Rolls-Royce is to discontinue production of older versions of its RB211-524G/H engine after successful service entry of the first of its new hybrid versions, the RB211-524HT, last month.

The hybrid engine upon which Rolls-Royce will "standardise" has the same core as the Trent 700, the company's powerplant for the Airbus A330. It declines to say when production of the older versions is scheduled to end, but admits it is no longer offering the standard -524G and -524H variants to airlines.

Cathay Pacific Airways, which became the first airline to use the new engine in revenue service on a 747-400 on 23 April, has reported better than expected performance and has elected to retrofit the rest of its 21-strong fleet.

According to Cathay Pacific engineering director Derek Cridland, the first -524HT, which is fitted in the No 1 position, is showing a 2% improvement in specific fuel consumption and up to a 40% reduction in NOx emissions.

In addition, the engine is registering an improved turbine gas temperature margin of around 50°C on take-off from Hong Kong. "The margin is quite significant and our crews have noticed the cooler engine," says Cridland.

The same aircraft will shortly be re-equipped with a second -524HT in the No.4 position. The airline plans to install modified engines on at least six aircraft by October to support the planned start of non-stop services to Chicago.

Hong Kong Aero Engine Services, the R-R/Cathay joint venture, will modify the airline's entire installed fleet of 84 -524H engines and eight spares, with each engine taking around 45 days. "We will do the modification as the engines go for scheduled overhaul, rather than taking them off-wing," says Cridland.

Other airlines to have selected either the retrofit or the new -524HT include South African Airways and Cargolux, while no customer has yet selected to retrofit the -524G, which powers some Boeing 767s.

Although the updated engine has been picked by British Airways for its next batch of new Boeing 747-400s, it is yet to decide whether to retrofit its 747-400s with the Trent core, and is awaiting the outcome of further trials.

Source: Flight International