Airbus is preparing to brief airlines on its plans to develop heavier, longer-range growth derivatives of the A340-500 and -600, as it enters the final phase of commercial negotiations with Pratt & Whitney and Rolls-Royce to decide whose engine will be offered on the baseline aircraft.

The growth versions of the-500 and -600 would be fitted with around 10% more-powerful engines, offer higher operating weights, and would provide additional fuel capacity for about 925km (500nm) of extra range, compared with the baseline -500 and -600 specifications.

"We have room to grow - the thrust is there to allow us to do it," says Alan Pardoe, A330/A340 product manager. Pardoe says that the two rival engines on offer, the P&W PW4557 and R-R Trent 500, "-meet our technical requirements. The Trent is a more radical approach, resulting in a better specific fuel consumption.

"Pratt has taken a lower-risk approach, which gives less improvement in fuel consumption, but which gives a lighter propulsion system." The result is that, "-with both engines, we achieve very similar fuel-consumption results", Pardoe says.

The commercial discussions with both suppliers are expected to be concluded shortly, followed by the signing of a memorandum of understanding in time for the Paris air show in June. Both engine makers have indicated that they require a "sole-source" agreement to justify development costs.

The baseline -500 is configured to carry 313 passengers in three classes over 15,360km, and will be powered by 236kN (53,000lb) -thrust engines. The longer -600 has 378 seats, but 1,850km less range, and initially requires engines rated at 249kN.

Pardoe says that 276kN engines will be available for later versions, while the new, enlarged, A340 wing has plenty of internal volume for increased fuel capacity.

The new three-post, 12-wheel, main undercarriage is also designed to accommodate higher weights than the initial 356t maximum take-off weight (MTOW) of the baseline -500/600.

Leading potential launch customers include Cathay Pacific and Singapore Airlines, for the-500, and Swissair for the -600. The aircraft, aimed at the 747 "Classic" replacement market, will compete with Boeing's proposed 777-200X and -300X. A340-500/600 service entry is planned for late 2001.

Airbus is preparing to offer 91t and 93t MTOW versions of the A321, to match the US transcontinental range of the A319/A320. The 91t development would have a range of 5,365km, while the 93t version would provide more than 5,550km. Extra fuel capacity would be added through the one or two auxiliary fuel tanks in the rear cargo hold. The current high-gross-weight A321-200 has an MTOW of 89t and a range of 5,000km.o

Source: Flight International