In a business aircraft market that has seen a spate of new programmes, they are the power behind the flown. The industry’s five main turbojet manufacturers have been busy of late, with Safran aiming to deliver its delayed Silvercrest – chosen for the Cessna Citation Hemisphere and Dassault’s Falcon 5X – by early next year, and new powerplants from General Electric and Pratt & Whitney Canada undergoing flight test campaigns on, respectively, the latest large-cabin Bombardier Global and Gulfstream types.
Meanwhile, the third Cessna Citation Longitude prototype – powered by the Honeywell HTF7700, a variation on the US company’s HTF7000 family – has taken to the air, with the aircraft due for certification at the end of this year. Not to be outdone, Rolls-Royce – rejected by long-time customer Gulfstream when the Savannah-based company opted for P&WC on its G500 and G600 – is developing a new engine core based on the Advance and UltraFan technologies it is developing for large commercial airliners. It hopes the product will be available for future business jet programmes from 2020.
Bombardier’s Global 7000 – with its two 10,000-20,000lb (44-89kN)-thrust GE Aviation Passport engines – is well into flight testing and due to enter service in 2018. The aircraft has been flown at Mach 0.995, making it the largest business jet to come within five-thousandths of a Mach number below supersonic speed. The engines have completed 3,100h in ground and flight test, says Brad Mottier, GE Aviation’s vice president for business and general aviation, who adds that the Passport “continues to meet our expectations in preparation for entry into service”.
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The Passport features innovations such as a 52in (132cm)-diameter titanium fan blisk, the first application of this technology in an engine of this size, and a core scaled down from the Leap airliner engines produced by its CFM International 50/50 joint venture with Safran. The Global 7000 and yet-to-fly Global 8000 are the engine’s only applications so far, but Mottier says: “Although we don’t have anything to announce, we are talking to customers, looking to understand their development plans and how Passport fits into the picture.”
P&WC also says the two variants of its PW800, powering Gulfstream’s G500 and G600, are “performing very well”, with 13,000h of testing completed, including 3,500h on the aircraft. “It has been an amazing achievement,” says Scott McElvaine, vice president PW800 marketing and customer service. The engine, which is also the Canadian company’s first product in the 10,000lb-20,000lb-thrust segment, will be produced at Mirabel, alongside the PW1000G for the Bombardier CSeries, Embraer E2 and Mitsubishi Regional jet. “We are smack in the middle of ramp-up,” he says.
P&WC originally developed the PW800 for the Cessna Columbus before that programme was cancelled in 2009. However, one year later, the United Technologies subsidiary was quietly awarded the contract for Gulfstream’s newest pairing – although an announcement was not made for another four years when the jets were launched. Although the PW814, for the G500, and the G600’s PW815 are not P&WC’s first foray into the large-cabin segment – its 4,700lb-8,000lb-thrust PW300 powers the Dassault Falcon 7X and 8X trijets – they are its first products for a two-engined type.
For Honeywell, Dave Marinick, vice president aerospace aftermarket, says the HTF7700 “continues to operate flawlessly” on the three in-test Longitudes, “with excellent feedback from pilots on their performance”. Textron has become the fourth aircraft manufacturer to choose the 7,000lb-thrust HTF7000 engine family, alongside Bombardier for the Challenger 300 and 350, Gulfstream for the G280 and Embraer on the Legacy 450 and 500, arguably giving Honeywell a wider portfolio of customers than any other business aircraft engine manufacturer.
Safran, on the other hand, is a relatively new player in the segment, and, although it has notched two significant successes with the Hemisphere and Falcon 5X, its 10,000lb-12,000lb-thrust Silvercrest has not had an easy ride. Dassault in March said it had begun talks with Safran over compensation, after announcing early last year a near three-year delay for 5X entry into service, to 2020, which it blamed on problems with the engine. Dassault chief executive Eric Trappier said the hiatus had significantly impacted on its backlog and entailed additional development and engineering costs.
Safran says it is on track to certificate its redesigned powerplant early next year, with altitude tests “beginning soon” in Russia. In November, it claimed issues that caused the delay were “behind us”. These were traced to airflow through the engine not being “as controlled as the designers expected” – thought to be a side-effect of a decision to use an axial-centrifugal design for the high-pressure compressor. Active clearance controls were added to the low pressure turbine, and software controlling the engine hardware was adapted to maintain a steady airflow through the engine.
There was better news for Safran at last year’s NBAA show, when, despite its problems with the 8X engine, Textron announced the French manufacturer’s selection on the new large-cabin Hemisphere. The 4,500nm-range jet is due to fly in 2019 and enter service in 2020. The Silvercrest had originally been earmarked for the Longitude when it was introduced as a 4,000nm-range jet. However, when Textron reduced the Longitude’s range to 3,500nm, the Silvercrest was swapped for the lower-thrust Honeywell HTF7500.
Rolls-Royce is hoping that a new product – dubbed Advance 2 – could represent its revival in the business aviation market. Although the UK manufacturer powers several prestigious programmes, including the Gulfstream G650 with the BR725, it has not won a place on any in-development aircraft. The new core will comprise a 10-stage high-pressure compressor, combustor and two-stage high-pressure turbine, and form the basis of a new business jet engine family that will span a thrust range between 10,000lb and 20,000lb.
The thinking behind Advance 2 is that it could be scaled in conjunction with different low-pressure systems to create a range of propulsion options. At an event in Germany earlier this year, Rolls-Royce revealed some of its technical philosophy, with blisks rather than disks on the HP compressor and shroudless blades in the HP turbine. The fan rotor will be a blisk rather than being assembled from individual blades. New materials would allow the hot section to withstand higher temperatures. The company hopes to have a demonstrator engine available “relatively soon”.
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