Paris Air Show

Trent 900s for A380 ‘better than spec’

 - December 13, 2006, 12:34 PM

Everything is going very well with the Rolls-Royce Trent 900, which has logged more than 400 engine hours aboard the Airbus A380 since the very large airliner’s April 27 first flight, according to managing director (airline) Charles Cuddington. With almost 20 flights completed by the beginning of June, initial engine performance is said to be “better than spec,” reflecting earlier experience on the A340 flying testbed. Currently Rolls-Royce is preparing to produce customer engines for first operator Singapore Airlines (SIA).

Cuddington acknowledged that these will be built later than expected, following a revised Airbus schedule that will see the first A380 delivery much later in 2006 than the originally planned second quarter of the year. Airbus attributes the delay to internal factors and to customers’ late selection of buyer-furnished equipment.

R-R will discuss the new timetable with Airbus after the airframe company has renegotiated delivery dates with SIA and other early customers such as Air France and Emirates Airline. The latter carriers have chosen the alternative General Electric/Pratt & Whitney Engine Alliance GP7200 powerplant that was derived from designs aimed at the stillborn Boeing 747-500 and -600 projects, which were dropped in 1997.

Cuddington said that the revised delivery schedule should permit the introduction of modifications “that are always coming along.” With Airbus and SIA agreement, this could allow R-R to deliver higher-standard initial engines that incorporate early flight-test derived enhancements.

The flying testbed engine is to be returned to the Derby factory in the UK for strip examination. Recent tests have included natural icing trials as part of the ground-ingestion element of engine certification procedures.

Meanwhile, R-R has shipped 18 flight-test engines to Toulouse in addition to the original testbed unit. The Trent 900 has an advantage over the GP7000 in that, if necessary, it can be “swallowed whole” by a Boeing 747 freighter, whereas the competing powerplant must be broken down by removing–or, rather, not installing–the fan blades and case. Alternatively, GP7200s can be flown in a larger aircraft, such as an Antonov An-124 or an Airbus Beluga special freighter. Routinely, Trent 900s are delivered to Airbus by road. The Engine Alliance regards the breakdown as part of the normal production process.

The initial variant of the engine is the GP7270, which will be followed by the A380F freighter’s GP7277 powerplant, with both to be certificated at 76,500 pounds thrust. “Quite a bit has been done,” said Engine Alliance president Bruce Hughes, on the subsequent GP7282 engine that is being developed for heavier increased-gross-weight A380 variants. This version will generate 81,500 pounds thrust as a result of running at “increased red-line temperatures,” said Hughes.

The Engine Alliance expects to have completed 80 percent of initial development testing by the end of next month, when reports will be completed for the U.S. Federal Aviation Administration ahead of formal airworthiness approval (which had been scheduled for October). By coincidence, that is the date when the alliance is scheduled to start building production engines for delivery in the first three months of 2006 (but certification schedules are now subject to the Airbus revision, and approval could even slip to early 2006, said Hughes).

Two A380s are earmarked for GP7200 certification work: manufacturer’s serial number (MSN) 009 will be used for performance and propulsion system tests, while MSN 007 (the second A380 to sport a passenger-configured cabin) will undertake route-proving flights. MSN 007 will fly initially with Trent 900s before being re-engined with the GP7270 by the middle of next year. Since the two engine designs have different mounting points, this process will involve a simple change of the pylon.

The delay in delivery of initial A380s could close the gap between service entry of the respective engines, especially as the alliance is continuing to work with the original schedule while awaiting word (expected this month) from Airbus on revised dates, said Hughes.

A second and final round of GP7200 flight tests began on June 3, using a production-standard engine (serial number 004) fitted with modified blades in the first three high-pressure compressor stages, accessory changes and a modified nacelle. This series of flights, which runs until early August, involves testing of performance, operability, under-cowl temperatures (including ventilation) and thrust-reverser and nacelle stresses and temperatures.

Initial tests, involving 30 engine hours in eight flights (with engine 004 before its modification), had covered operability, engine stresses, temperatures and pressures, but did not yield so much performance information, according to Hughes. This second series is scheduled to involve 100 hours of testing over 22 flights.