The Gulfstream Way

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Dan Nale, Gulfstream Senior Vice President, Programs, Engineering and Test, and Scott McElvaine VP PW800 Program, provide an insiders’ view on the all-new G500 and G600 jets

The industry is keenly anticipating Gulfstream’s new G500 and G600, representing new generation jets with increased range at reduced fuel burn. The programme has involved extensive ground and air testing, the OEM investing massively in labs commissioned specifically for G500/600 development and system trials. The G500 had been scheduled for certification and first customer delivery in late 2017, but at October’s NBAA, Gulfstream announced a minor delay, for all the right reasons.

​Dan Nale, Gulfstream Senior Vice President, Programs, Engineering and Test, explains: “The G500 and G600 exceed the originally announced range capabilities. As a result, new certification test points are required and we anticipate G500 certification in early 2018, with customer deliveries following.”

​The revised range figures add 600nm to the G500’s capability at Mach 0.9, while the G600 adds 300nm at the same speed. In real terms, the additional range opens up significant city pairs. Nale says: “Now the G600 can fly from Hong Kong to London, New York to Beijing, Singapore to London, and Rome to Mexico City. The G500 has the range to reach from London to Los Angeles, Seoul to Los Angeles, Amsterdam to Johannesburg, and Rio de Janeiro to Paris.”

​So how was the excess performance recognised and what are the certification ramifications of the additional range? Nale reports: “Rigour and discipline are the core tenets of Gulfstream’s development and flight-test programmes. During flight testing, we discovered that both aircraft have margin beyond our original projections and we’ve been able to give some of that margin to customers while still adhering to the design requirements. At this point in the flight-test programme we’re confident in the G500 range and comfortable with the increased range we’ve projected for the G600.​

“The additional range results from this rigour and discipline, and the margins we calculated into the aircraft design.” There is also an inescapable correlation between engine choice and fuel efficiency, so how does Nale rate the G500/600 propulsion system? “Pratt & Whitney Canada is providing the integrated powerplant system, consisting of the engine, nacelle and thrust reverser, and it’s performing very well. Combined with the Gulfstream-designed wing, the PW800-series engines result in greater fuel efficiency, performance and speed. The speed capabilities alone offer significant time savings for customers, a longer duration between scheduled maintenance visits and lower accumulated flight hours.”


EVA asked Scott McElvaine, VP PW800 Program, how important the Pratt & Whitney Canada powerplant was in achieving the additional G500/600 range. “It’s difficult for me to respond, because there’s so much that goes into range, of which the powerplant is a big part. But there are aircraft aerodynamics, fuel and lots more to the equation. I can say that we think the PW800 represents the latest, greatest and best in class and, depending on your reference point, our fuel burn is about 10% better than the current generation of engines in our class too.”

It’s not the most straightforward response… So when Gulfstream announced the additional range, did it bring a big smile to his face? “Of course! Anytime they get up and talk about their aircraft, whether they refer to powerplant or not, it’s a pleasure, because it’s a real honour and privilege for us to be on the programme. We have a duty to deliver what we promised to the market and we take it very seriously.”

Wearing the PurePower label of Pratt & Whitney’s PW1000-series commercial geared turbofans, the PW800 was developed specifically for the G500 and G600. In its former application, designated PW814GA, it delivers 15,144lb thrust and as the PW815GA it develops 15,680lb for the G600. PurePower it may be, but the PW800 isn’t a geared turbofan.

​“It’s a traditional direct-drive engine because a geared turbofan functions well at around 30,000ft, but a bizjet engine operates mostly around the 45,000 to 51,000ft altitude, where big, slow-turning turbofans are not at all helpful to propulsive efficiency. We call it PurePower because it shares common core technology with the PW1500G used on the Bombardier C Series airliner, from the high-pressure compressor, through the combustor to the high-pressure turbine. Those parts are very deep inside the engine – I consider them its beating heart and lungs – so nothing you see when you look at the complete engine is common to the PW1500G.”

​That common technology means parts of the PW800 could, theoretically, be swapped for those of the PW1500G. More realistically, it means G500/600 customers will benefit from Pratt &Whitney Canada’s experience with PW1500G cores accumulating thousands of hours on the gradually expanding C Series fleet. It’s perhaps an unexpected benefit to an outsider, but nowhere near as surprising as the difference McElvaine explains between the two PW800 variants.

​“After production, each PW800 is given a certificate effectively saying it’s a good engine, along with a serial number. They’re all born identical through supply and production, but at the point of certification they become either 814 or 815. The software within the FADEC [full authority digital engine control] understands which variant the engine is and what its ratings are. Thereafter, it remains either an 814 or 815, the two aren’t interchangeable in the aftermarket.”

​The concept that the software decides the engine’s rating and subvariant is somewhat abstract, but McElvaine simplifies the notion: “Imagine you have a car engine that’s good for 200mph, then consider that it’s restricted to 150mph. It’s the same engine, just restricted. So the higher thrust PW815 runs at the higher temperatures and pressures required by the G600’s mission. It’s akin to describing the 814 as a derated 815.”

Testing, testing

Much of test programme has seen the two models trialled in parallel, with specific work targeting their differences. With the G500 nearing certification, Nale looks back on a test campaign that began long before the type’s 2015 first flight. “Bolstered early on by extensive lab testing in our advanced research and development facility in Savannah, the G500 and G600 flight-test programmes are going extremely well. More than 70,000 hours of ground testing has been completed and we’re seeing the results in how reliably the aircraft have been performing.

“On the G500 programme, the five flying aircraft have achieved more than 1,000 flights and 3,700 hours of testing. They’ve reached a maximum speed of Mach 0.995 and an altitude of 53,000ft. En route to NBAA-BACE in October, the production aircraft set a city-pair record and flew its longest sector to date, from London to Las Vegas, in 10 hours 19 minutes, demonstrating the increased range announced at the show.

​“G500 flight trials accomplishments include the completion of initial handling qualities testing and field, climb and low-speed performance testing. Steep-approach development in support of post-type certificate testing is also complete, as are water ingestion tests, with many others under way in support of certification. Feedback from both programmes suggests the aircraft have excellent handling qualities and are performing as expected, or better than expected in terms of range.

​“The first flight of the G600 last December was definitely a flight test high point. In addition to taking place on 17 December, the anniversary of the Wright Brothers’ first flight, the chaseplane for the G600 was the first G500 production aircraft. The G500’s excellence in providing chase can be attributed to its remarkable handling qualities – the smooth flying facilitated by the active-control sidesticks made it easy for the pilots to fly in formation.”

​The G600 was always scheduled to debut after its smaller sibling, but Nale notes: “The aircraft’s testing is being conducted at the same time as the G500’s and we expect certification later in 2018. The fully outfitted production aircraft, the fifth test aircraft, made its first flight in August and debuted at NBAA-BACE, completing the trip from Savannah to Las Vegas with ease. The five aircraft have accumulated more than 230 flights and 1,000 hours of flight testing, reaching a maximum altitude of 52,000ft and a top speed of Mach 0.999. The G600’s longest flight to date is 13 hours 5 minutes.

​“Initial envelope expansion and flying qualities testing is complete, as are flight controls development testing, loads flight testing and low-speed and field-performance development testing. G600 static test, conducted on full-size structural test articles in our structural lab facilities, is also complete. Of course the larger wingspan, longer cabin and increased thrust of the G600 require separate flight trials. That said, with the commonalities between the G500 and G600 flight deck and avionics, we’re applying much of what we’re learning on the G500 to the G600.”

For its part, Scott McElvaine says Pratt & Whitney Canada has completed around 17,000 hours of PW800 test and a similar number of cycles. “I worked on the Citation Columbus project, so I was there at the very beginning of the PW800 development process. I calculated then that we’d run about 10,000 hours of testing and everybody thought I was crazy. I responded – ‘Watch us!’ So we’ve put a lot of effort into proving the maturity and reliability we aimed to achieve.

​“Subsequently, we’ll work very closely with the fleet lead customers to ensure we’re appropriately monitoring usage and powerplant performance over time. We expect certain things to happen and want to make sure we stay in line with those expectations, as well as detecting any anomalies so that we can take the correct proactive action. In parallel, we’ll continue our own test programme looking for product improvements and specific parameters we want to follow up on if we see an in-service experience that tweaks our curiosity.

“The technology suite we’re deploying across all our engines enables us to gather data, but for this programme we’re collaborating with Gulfstream to leverage their data transmission system such that we simplify the way we integrate into the airplane. It doesn’t matter to me how I get the data, what matters is using it appropriately to get the high level of performance we’re looking for, from the product and from a service viewpoint. That service includes the all-inclusive ESP PW800 PurePower pay-per-hour programme.”

Cabin Comfort

Gulfstream has also invested heavily in the G500/600 cabin, expending many of its 70,000 hours of ground trials on getting the cabin right and making sure it works, and continues to work, as advertised. The interior of the company’s G500 demonstrator exemplifies the work, but how close is it to a customer aircraft? Nale reckons: “The design of the first demonstrator reflects extensive feedback from our Advanced Technology Customer Advisory Team [ATCAT] and Customer Advisory Board, who help us fine tune and finesse each and every element of the overall cabin, from the fridge to the floor and everything in between. That input is a result of our significant efforts to include the customer’s voice in every aspect of aircraft design. Initial customer deliveries, meanwhile, are collaborations with our customers, who work with our skilled team of interior designers to create a look that reflects their personal tastes.”

​Its labs, including a Cabin Integration Test Facility, part of a larger Integration Test Facility (ITF), have enabled flight crews much enhanced access to G500/600 systems than would have been the case with demonstrators alone.

​The result is a range of cabin options, all of them having run the gamut of a test campaign peopled by folk with experience garnered through everyday operations. Now those options are available to customers, Nale says Gulfstream offers extensive help to ensure they make the right decisions for their needs. “To help establish starting points for visualising cabin interiors, our interior design and advanced computing technology teams have worked together to use virtual and augmented reality tools to complement the personal attention customers receive during the outfitting selection process. They can experience the cabin flexibility immediately, evaluating floor-plan configurations and material options in a virtual environment.”

​He’s predictably confident about how passengers will receive the new cabins; but it’s a confidence based on hours of testing and unlikely to be misplaced. Nale says: “The cabin environment on the G500 and G600 features technological advances similar to those we’ve applied on the G650 and G650ER, and they’re proving just as effective. That technology results in some of the industry’s most comfortable cabins, with exceedingly low sound levels, low cabin altitudes and 100% fresh air. It means passengers benefit from reduced fatigue and better rest, especially on the long-distance journeys these aircraft can accommodate.”

​It’s a fine picture of an impressive aircraft, but Gulfstream has every intention of moving the G500/600 cabin along as new opportunities and technologies emerge: “Continuous improvement is among our guiding forces and we’re always looking to innovate for our customers. Members of our design team work closely with our research and development engineers to offer customers the latest in cabin comfort, customisation and technology.”

Sitting At The Front

Gulfstream has apparently skimped on nothing to ensure passenger comfort, but what of the cockpit? Technological advances aside, if a cockpit doesn’t please pilots, they’re unlikely to provide a favourable input to purchasing discussions. According to Nale: “As we anticipated, we’re hearing that the G500 and G600 are ‘pilots’ aircraft’, with an extremely intuitive flight deck. Pilots adapt to the active-control sidesticks, touchscreens and additional technology advancements quickly, and many have wondered how they ever flew any other way. We invested heavily in research and development to ensure the technology was ready before integrating it into our Symmetry Flight Deck. As a result, the flying experience has been going very well.”

​And with first G500 delivery scheduled for early 2018, is a Gulfstream pilot training programme up and running? “FlightSafety is Gulfstream’s factory-authorised training provider for the G500 and G600; their first flight simulator was installed at the Savannah Learning Center in 2014, even before the G500’s first flight,” Nale confirms. Meanwhile, maintenance training has been facilitated through Gulfstream Product Support maintenance technicians embedded with the G500 and G600 flight-test teams.

​“They’ve been collaborating to gain experience working with the aircraft, ensuring components are easy to access and maintain, and preparing for a smooth entry into service with training, publications, maintenance procedures and parts. It all enhances the support provided when aircraft are delivered to customers. And with the flight test programme progressing so well, we also recently launched the Customer Advisory Board [CAB] for the G500 and G600. ATCAT and CAB include a range of operator roles, from pilots and flight attendants to maintenance crews.”

​Dan Nale is perhaps more intimately involved in the G500/600 programme than any other individual. Has it become the weekly grind, or does its potential still excite and fascinate him? “We’re seeing strong interest from customers around the world and it’s exciting to see our investment coming to fruition for customers. We’re doing what we said we would do, when we said we would do it and we’re exceeding the already impressive performance capabilities we announced. This is the Gulfstream way, and it’s what sets us apart.”