NBAA Convention News

Engine Programs

 - October 13, 2010, 6:57 AM

Business jet engine programs this year seem to be moving slowly, with little progress to report. Some–like the Snecma Silvercrest–have not been officially launched yet and are still looking for an application. Most news comes from derivative engine programs at Honeywell, Pratt & Whitney Canada and Williams International. Research programs–such as Rolls-Royce’s E3E core continue and the FAA is funding an effort called Continuous Lower Energy, Emissions and Noise (Cleen), while GE Aviation and Honeywell are making new engine upgrades available for in-service aircraft.

GE Aviation

GE Aviation (Booth No. 1747) confirmed that it is working on a new 10,000-pound-thrust engine. According to a GE spokeswoman, the engine manufacturer is in discussions with airframers about new engine applications in this thrust class. “Derived from the TechX development program, this completely new engine in the 10,000- to 20,000-pound-thrust class is aimed at the larger cabin aircraft and includes advanced technology from existing programs as well as new core technology based on the core being used in the new CFM LEAP-X engine for narrowbody aircraft.”

GE Aviation is offering a simplified modernization program for some CF34 engines to upgrade them, on-wing, to an on-condition maintenance standard. The simplified upgrade is available for 36 CF34-3A2 engines on Bombardier Challenger 601 business jets. These engines meet the criteria to go from a hard-time maintenance schedule to on-condition service.

According to GE, the upgraded engines will have longer time on wing and reduced maintenance costs. No more hot-section inspection or overhaul will be scheduled. All CF34-1As and -3As, as well as -3A2s with a serial number older than 350-490, can be upgraded, too, but with a shop visit for some hardware changes.

“For serial numbers from 350-490 to 350-525, we verify that the configuration is consistent with the service bulletin requirements,” Bill Hoernschemeyer, GE Aviation’s general manager for corporate aviation sales, told AIN. There is no hardware change in the on-wing upgrade, he clarified.

GE Honda Aero

The GE Honda HF120, which is to power two delayed aircraft programs–Honda Aircraft’s HondaJet and Spectrum Aeronautical’s Freedom S.40–is progressing in its test program. Since May, GE Honda engineers have performed hailstorm testing. Nine engines are dedicated to certification testing. Two more engines are dedicated to engineering validation.

Last May, certification of the HF120 was delayed once more. It is now pegged for the second half of 2011. The HondaJet is now slated for certification in the third quarter of 2012.

The 2,095-pound engine features a wide-chord, compound-swept front fan and a two-stage booster. The single-stage compressor is made of a high-temperature titanium impeller “for maximum engine pressure ratio and stall-free performance,” according to GE Honda (Booth No. 1547). The combustor is in a reverse-flow configuration, with single-stage air-blast fuel nozzles. The high-pressure turbine has one stage, while the low-pressure turbine has two. The high-pressure and low-pressure spools are counter rotating. The bypass ratio stands at 2.9. As for maintenance, the company is pledging a 5,000-hour time between overhaul. By the time it enters service, the HF120 should have logged 15,000 cycles.

Honeywell Engines

Honeywell’s 7,445-pound-thrust HTF7250G is progressing toward certification late this year. The engine is powering the in-flight-test Gulfstream G250. “A slate of design validation and certification tests have been completed,” a Honeywell spokesperson told AIN. These tests were for cooling (for the turbine section), vibration (for engine externals) and controls. It also is conducting software certification tests and operability flight tests (for surge and stall margins). The company also plans to conduct inclement weather testing and the 150-hour endurance test.

Honeywell (Booth No. 6600) is still targeting 2011 for the certification of the HTF7500E but program managers “have to make up time in the program to hit the target certification date,” the spokesperson said. The 7,000-pound-class engine, which is to power the Embraer Legacy 450 and 500, ran for the first time in July.

This first run had been planned for April but was delayed until “receipt of engine hardware for testing.” Since then the engine has run on the ground and in flight on the ­company’s Boeing 757. “We tested performance–fuel efficiency, windmill start envelope and so forth–and operability, including surge and stall margins,” the spokesperson explained. He added that engineers are satisfied with the results.
The HTF7500E has a 34.2-inch fan and a bypass ratio of 4.2. The compressor has five stages (four axial and one centrifugal), while the high-pressure and low-pressure turbines have two and three stages, respectively. The Legacy 450 and the Legacy 500 will share the same hardware. Honeywell promises it will be offered with an on-condition maintenance program from its entry into service.

Honeywell is also supplying the TFE731-50R engines on the Hawker 800XPR retrofit that Hawker Beechcraft has started offering for the 800XP.  The engine is already in service on the Hawker 900XP. It will deliver 4,660 pounds of thrust on the 800XPR. The improvement is in temperature margins. According to Honeywell, the updated engine will give the aircraft a 7-percent range improvement for ISA-condition takeoffs. Moreover, it will “yield up to a 24-percent range improvement for hot-and-high takeoffs.” The engine maker also pledges lower operating costs. The original Hawker 800XP is powered by a pair of TFE731-5BRs.

Honeywell will also incorporate technology from its Saber 1 engine improvement program into HTF7000 production engines. Those same improvements will appear in the HTF7250G and HTF7500. Certification tests are under way for the updated HTF7000. According to Honeywell, Saber 1 combustor technology will meet all ICAO standards, with a 25-percent reduction in nitrogen oxides (NOx) emissions.
The company has also launched Saber 2, which is expected to reduce NOx emissions by another 25 percent. The new Tech 7000 technology demonstrator makes use of a fleet of HTF7000s to develop Saber 2 as well as make other improvements “in a relevant environment.” Full component-level testing has already begun and combustion systems are running.

Other improvements to the HTF7000 will affect the fan, compressor and turbines. Among the goals are better power-to-weight ratio, a smaller core to reduce engine weight and a higher pressure ratio for improved fuel burn.

Pratt & Whitney Canada

Pratt & Whitney Canada (PWC, Booth No. 2704) is developing the 6,100-pound-thrust PW307B for the Learjet 85. The engine features PWC’s Talon advanced combustor technology, which is claimed to outperform ICAO standards by more than 30 percent for NOx missions. The engine also will meet Zurich 5 requirements for zero noise surcharge fees (Zurich Airport in Switzerland has special noise rules).
The PW307B is currently in the detailed design phase. It is on schedule to make its first run in the fourth quarter of this year, a PWC spokesperson told AIN. FAA certification should happen in the fourth quarter of 2012.

The PW307B is built on the same turbomachinery as other PW307s. Changes include engine control software and “minor additions on the aft bypass duct and the fuel motive system flow.” The PW307A powers the Falcon 7X trijet, while the PW307C powers the Falcon 2000DX twinjet.

Although the PW810 program was halted shortly after the Cessna Citation Columbus program was terminated last year, Pratt & Whitney Canada is keeping an eye on the market for the PW800 family. It would use the same core engine as
the PW1000G geared turbofan, which will power next-generation regional jets, and would be aimed at large and ultra-long range business jets, supplying 10,000 to 20,000 pounds of thrust.

Sister company Pratt & Whitney, based in East Hartford, Ct., last summer completed testing on the full-scale PurePower engine core with 260 test hours. It validated performance and operability goals, Pratt & Whitney said. The PurePower PW800 engine pledges double-digit improvements in fuel burn, environmental emissions, engine noise and operating costs.


As of early this month, Rolls-Royce (Booth No. 4267) had a piece of news to report in its business jet engine programs. The AE 3007A2, which powers the Embraer Legacy 650, received certification from Brazil’s ANAC civil aviation authority. The 9,440-pound-thrust engine received FAA certification in April.

More powerful than the Legacy 600’s variant, which stood at 7,953 pounds, the AE 3007A2 contributes to the 500-nm range extension to 3,900 nm. The pair of AE 3007A2s allows more fuel to be carried and their specific fuel consumption is lower, according to Rolls-Royce. The Legacy 650 is to enter service by the end of the year.
Engine development testing of the AE 3007A2 is complete, and four engines are participating in flight tests on two Legacy 650s. Compared to its predecessor, the AE 3007A2 provides 6 to 12 percent higher thrust at takeoff and climb, according to the manufacturer’s numbers. The new version features an “advanced” wide-chord fan and updated software, both of which cut fuel burn at long-range cruise speed.


Despite still lacking a launch customer, Snecma of France continues to develop its Silvercrest business jet engine. Targeted at large and/or long-range business jets, it could provide 9,500 to 12,000 pounds of thrust.

Snecma (Booth No. 3865) claims its first business aviation design will offer a 15-percent fuel burn improvement. NOx emissions are expected to be 50 percent below current CAEP 6 requirements. Noise is said to be 20 dB below Stage 4. The Silvercrest’s core engine completed an 80-hour test campaign in 2008.

Williams International

The Williams International  FJ44-4–the engine that powers Cessna’s new CJ4–was certified in February. The FJ44-3AP is in the certification process, earmarked for Hawker Beechcraft’s Premier II, the Nextant ­re-engined Diamond/Beechjet 400 and the PiperJet single. Also going through the certification process is the FJ33-5, intended for the much-delayed Cirrus SF50 Vision and Diamond D-Jet.

Last summer Williams International (Booth No. 5149) told AIN that, since the FJ44-1A went into production in 1998, it has been improving engine efficiency on the FJ44 by about one percent per year. All Williams engines are said to fall into the zero emissions surcharges category at Zurich Airport.

Cleen Engine Program

Last June, the FAA awarded a total of $125 million to Boeing, General Electric, Honeywell, Pratt & Whitney and Rolls-Royce-North America to participate in the Continuous Lower Energy, Emissions and Noise (Cleen) program. A significant part of the amount will be spent on engine technologies that will find applications in business aviation. Under a cost-sharing arrangement, each company will match or exceed the FAA’s contribution, thus bringing the overall total value of the program to more than $250 million.

The Cleen program targets 2015 for these technologies to enter into service. The goals of these research and development efforts include a 33-percent cut in fuel burn and a reduction of NOx emissions by 60 percent. Cumulative aircraft noise levels should be cut by 32 decibels.

Under the aforementioned agreement, GE has signed a $66 million contract with the FAA. The company sees the money going primarily toward its lean-burn/low-emissions Taps II combustor. Taps II is at the center of GE’s eCore hot section, and the company began testing it in June 2009. Taps II also will be at the heart of partner CFM International’s Leap-X engine for single-aisle airliners as well as the company’s next generation of regional and business jet engines.

The eCore demonstrator ran last year and this year with a single-stage turbine. Testing of the second eCore demonstrator, with the 10-stage compressor but a two-stage turbine, is scheduled to begin next year. Once the architecture is chosen (between the single-stage turbine and the two-stage turbine), GE expects the new core will provide up to 16 percent better fuel efficiency than the best it has in service today.

Honeywell’s contract is for a total of $27 million over five years. The effort will focus on fuel-burn reduction and alternative fuels. The engine maker will use its TECH7000 turbofan test engine as the basis for its research. Using this HTF7000-based demonstrator, ­engineers will focus on engine cycle ­efficiency through increased operating pressure and turbine inlet temperature.

In biofuels, Honeywell’s subsidiary UOP has developed technology to convert sources like algae and camelina into aviation fuel. Trademarked “Honeywell Green Jet Fuel,” it is said to meet all specifications for jet fuel. “It offers significant savings in greenhouse gas emissions,” said Ron Rich, Honeywell’s vice president for propulsion systems. To evaluate the use of aviation biofuels, Honeywell and UOP will work with Gulfstream and the Massachusetts Institute of Technology.

Rolls-Royce, which has received $16 million, will perform engine demonstrations focused on reduced fuel burn and alternative fuels. Engineers will look for ways to reduce turbine cooling airflow, which should yield gains in cycle efficiency.

In biofuels, Rolls-Royce will work with Cessna to test an AE 3007 engine on a Citation X, including component, engine, rig and flight testing. The company’s aim is to assess fuel suitability, environmental sustainability and industrial and commercial viability. Rolls-Royce also wants to “build on fundamental scientific understanding,” it said.

For the longer term, Rolls-Royce has a research program under way for two-shaft engines in the 16,000- to 25,000-pound-thrust range. In business aviation, this addresses the top of the market–large-cabin, long-range twinjets. The program also applies to narrowbody airliners.

The research effort, dubbed E3E for “efficiency, environment, economy,” is being conducted at Rolls-Royce’s German design offices and factory in Berlin. The latest core engine build, 3/2b, was tested from March to May, running 40 hours at Stuttgart University’s altitude test facility.

E3E is aiming for a 15-percent reduction in fuel burn over in-service engines, which would translate into a 15-percent cut in CO2 emissions. Thanks to a lean-burn combustor, E3E has already demonstrated NOx emissions at 45 percent of CAEP 6 standards.

Tests included altitude relight for the lean-burn combustor, which was deemed successful, with relight capability up to 36,000 feet. Also tested was the new shroudless turbine And a new system for blade tip clearance control was checked. Component efficiency was measured at sea level and 35,000 feet.

At the heart of Rolls-Royce’s research core is a nine-stage, high-loading high-pressure compressor (HPC), which provides a pressure ratio of 22:1. E3E program chief engineer Holger Klinger pointed out to AIN that in-service V2500s (found on some Airbus ACJs) need another stage of high-pressure compressor and an additional four-stage low-pressure compressor (booster) to reach a comparable pressure ratio. Therefore, the E3E compressor has 1,000 fewer airfoils than a V2500 in its compression stages. Moreover, six compressor stages are blade-integrated disks (blisks). The bottom line should be a lighter, more compact and cheaper engine. The thrust-to-weight ratio should be improved by 25 percent And unit cost cut by 30 percent.

For high-pressure ­turbine blades, design engineers managed to find new 3D aerodynamic shapes that enable a reduction in the number of blades. However, the greater distance between the blades makes it impractical to keep shrouds at the tips because they would be too large to withstand stress and temperature, Klinger explained.

This then called for finding another way to manage tip clearance. As a solution, Rolls-Royce designed an abradable ceramic liner for the inner case. The tips of the blades are coated to make them abrasive, yielding a rub-in tip clearance control system. “To test this, you need a full engine running environment, otherwise you get wrong results in terms of abradability and cycle life,” Klinger said.

Some E3E technologies have already been infused into some Rolls-Royce engines. The Gulfstream G650’s BR725, for example, has light titanium blisks in its high-pressure compressor. Again in the compressor, elliptical blade leading edges reduce profile losses.

Two core engines have run since 2008. “We are currently preparing core 3/2c, with an improved abradable turbine liner,” Klinger said. In 2012, 3/2d will run with an enhanced lean-burn combustor for lower emissions and better efficiency. Later, core 3/3 will be fitted with minimal instrumentation, which will enable it to perform 1,200 cycles in a cyclic endurance test.