American Airlines has been given until 3 November by Boeing to define its 777 fleet requirements as engine makers General Electric and Rolls-Royce study growth powerplants for the proposed long-range -200X and stretched -300X versions in response to a revised request for proposals from the US carrier.

American declines to offer specific details of its 777 plans, but they are understood to cover the acquisition of seven -200IGWs in the short term and 12 -200X and six -300X, now held as options, in the longer term. The deadline has been imposed as Boeing seeks a firm launch customer to enable it to give a go-ahead decision on both derivatives by the end of this year. The launch is threatened to slip into 1998 because of continuing uncertainty over the size of the market and of the final-thrust requirement for the longer-range aircraft. Further pressure has also come from Airbus Industrie's aggressive marketing of the A340-500/600 derivatives.

Although General Electric declines to comment on the possibility of a growth GE90, the engine maker has "presented details of a study engine in order to assess market demand", according to one airline source. The study engine is (temperature) flat-rated to 454kN (102,000lb) thrust and fitted with an enlarged 3.17m fan. This is 50mm greater in diameter than the present GE90 but would be relocated further forward to retain the same size nacelle and keep development costs to a minimum. Airline sources say that the revised GE90 is "-not a firm proposal, and is more of a survey than anything right now".

Rolls-Royce has, meanwhile, offered American an uprated version of the Trent 800, the 8104 rated at 463kN, slightly higher than that of the GE alternative. Pratt & Whitney has not committed to any further growth developments beyond the 436kNt PW4098 and has not been invited to pitch by American.

Watching the American decision closely is Singapore Airlines (SIA). The airline is evaluating the 777-200X and Airbus Industrie A340-500 to meet a requirement for an ultra-long-haul aircraft to operate non-stop between Singapore and the US West Coast. The airline has already ordered 30 -200/300s and holds options on a further 31 aircraft, but is unlikely to agree to be a standalone launch customer. o

Source: Flight International