cites the PW210, P&WC's newest 1,000 shaft horsepower class engine, as the company’s most advanced helicopter powerplant to date. “The PW210 has what's known as variable geometry vanes at the engine inlet that can be adjusted for maximum performance to accommodate the demands on the engine at any given moment,” he said. “You can liken it to creating a big engine at takeoff and a smaller engine once it's in flight.”
The PW210 incorporates P&WC’s unique mixed flow rotor, “which allows us to generate more power from the engine with no weight impact, providing better payload and range,” said Chabée. “The PW210 engine also represents step changes in fuel consumption and power-to-weight ratio.”
As for the future? “We are currently demonstrating a new 2,000 shp engine with a particular focus on operability and acceleration for turboshaft applications,” Chabée said. “The power availability on this new engine will be virtually instant and in OEI (one engine inoperative) situations the active engine will take over so seamlessly and rapidly that there will be minimal altitude loss.”
The Rolls-Royce M250 helicopter engine is an industry stalwart. It has logged more than 250 million hours of operation, while being upgraded on a regular basis to deliver better performance and fuel economy for operators. “Nearly 33,000 M250 engines have been delivered, with approximately 16,000 in operation around the world,” said Jason Propes, senior vice president for Rolls-Royce Helicopters & Light Turboprops.
When it comes to advancing the performance and quality of its rotorcraft engines, Rolls-Royce is pursuing design improvements in both electrical and digital technology. “On the electrical side, we are working on both incremental improvements to current engines; such as more electrical power available on existing airframes, or bigger step change in areas such as new hybrid electrical propulsion system,” Propes said. “Electric propulsion benefits include more efficiency and capability, while lowering emissions and maintenance costs.”
“On the digital side, Rolls-Royce is already very advanced in the collection and analysis of data on our large civil engines, and recently launched our ‘IntelligentEngine’ program and R2 Data Labs to accelerate our efforts in those areas,” said Propes. Meanwhile, “In our light helicopter business, we have just launched another variant of our new M250-C47E engine, this one for the new Bell 407GXi that was announced at Heli-Expo.” The C47E engine includes a new, state-of-the-art dual-channel FADEC (full authority digital engine control) system to reduce the pilot’s workload while providing system controls redundancy for safety enhancement.
This engine manufacturer is also exploring ways to use the digital data collected by its M250 Series IV engines to help fleet operators maintain and run their rotorcraft more effectively, reliably, and economically.
Safran Pushes the Envelope
Best known for their installation in Airbus Helicopters, Safran Helicopter Engines are also used by Bell Helicopters in its new Bell 505 light (Arrius 2R engine) and Leonardo’s AW189K medium (Aneto-1K) rotorcraft.
The 2,500-3,000+ shp Aneto is one of the company’s “three new-generation turbines,” said Bruno Bellanger, Safran Helicopter Engines’ executive vice president of programs. The other two are the Arrano (1,100-1,300 shp) and the Ardiden (1,400-2,000 shp). “We unveiled our new Aneto high power engine family last October,” Bellanger said. “Designed for super-medium and heavy helicopters, it features several models ranging from 2,500 to over 3,000 shp output.”
This engine manufacturer expects the AW189K’s Aneto-1K engine to be EASA-certified by the end of 2018. During HAI Heli-Expo 2018, the Aneto-1X was selected to power the Airbus Helicopters Racer demonstrator. This is a ‘clean sheet’ high-speed rotorcraft that is expected to achieve a 400 kph airspeed.
Including its three new-generation engines, Safran is spending about 15 percent of its revenues on R&D. “Our plan is to keep improving our gas turbines with new materials and components, to develop new concepts such as hybridization (gas turbine/electric engine) combinations, and new maintenance services,” Bellanger said. “One major goal is to reduce the cost of owning an engine by improving its fuel consumption.”
Safran is also increasing its use of 3D printing in metal – which it refers to as “additive manufacturing” – to build engine components. “We started working on this technology more than 10 years ago, and three SLM (selective laser melting) printers are now in service in our Bordes plant,” said Bellanger. “Using these techniques since 2015, we have been serial-producing components for Arrano (fuel injector nozzles) and Ardiden 3 (combustors/swirlers) engines using SLM techniques. Our new Aneto also features parts made in this way and deployments will continue across our product range.”
Hybridization is another big theme for Safran Helicopter Engines; namely using a combination of thermal and electrical power sources. “We do not anticipate 100 percent fully electric architecture for missions of 30 minutes or longer,” Bellanger said. “Our studies show that battery energy will remain 10 times lower than fuel-powered turbine, during the next 15 to 20 years.”
Safran’s first hybrid engine combo is known as the Power Pack Eco Mode concept. Due to be tested on the twin-engine Airbus Helicopters Racer, the Power Pack Eco Mode configuration allows a pilot to ‘pause’ one engine while in cruise, resulting in fuel savings up to 15 percent. When the second gas turbine engine is required for acceleration, landing, or autorotation, an onboard electric motor will bring the turbine up to full power rapidly.