Farnborough Air Show

Rolls-Royce “pretty active” with Trent 7000

 - July 9, 2016, 12:01 AM
The latest EP3 version of the Rolls-Royce Trent 900 engine will enter service later this year when it powers the first of 52 remaining Airbus A380s for Emirates Airline, which has switched from the General Electric/Pratt & Whitney Engine Alliance GP7200 chosen for its first 90 such machines. Rolls-Royce says the powerplant has been achieving undisclosed performance targets.

Eight months after reaching the “first engine to test” stage last November and with two of four planned Rolls-Royce Trent 7000 (T7000) development units having run, the new exclusive powerplant for the re-engined Airbus A330 Neo represents “a pretty active program,” according to customer marketing head Peter Johnston.

Relative to its parent Trent 700 design, the 68,000 to 72,000-pounds-thrust T7000 has double the bypass ratio and 10-percent better specific fuel consumption, while creating 10dB less noise. It does this partly by drawing on Trent 1000-TEN architecture as well as technology from the Trent XWB.

Rolls-Royce (Hall 4 Stand B18) is incorporating a new electronic engine control unit, accessory-drive train/gearbox, air-start capability and related external changes, and is adapting the design to work with the new engine bleed-air system (EBAS). It will also have a new Aircelle nacelle.

Testing, including altitude, icing and operability checks, has already been completed on the first Trent 7000, dubbed L71/1 in its first iteration (but identified as engine serial number (ESN) 7001 when fully mounted in test beds). With engines not completed in numerical order, second development unit L73/1 also has completed its first runs and is being used for functional as well as operability tests.

In build last month (June) was the third example, L72/1, which is destined for systems performance and will be the formal type test unit, while the final development engine L74/1 is earmarked for cyclic and extended-range operations testing that simulates typical airline service. T7000 certification work is taking place throughout this year.

Simulated altitude testing, with particular attention to running in icing conditions, has been conducted with L71/1 in the U.S. at the Arnold Engineering Development Center C-2 test cell at Arnold Air Force Base in Tennessee. There, the engine completed four “air-on” days for icing, operability, performance and start/relight testing.

For anti-icing, the T7000 ducts intermediate-pressure compressor bleed air through the core-engine stator blades to protect the core and prevent “nick and ding” damage from detached ice particles, thus retaining performance and reducing maintenance requirements, according to Rolls-Royce.

The company claims that the T7000 will have unequaled high-temperature and high-altitude take-off and payload capability, significant margins over all current and future environmental rules, and similar pilot and operational practices to the T700. Common characteristics shared between the two models are designed to support operators with mixed fleets of A330s and re-engined A330neos, according to Johnston.

It is now about a year since the first T7000 parts, including combustion outer and inner cases and the intermediate casing, reached the manufacturer’s finished parts stores. Assembly took place during July-September last year as the complete 05 module was brought together with the compressor assembly and other major elements in the vertical module stack, which comprises the final stage, said Johnston.

With European Aviation Safety Agency airworthiness approval for the Boeing 777X’s Trent 1000-TEN “very close” (in June), some certification reports from that engine will contribute to T7000 type approval, according to Johnston. Rolls-Royce expects the new engine to be approved in the early part of 2017, as T7000 flight-testing gets under way. Delivery of the first production engine is expected in a little over 12 months’ time, ahead of entry into service that is scheduled for late 2017.

The T7000 incorporates as many T1000-TEN parts as possible, with necessary changes including the different EBAS requirement compared to the A330’s more conventional cabin systems. For this, the new engine will feature two new bleed outlets to supplement the inherited intermediate- and high-pressure compressor bleed ports, that help with surge margin control.

Johnston said that the T1000-TEN’s combustion-chamber outer casing and intermediate casing have been modified and the engine’s core externals re-dressed to accommodate the EBAS above the engine. Fan case and liner changes essentially relate to accommodating different Airbus design styles, compared with previous Boeing-oriented requirements.

The full-authority digital-engine control unit involves different software to interface with the A330’s systems, and the T7000 oil/air seal system is modified to suit the different operating conditions.

The engine manufacturer noted the industry trend toward larger fans and smaller engine cores, which by default has created capacity to mount line-replaceable units (LRUs) on the fan case. This not only positions the LRUs in a cooler environment but also makes them more accessible for maintenance.

The accessory gearbox, which constituted a major element of early T7000 development work, will be one of the first products from Aero Gearbox International, the Rolls-Royce joint venture set up with Safran subsidiary Hispano-Suiza less than two years ago to design, develop, produce and support accessory gearboxes for all future Rolls-Royce civil engines.

T7000 industrial ramp-up will benefit from the manufacturer’s investment in risk- and revenue-sharing partnerships and in additional production, test and overhaul capacity. While the first engines will be built at the company’s Derby headquarters in the UK, others will be assembled at its Seletar facility in Singapore.

A new testbed, suitable for this size of engine, has been built at Dahlewitz in Germany, where Rolls-Royce has set up a centre to conduct research and technology development for power gearboxes and related components. “The test-stand for gearbox development in Dahlewitz will be able to measure dozens of performance parameters per second,” said the company.

According to Airbus statistics at the beginning of June, Airbus has orders for 186 A330neos from Air Asia X, Delta Airlines, Garuda Indonesia, Hawaiian Airlines, TAP Portugal (which will be the launch operator), and TransAsia Airways, along with lessors Air Lease, Avolon, and CIT. There are also memoranda of understanding between Airbus and operators Arkia of Israel and Iran Air. o

BOX

Trent 900 on Track for A380 Service

Rolls-Royce (Chalet D3, Hall 4 Stand B18) says “initial indications” suggest the Trent 900 (T900) engine to power 52 remaining Airbus A380s for Emirates Airline has been achieving its (undisclosed) performance targets since it first ran in April.

The engine manufacturer has been particularly encouraged to win this new T900 customer, the Middle East carrier having previously selected the General Electric/Pratt & Whitney Engine Alliance GP7200 for its first 90 examples of the A380. Emirates is also keen to see a Rolls-Royce powerplant on any re-engined A380 Neo project, a program that Airbus continues to mull with no immediate plans to expedite.

The latest Enhanced Performance (EP) 3 production standard has involved “many small changes,” including improved aerodynamics (especially in the intermediate-pressure (IP) compressor), high-pressure turbine improvements and optimization of cooling air, according to customer marketing head Peter Johnston. Other areas of attention have been fan-blade elliptical leading edges, sealing in the IP and low-pressure (LP) turbines, and LPT blade-tip clearances.

Since May, all new Trent 900s have been built to the EP3 standard, which offers improved specific fuel consumption over that available with EP2 variants that were certificated in 2014 (and which followed the original T900 EP introduced in 2012).

The first T900 EP3s have been fitted to the 91st Emirates A380, which was rolled out and began engine runs in early June, ahead of initial flight-testing. The aircraft is scheduled to enter service at the end of this year.

Johnston said that “most” of the Trent 900 engine fleet is now at the EP standard, having been upgraded when passing through regular scheduled maintenance. As much more operating and engineering experience has been accrued, and engine modifications have been introduced, so Trent 900 reliability is said to have improved.

T900 EP2 improvements included optimized fan-blade tip clearance, improved turbine-case cooling (which is better for LPT sealing), optimized IP compressor and improved air-flow system.

A composite R-R measure of disruptions per million engine flight-hours shows a steadily improving trend, suggesting that disruptions in the past three years have generally been around a quarter of those pertaining in 2010, three years after service entry.

Having always had more Airbus A380 customers for the Trent 900 than the competing GP7200 powerplant (and currently selected by 11 out of 17 customers), Rolls-Royce claimed it now also provides more than half of the ordered engines for the A380, accounting for around 53 percent of units (including backlog), said Johnston.

Since the type entered service nine years ago, Trent 900s flown by eight airlines have accumulated more than six million flying hours, with a dispatch reliability of 99.8 percent. —I.G.