Engine makers' views
As lead engine supplier on the A380, Rolls-Royce's 70,000lb thrust (312kN) Trent 900 powered the aircraft on its maiden sortie on 27 April 2005 and the bulk of the test fleet during the flight trials and certification programme.
The Trent has been selected for nine of the 16 customers so far and is used by two of the three airlines operating the type - Singapore Airlines and Qantas - which account for 14 of the 20 aircraft delivered.
R-R's rival on the A380 - General Electric and Pratt & Whitney's Engine Alliance joint venture - could be described as a "one-trick pony" because the double-decker is the only application for its single product, the 70,000lb-thrust GP7200.
The US company has just six customers (including Air Austral's two-aircraft commitment), but has been selected to power more A380s than R-R in unit terms (94 firm/two commitments versus 90 firm) and has laid claim to the biggest prize on the programme so far - Emirates with its 58 aircraft on order.
Richard Keen, who is R-R's head of marketing for Airbus programmes, says that although "a lot of useful lessons were learnt" from the extensive flight-test programme during which the Trent-powered A380 test fleet accumulated 22,000 flying hours, "you will always see new issues once the aircraft goes into service".
Launch operator SIA has made precautionary Trent 900 engine changes that Keen attributes to the careful approach the airline took to the A380's introduction. "SIA wanted to do everything to protect its operation in an absolute way, which we fully supported. If it saw anything that might be a future operational risk, it took a precautionary approach that necessitated an extra engine change or two."
Trent 900 marketing manager Elise Hresko says that the precautionary engine changes were generally in response to post-flight advisory messages on the maintenance report. "They were genuine alerts - rather than nuisance warnings - but the engine was still within limits," she says. "At the beginning of the operation, the limits had been drawn in a very conservative manner to help us understand the engine's behaviour."
Keen says that all the "teething problems" suffered by SIA have been "closed out or contained" under R-R's "project zero" programme, which "is a zero-tolerance approach to operational disruption". He adds that the Trent 900 operated for seven months at 100% reliability and the "disruption index" now stands at 99.8%, which is line with a mature Trent product.
R-R has identified that the first two of SIA's three in-flight shutdowns were "non-basic", says Keen, which means the engine's basic design was not at fault and nothing has had to be changed. "We're waiting to see what caused the third shutdown as the engine is undergoing strip-down and inspection."
Engine Alliance says the five GP7200-powered A380s flying with Emirates have a 99.9% "departure reliability rate", have suffered no engine-related in-flight shutdowns or aborted take-offs and have an unscheduled engine removal rate (per 1,0000 engine flying hours) of 0.051 (all figures are 12-month rolling averages to October 2009).
© Max Kingsley-Jones/Flightglobal
Emirates has been delighted with the GP7200 so far
Emirates president Tim Clark says the engines powering his A380s have performed well and had no major issues.
Engine Alliance president Jim Moravecek says that the GP7200's fuel burn came in 0.9% ahead of Airbus's specification, which gives it a 1% advantage over its rival.
R-R's Keen disputes this claim, but the engine maker is working on a two-pronged development programme for the A380's Trent, the first of which, the 900EP, has been launched and is available from 2012.
This upgrade, which is not retrofittable, involves the incorporation of elliptical blades and vanes to the high-pressure and intermediate pressure compressors, and will deliver a 1% improvement in fuel burn.
Further improvements, borrowing technology from the Trent 1000 and XWB, are in the pipeline, Keen adds.