Thierry Dubois is a freelance writer specializing in helicopters, business aviation and aerospace technology. He earned a degree in fluid dynamics from an engineering school in Toulouse, France in the mid-1990s. At an unexpected crossroads, he found his first job in journalism. In 1997, he started working for French aerospace weekly Air &amp; Cosmos in Paris. This lasted until 2000, when he moved south to Lyons. He then became a freelancer, working for various aerospace publications and has been part of the AIN team since late 2000. In addition to writing about business aviation, Thierry shares responsibility for the rotorcraft section. He also is a regular on-site writer for AIN’s daily editions at international airshows such as the Paris, Farnborough, Dubai and Singapore shows, as well as at EBACE in Geneva.
In 2007, he won the Honeywell award for “Best systems or technology submission” at the Aerospace journalist of the year awards. In 2013, he won an Aerospace Media Award for the "Best Safety, Training &amp; Simulation Submission."
In other activities, Thierry moderates international conferences on aviation technology topics. Thierry is married and has three children, who seem to begin enjoying the mountains–as their parents do.

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Thierry Dubois

The number of engines known to be in the design or development phase is relatively low, compared to what it used to be a few years ago. Several engine manufacturers are therefore redeploying their efforts to incremental improvements and, for the longer term, research or demonstration programs. Currently in the certification testing phase are GE's Passport, Snecma's Silvercrest and Williams International's FJ33-5 and FJ44-4A-QPM.

 


GE Aviation

 


The GE Passport program has logged 7,800 hours of engine testing, representing 2,100 cycles, Shawn O'Day, GE Aviation's senior vice president for business and general aviation, told AIN. The 16,500-lb-thrust engine is in the middle of ground endurance testing. The final big hurdle, as O'Day put it, will be the fan blade-out test in the first quarter of next year.

 


Asked how the two-year delay for the Global 7000/8000 is impacting the Passport program, he explained that GE (Booth N2304) has not changed its schedule. “We are running our tests how we committed we would do, pursuing certification as planned,” he said. GE has delivered two flight-test engines to Bombardier, which has installed them on a Global 7000 prototype.

 


“We might want to sell the Passport to anybody else who may need it,” O'Day added.

 


GE’s 9,220-lb-thrust CF34-3B MTO, a new evolution of the CF-34-3B, is set to enter into service by year-end on the Bombardier Challenger 650. It has 5 percent more takeoff thrust than the CF34-3B on the 605. The additional thrust is pilot-selectable with a new performance thrust setting.

 


The GE Honda Aero Engines joint venture company in March received its production certificate for the 2,095-lb-thrust HF120. The new turbofan is to power the Hondajet, which was awarded provisional certification by the FAA in March. The HF120 has also been selected as a retrofit engine for the Sierra Industries Sapphire upgrade program for legacy Cessna CitationJet platforms.

 


With the H series turboprops (750 to 850 shp), GE has been selected on 10 applications. “We think we can make a big impact on the turboprop market,” O'Day said. An electronic engine control unit (EECU) has recently finished ground testing on a Nextant G90XT, a remanufactured King Air C90, which is equipped with H75 engines. The EECU cuts pilot workload, as it enables single-lever power control.

 


What about a more powerful version of the H series? “I'd be lying if I said we want to stop here,” O'Day answered. The 1,200- to 2,000-shp bracket is where GE sees demand. A new center of excellence for turboprops at a still-to-be-determined location Europe will be “a key piece of the story,” O'Day went on.

 


For future engines, GE has no demonstrators, but does have conceptual studies. “We still have things to explore to improve specific fuel consumption [SFC], etc.” O'Day said. He emphasized that a technology has to buy its way into a program; no ceramic-matrix composite (CMC) can be found on the Passport, for instance. But with so many technologies in the portfolio, “you can pick and choose,” O'Day pointed out, referring to development work on the GE3000 military turboshaft. The T700 replacement is aimed at enhancing the rotorcraft’s power-to-weight ratio by more than 60 percent.

 


Snecma

 


As of mid-October, the Dassault Falcon 5X still had to make its maiden flight with its pair of 11,450-lb-thrust Snecma Silvercrests. Certification target for the Snecma (Booth N5317) Silvercrest remains in the first half of 2016, despite the fact that Snecma is having to resolve slight deformation of the engine casing that occured during high temperature testing. The French engine maker is developing a modification to remedy this issue, which has delayed the first flight of the 5X.

 


Williams International

 


Williams International (Booth C8125) vice president of business development Matt Huff told AIN the 1,800-lb-thrust FJ33-5 is “in the final steps of certification.” It is planned to be completed over the next few months, in time to support deliveries of the Cirrus SF50 single-engine jet in 2016. Last spring, FJ33-5 engine certification was slated for August 2015.

 


Flight testing of the 3,435-lb-thrust FJ44-4A-QPM on the Pilatus PC-24 is “progressing very well,” which will lead to engine certification next year, according to Huff.

 


Honeywell

 


Honeywell’s (Booth C7807) HTF7000 family production line is now running at a quick pace, senior technical sales manager Mike Bevans told AIN. The FAA has certified Embraer’s Legacy 450, on top of the other applications for the HFT7000 series engine, including the Legacy 500, Bombardier Challenger 300/350 and the Gulfstream G280.

 


Upgraded versions may well be launched in the near term, AIN understands. Super-midsize and midsize jets are working well for charter and fractional-ownership companies and airframers are therefore looking at that market segment. “’How can we help them get a bit more speed or a bit more range, still climbing direct to FL410?’ I answer questions [like these] all the time,” Bevans said.

 


Honeywell is participating in the second phase of the FAA's Continuous Lower Energy, Emissions and Noise (CLEEN II) program. Funding is shared with the FAA on a 50-50 basis. “We are doing things with high-temperature turbine seals and low thermal conductivity coatings for the high-pressure turbine [HPT],” Bevans said. A new nickel-based superalloy, called Alloy 10, is being used for the disk of the HPT's second stage. “This is the most hostile environment in the engine in terms of heat, speed and load,” Bevans stressed. Blade tip clearance is another area of work in the turbine to improve the engine's power-to-weight ratio.

 


Honeywell looks to ceramic matrix composites (CMCs)–not currently used on Honeywell engines–in hopes of lowering weight. Parts are being tested at full size for tolerance and durability. CMCs can be used only in static components, such as the exhaust system gas path. They are suitable for hot-section components that are not heavily loaded and have a simple geometry, Bevans explained. At technology readiness level 5 to 6, they are thought not to be mature for production yet.

 


For the fan, Honeywell did consider a blisk some 10 years ago. But design engineers were thought maintainability issues were too great. A fan blisk of that diameter could not have been inspected with fluorescent techniques at maintenance workshops, as the required equipment installed at that time would not have accommodated such a large part. And the techniques to repair damage to the blades were not sufficiently mature, Bevans added.

 


Bevans also emphasized his team is working on reduced emissions for engines below the 6,000-lb-thrust threshold, even though they are not subject to pollutant regulations, based on requests from airframers and operators. One reason may be that some airports levy fees that depend on the emission level “but it's more about being a good citizen,” Bevans said.

 


The original design of some of Honeywell’s current turbofans is four decades old. The company is trying to apply low-emission technology into these turbofans, such as the 5,000-lb-thrust-class TFE731. Engineers are constrained by the physical geometry of the combustor but can work with techniques like coating, effusion cooling, etc.

 


On the 1,650-shp TPE331 turboprop, Honeywell is looking at a new engine control system. It has been hydromechanical so far “and we are receiving some requests about Fadec or electronic control,” Bevans said. He made it clear the company is not committed to go ahead yet, as it would involve extensive development. “We have an EECU on the Reaper UAV but it is not certifiable,” he said.

 


Rolls-Royce

 


Rolls-Royce (Booth C8134) is planning to add an automatic data download feature on the 13,850-lb-thrust Tay and 15,000-lb-thrust-class BR710 turbofans that power the Gulfstream G450 and G550, respectively as well as in-production Bombardier Globals (BR710). The new function is already in place on the 16,900-lb-thrust BR725 for the G650. “It improves predictive maintenance, as data is downloaded daily, as opposed to monthly when it is done manually,” a spokesman told AIN. The company expects to be “even more proactive in identifying and resolving issues,” thus increasing operational availability. It is simultaneously enhancing its algorithms for engine health monitoring.

 


Meanwhile, Rolls-Royce has demonstrator engines for large commercial aircraft applications running on test stands, but is hoping to scale down some technologies for business aviation. A geared fan, for instance, could thus be in the cards, AIN understands. “We are looking at all engine architectures for business aircraft,” the spokesman said.

 


Pratt &amp; Whitney Canada

 


Pratt &amp; Whitney Canada (Booth C10807) in February hit a major milestone, when the 15,144-lb-thrust PW814GA and 15,680-lb-thrust PW815GA engines received Transport Canada certification. The PW814GA then powered the maiden flight of Gulfstream’s new G500 business jet in May.

 


The PW800 family has achieved more than 4,000 hours of evaluation operation and more than 8,200 cycles. This includes more than 110 flights and 600 flight test hours on Pratt’s Boeing 747SP flying testbed. In total, the advanced common core technology, used in six PurePower engine applications, has amassed more than 22,000 testing hours. The technology is used in Pratt &amp; Whitney's PurePower geared turbofans for commercial aircraft.

 


The company is soon to announce the ESP PurePower PW800 service plan. “Pratt &amp; Whitney Canada is looking at about a dozen new things to cover and is in discussions with key customers as it continues to craft its offering,” a spokesperson said. Among other things to be included are proactive engine health monitoring, actionable diagnostics, borescope picture evaluation, training and technical publications.

 


 The 5,760-lb-thrust PW306D1, selected to power the Cessna Citation Latitude, received FAA approval in February. Rated at a maximum takeoff thrust of 5,907 pounds, this latest addition to the PW300 engine family features higher thrust at climb and cruise as well as improvements in overall SFC (specific fuel consumption). In addition, the PW306D’s engine control system is integrated with the Latitude’s avionics and autothrottle system, to make operation easier. In May, the 6,725-lb-thrust PW307D, set to power Dassault's new Falcon 8X, was granted Transport Canada certification. The Falcon 8X had successfully completed its first flight in February.

 


For the 950- to 1,780-lb-thrust PW600 engine family, Pratt “continues to make the necessary investments,” although light jets continue to be adversely affected by the world economic downturn. “Customers in this market segment are taking a ‘wait and see’ approach,” the spokesperson said. Asked what will be the next development in the 2,900- to 4,500-lb-thrust PW500 family, she said, “it is too early to comment on this.” On the PT6A turboprop, a Fadec is being considered for some versions. This would help improve SFC and reduce pilot workload. Today's maximum power in the PT6A family is close to 1,700 shp.

Engine Makers Tackle Incremental Improvements

GE, Snecma and Williams are the only manufacturers known to have engines currently in development.

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