Rolls-Royce is planning improvements to the Trent 1000 engine for the Boeing 787, amid reports that it is not meeting the specific fuel consumption target. Delays to the 787 have given both R-R and rival supplier General Electric more time to mature their engines before entry into service.

R-R will not comment on claims that the Trent 1000 is behind both its sfc target and the fuel burn achieved by GE's GEnx engine, but says: "Performance targets are worked throughout all development programmes. We laid out a continuous improvement programme before the 787 roll-out, and our aim is to attain the best fuel burn on the aircraft."

The Trent 1000 was certificated in August 2007. "We have identified a number of areas where we believe improvements are possible, and we will drive these into the product," says R-R. "In the additional time now available before entry into service, we will consider how we can complete these actions."

As launch engine on the 787, the Trent 1000 was scheduled to enter service in May 2008, but Boeing has pushed back first deliveries to late November or December. First flight of the 787 has been delayed from late August 2007 to late March. First flight of the GEnx-powered 787, originally set for October 2007, is now expected by mid-2008.

GE says the GEnx's fuel consumption is on target and that airlines are telling it the engine's sfc is 2-3% better than the Trent 1000's. Engine certification is expected early in 2008.

The company says it is using the extra time before service entry to introduce durability improvements into the GEnx, making slight changes to components and to cooling-air schemes in the turbine section based on test results.