Milestone moments: how the Trent XWB broke the long-haul record

Among the many certifications a new civil aviation engine must receive before it can be put to work, ETOPS (‘Extended Range Operation with Two-Engine Aircraft’) is one of the most pivotal.

An ETOPS rating certifies how long a twin-engine aircraft can safely operate with just one engine, which is the time it takes to reach the nearest diversionary airport. This limits which aircraft are allowed to fly over deserted areas and oceans, and for how long.

Basically, ETOPS is an imaginary tether tied around the aircraft that regulates where it can fly. For aircraft manufacturers, it has a big impact on how many planes they can sell – because an aircraft is only as good as where it can take you.

So, on October 30th, 2014, when a group of Rolls-Royce engineers gathered with representatives from airlines and airframe manufacturers to witness one part of the ETOPS certification test for a new engine, the Trent XWB, there was a buzz of excitement in the room.

“They were mostly our customer base, around 40 or so customers,” says Tim Boddy, Rolls-Royce’s Head of Marketing for the Trent XWB at the time.

To receive its paperwork for an ETOPS certification, Rolls-Royce must take an engine, then simulate over 3,000 flights on a testbed with each shaft in the engine ‘out-of-balance,’ so the engine and its components experience high vibrations and a far harsher ride than they will ever see in service. This unforgiving trial of endurance comes with an ETOPS diversion test every 1,000 cycles where the engine needs to demonstrate flawless operation. At the end of the test, Rolls-Royce has to completely disassemble the engine in question, piece by piece, and lay out all its 30,000 individual components across a table for independent inspection by the airworthiness authorities

It looked like the heaviest, hardest jigsaw puzzle to ever grace a flat surface.

During this initial stage of the ETOPS certification process, Rolls-Royce brought together a group of civil aviation experts to view the dissembled engine, which was put before them. They began walking the room, running their fingertips over every feature, every surface, slowly examining its many components. For the first time for many of them, the Trent XWB engine had hardened into something concrete, something real.

And now it was time to put it to the test. Would the Trent XWB measure up to their exacting standards? Could it achieve what no other engine had done before?

Trent XWB: in brief

Trent XWB engines on order worldwide: 1800+

Customers: 49

Maximum power at take-off: The Trent XWB-84 generates 84,173 lbf (374 kN force)

Fan: 118” diameter

Connecting faraway places: The Trent XWB powers the longest scheduled flight, spanning 15,345km flight from Changi, Singapore to Newark, USA.

Power packed into every blade: At take-off, each of the Trent XWB’s high-pressure turbine blades generate around 900 horsepower (per-blade), or about the same power produced by a Formula One racing car.

In high demand: Rolls-Royce delivers up to one Trent XWB every day of the week.

Flight hours: Over three million

Fuel savings: $2.9 million (per year, per aircraft)

For those unfamiliar with the civil aviation industry, generally speaking, one of the large airframe manufacturers, like Airbus or Boeing, will announce an aircraft they plan to build.

Its specifications include things like thrust capability, fuel burn and overall efficiency. And it’s down to the engine manufacturers to create something that fits within the prescribed parameters.

After an intense competition, Airbus selected Rolls-Royce as the sole engine supplier for all versions of the A350 XWB aircraft with a brand new engine, the Trent XWB.

Airbus and Rolls-Royce spent about five years refining the aircraft and engine design together to give maximum possible capability and efficiency. Once final designs had been agreed and the first engines manufactured, Rolls-Royce was ready to begin testing and, in June 2010, it was strapped to a stationary testbed for the first time.

More tinkering; more testing. Then, in February 2012, Airbus announced that the Trent XWB had successfully made its maiden flight aboard Airbus’s dedicated A380 flying testbed. (Learn more about Rolls-Royce’s own flying testbed, the Hefty Bee, here).

Its performance was everything that had been hoped for. The Trent XWB proved to be a powerful, reliable and efficient engine. But without an ETOPS certification, all its raw power would lay dormant.

Flying further without sacrificing efficiency

To receive an ETOPS certification demands a battery of tests. Once the ground tests were completed and passed, they needed repeating in flight.

ETOPs for an aircraft covers many systems, not just the engine. So Airbus ran a series of tests for the A350-900 to complete the final certification. For the engine that meant completing the single engine diversion for real, shutting down one engine while flying over the middle of an ocean, then completing the journey to a destination over six hours away.

Exactly how an engine performs under this scrutiny determines its ETOPS rating. If an aircraft is rated for ETOPS-180, for example, that means it’s certified to fly on just one engine for three hours – meaning its flight path must never take it more than three hours from the nearest airport.

Today, the best ETOPs certification record is 370 minutes, for the Airbus A350, powered exclusively by the Trent XWB. This maximum diversion time, of six hours and 10 minutes, is equivalent to a maximum diversion distance of 2,500 nautical miles (4,630 km), a civil aviation industry record.

Having such a generous ETOPS allowance passes on many benefits to airlines.

For one, aircraft making long-haul journeys aren’t forced to hug certain routes with diversionary airports along them, allowing them to fly a more direct path to their destination. It also helps to open up new routes – and all this added efficiency translates into faster flights, as well as lower fuel burn and costs.

Power of Trent

Efficiency. Value. Innovation.

Why ETOPS is a pivotal point in an engine programme

According to Boddy, after roughly 3,000 flight simulations the engine had performed exceedingly well and the authorities were happy.

But more importantly, what would the customer think, after waiting many years for the product to come to life?

For this, Rolls-Royce invited all the customers to Derby to find out and examine the multitude of parts laid on the table in front of them.

‘The ETOPS test itself is a pivotal point on the programme,” says Boddy.

“It’s where you go from being experimental to showcasing the actual production product – the engines customers will actually get to fly.”

Moreover, says Boddy, the ‘showcase’ portion described here is a special moment for all concerned.

“We got lots of positive feedback. We had Airbus, the airframer. We had airlines – which we call operators – like Qatar Airways, United Airlines, TAP Portugal, and US Airways. It’s a set of really rigorous and demanding customers.”

According to Boddy, the attendees were a little nervous to start with because they hadn’t necessarily seen the engine in detail at that point.

“I think it was relief because, until then, what they had seen from Rolls-Royce were mostly Powerpoint presentations. Impressive specifications and big promises, but nothing tangible (in a lot of cases, customers had bought the engine before we had built the thing). But then, after they finally saw it, saw what it could do, we had all these executives coming up to us, smiling, saying what a great day it was for the program.”

After nearly a decade of backbreaking work that went into developing this engine, all the thousands of hours and dozens and dozens of people involved, this was a special moment of satisfaction for Boddy.

But, he says, there’s another good reason for assembling so many stakeholders – the opportunity to tap into their knowledge.

“Because they’ve lived with engines so long – even if they weren’t Rolls-Royce engines. It’s a great opportunity to talk about the overall reliability and durability of components they were seeing for the first time,” says Boddy.

“They’d say, you know – ‘I have this problem with this kind of component. How have you solved this problem on the Trent XWB?’”

Boddy says this back-and-forth often teases out real insights and sparks new ideas. There’s no substitute for hearing it from the horse’s mouth.

“Really, at the end of the day, all this dialogue helps Rolls-Royce continually roll out improved products. And that’s what it’s all about.”

To find out about another tough test that Rolls-Royce puts its engines through, read about our cold weather testing here.

To learn more about the Trent family, visit our Power of Trent hub.

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