“We know what we're going to do,” says Johnston. “We are going through a series of trade studies, and rather than looking at the rotor system which is what the EP did, we are looking at the stator system and introducing better sealing around the LP turbine nozzle guide vane. We are now going through the same level of governance as a new engine. We have an audit team which looks at everything and now we've got a program. We will test an engine and prove what we are doing, although there is not a lot of technology risk because of what we are doing on the 1000/XWB.”
While the A330 market is fiercely competitive, the battle over the A380 is arguably even tougher with reliability and fuel burn under constant scrutiny. The Trent 900-powered A380 has been in service five years and, as of the Paris air show, powers 56 aircraft with six operators. Since 2012 all Trent 900s have been delivered to EP Block 1 standard. Along with elliptical leading edges, this includes tighter LP turbine tip clearance and a new hard coating for the HP compressor drum, all of which contribute to a 1% fuel burn improvement. Upgrades to boost reliability include changes to the HP and IP turbine disc and blades, IP nozzle guide vanes, seal segments, turbine case cooling, a LP location bearing package, IP turbine shaft coupling nut and a software upgrade to the electronic engine controller.
Testing of a follow-on EP2 package, aimed at up to a further 0.8% fuel burn improvement, is now underway. “The first EP2 will be delivered around mid-2014,” says Johnston who adds that the initial operator is expected to be Singapore Airlines. The EP2 configuration includes optimization of the fan blade tip clearance, tighter turbine case cooling control, better sealing of the LP turbine, aerodynamic improvements to the IP compressor and lower drag “A-frame” engine section stators between the core and fan duct. The total improvement is expected to be between 0.5-0.8%. “We'll find out when we start to run,” he adds.
Elliptical leading-edge improvements to the HP and IP compressor blades have also been bundled into retrofit upgrades for the Trent 500 and 800. The Trent 500EP+ will improve fuel burn on the A340-500/-600 by around 0.5%, building on a 1% upgrade already in service. The Trent 800EP, which was launched in mid-2012, will offer a 0.7% fuel-burn reduction. “We have customers for both,” says Johnston, who adds the first engines were installed with the new blades in April. The upgrades are introduced as part of a regular shop visit, but operators pay for the package separately. “They save much more in terms of value,” he adds. The Trent 900EP upgrades, by contrast, are provided as part of the company's TotalCare agreement with all A380 operators.