Timing of programme makes powerplant providers "a bit nervous" as structure of short-range derivative is redefined

The Boeing 7E7 programme has suffered its first major slippage with the selection of an engine being delayed by around six months to mid-2004. This follows Boeing's decision to fundamentally redefine the short- range (SR) derivative with a much lighter structure and other features.

Boeing 7E7 senior vice-president Mike Bair says the engine makers were "getting a bit nervous with the timing in front of us" and that the schedule slide buys the company "a bit of time at the front end of the programme". Although having no foreseen effect on the mid-2008 target entry-into-service date, the move could have a longer-lasting impact on the overall cost and structure of the programme.

The slide gives the engine makers time to tailor bids to meet the difference in operating requirements between the short-range and baseline and stretch versions. Options under consideration include different fan size, with a scaled-fan derivative for the 7E7SR, which will have a maximum take-off weight up to 90,800kg (200,000lb) lower than other models. Bair says options include "one engine more specialised for the SR marketplace, or maybe one for the SR and base and another for the stretch."

The firm-concept milestone also includes finalisation of the major materials composition of the 7E7, which will now consist, in terms of weight, of 50% composites, 20% aluminium, 15% titanium, 10% steel and the balance of other materials. By comparison, the 777 consists of 12% composites, 70% aluminium, 11% steel and 10% titanium. The use of composites "allows us to make large monolithic parts, which allows us to make huge savings", says Bair, who adds that "in theory" the fuselage could be made up of "three or four large sections".

The market for the 7E7 family is estimated at around 2,500 over around 20 years and will be made up of around 1,000 baseline, 1,000 stretch and 500 SR versions.

Source: Flight International