Boeing has received board approval to firm up the specifications of its proposed 777-200X/300X growth derivatives and offer them to airlines, as the company gears up towards a possible launch of the new models at the Paris air show in June.

Boeing claims that the -200Xwill be the world's longest-range airliner, capable of carrying 298 passengers in three classes over a distance of 15,900km (8,600nm). The -300X is configured to fly 12,200km with 355 passengers in a tri-class layout.

"This is as far as we believe we can take the aircraft," says John Monroe, senior manager at Boeing's programme-management office. "In May we will call the airline working group back and go over the design with them," he adds.

Subject to launch, Boeing hopes to freeze the design of the aircraft in May 1998, with certification of the -200X in August 2000, and service entry the following month. The -300X would enter service slightly later, in January 2001. The two models will be structurally identical, except for the fuselage plugs inserted fore and aft of the wing on the -300X.

Changes to the wing include structural strengthening, a 1.37m increase in span and the extension of the fuel tanks into the outer wings. Boeing has dropped earlier plans to increase fuel capacity by installing tanks in the horizontal stabiliser, and has decided instead to offer palletised auxiliary tanks in the rear cargo hold as an option for the -200X.

"When we looked at fuel in the tail there were a number of issues," says Monroe. It was determined that only around 7,000 litres of fuel could be accommodated in the tail, "which for some longer missions just isn't enough," he adds.

The -200X and -300X are designed to be powered by 454kN (102,000lb)-thrust engines, giving scope for General Electric, Pratt & Whitney and Rolls-Royce to offer derivatives of existing engines without expensive changes in areas such as fan size. He adds that Boeing has been "-driving to have all three engine manufacturers under memoranda of understanding by 3 March".

GEis expected to offer the 454kN GE90-102B, while P&W is understood to be planning to offer its 436kN PW4098. R-Ris proposing the 437kN Trent 8100, which Boeing says gives the aircraft the same performance as that achieved with rival 445kN engines.

Singapore Airlines (SIA), which has 31 remaining 777s on option, is understood to be particularly interested in the 777-200X proposal, enabling it to reach the USwest coast non-stop. Although the airline has selected the Trent 895 to power its 777s, it is understood to have met all three engine manufacturers to discuss their plans for the growth derivatives. Industry sources suggest that the airline may ask suppliers to re-tender for some or all of the outstanding options.

SIA's joint-venture Singapore Aircraft Leasing Enterprise has also ordered six Trent-800-powered 777s and has options on a further ten.

Boeing, meanwhile, continues to solicit support for the new 777 variants from customers elsewhere in Asia. Korean Air, which has outstanding options for eight 777s, is understood to be interested in both variants, while Malaysia Airlines and Emirates are believed to be looking at the -200X.

Source: Flight International