Hong Kong Aero Engine Services (HAESL) will ship Cathay Pacific Airway's first hybrid Rolls-Royce RB211-524G/H-T engine to Boeing in early September for flight certification, following agreement to modify the airline's entire fleet of 21 747-400s.

HAESL is now modifying the first -524G and plans to run the engine in its newly built Tseung Kwan O test cell on 1 September. A second Cathay engine will be sent to Seattle later in the month, along with a third -524G/H-T from R-R, for installation on a newly built British Airways 747-400. Boeing hopes to complete certification by November.

Modification of Cathay's remaining inventory of 92 -524G engines, including eight spares, will begin in March 1998 and is expected to take until 2002 to complete. "As engines come off wing for shop overhaul, we'll fit the 04 module. It will be phased in as engines are due for overhaul and that way they will go out fully refurbished," says Cathay deputy engineering director Derek Cridland.

The 04 module consists of the Trent 700's high-pressure turbine, combustor and compressor.

Thrust ratings will remain unchanged, allowing for the mixing of hybrid engines with existing unmodified -524G powerplants on the same airframe. The improvement will come in the form of a projected 2% better specific fuel consumption (SFC), higher turbine gas temperature (TGT) margins and a 365kg weight reduction. R-R has developed the hybrid engine to counter faster-than-expected -524 SFC and TGT degradation, particularly under hot-and-high operating conditions. "The existing engine has not retained performance as much as we would have liked," says Cridland. R-R and Cathay have declined to reveal the cost of the fleet-wide engine upgrade.

South African Airways has announced that it will fit the new -524G/H-T to two new 747-400s on order, while Qantas and Air New Zealand have also been approached to upgrade their existing R-R-powered 747-400 fleets. BA has ordered -524s for some new 747s, but will not make a decision on the hybrid until flight-testing demonstrates the economics.

Source: Flight International