Boeing is stepping up work on its revamped 747-400IGW (increased gross weight) and IGW Stretch plan, and is pushing Rolls-Royce and the General Electric /Pratt & Whitney Engine Alliance to firm up plans for new 289kN (65,000lb)-thrust engines to make the proposed aircraft more attractive to airlines.

"You'll see us become fairly active with that," says Mike Bair, vice-president of product strategy and marketing. "If we can get 65,000lb thrust out of the engines then we can get to a maximum take-off weight [MTOW] of 940,000lb [427,000kg] and the same range as that of the -400 [with the stretch], as well as have 10% better operating costs," says Bair, who adds that the study "-is becoming fairly intriguing".

"It is starting to become an attractive package, and we will be talking to airlines relatively quickly about it. There is interest," he adds. The -400IGW plan reverts to the original 1993 concept of a basic gross weight increase, and a related "simple stretch". The resulting aircraft would have identical characteristics, systems, cockpit and other features allowing current -400 rated crew to fly it.

"It is a nice easy addition to the fleet," adds Bair, who says that the outline entry-into-service date could be as early as December 2001. The crucial differences between the latest -400IGW plan and the original growth concepts, which later metamorphosed into the much more ambitious -500X/600X rewinged aircraft, are changes in engine technology and market demand. Another factor enticing the engine makers is the prospect of offering the same engine for the recently launched 767-400, and possibly the 767-300X.

The original 747-400IGW was pegged at around 418,000kg MTOW, which reduced the range of the stretched version by about 925km (500nm), compared to the current -400. The extra range of the 427,000kg version would be achieved by adding more fuel tanks. These would be in the tail box (connecting the horizontal stabilisers, which have fuel in them in most -400 configurations), and forward of the wing carry-through structure. This area is now used to house potable water.

Any temptation to meddle with the wing has been put firmly aside. The stretched fuselage, which would be enlarged with fore and aft plugs by about 2.8m to seat an additional 80-100 passengers, would "probably" follow the IGW.

Source: Flight International