General Electric and Pratt & Whitney are negotiating a radical widening of their existing GE-PW Engine Alliance to develop a joint powerplant for the Boeing 777.

The move, which follows Boeing's decision to raise the maximum take-off weight (MTOW) of the proposed ultra-long range 777-200X to as much as 333,000kg (735,000lb), has already sparked off speculation that the two US aero-engine giants will eventually pool all their future large-turbofan activities into an alliance.

The negotiations caught UK rival Rolls-Royce and even Boeing off-guard. R-R, while reacting cautiously to the news, is expected to challenge the legal validity of the move, if it is sanctioned by the two US engine makers. The alliance was originally cleared by the US competition authorities only to offer an engine for the now-defunct Boeing 747-X.

P&W president Karl Krapek says that the companies are "spring-loaded" to propose an engine for the high-gross-weight 777 as well as the 747-400IGW (increased gross weight). He believes that the alliance will propose a 510kN (115,000lb)-thrust engine for the 777. The new engine is expected to emerge from a combination of existing technologies within the two companies as proposed for the original alliance project for the 747-X.

Although more circumspect, GE Aircraft Engines president Gene Murphy adds that there have been "some preliminary discussions with P&W" over the possibility of looking at an engine rated above the 470-490kN thrust range. "We have not fixed on what the thrust range would be, but it would be developed as part of the alliance effort," he says.

Murphy adds that independent talks with Boeing are still continuing on variants of the GE90, but adds that the expense of higher-thrust versions makes such a development more unlikely.

R-R chief executive John Rose says that the company will "-wait and see" what Boeing's final decisions are on the MTOW of the 777 variants before it makes another move. Company sources say, however, that the higher MTOWs will require the Trent 800 to be grown to between 470kN and 480kN, depending on take-off conditions. "That's a huge amount more than where it is today," they concede.

The UK company is "-trying to work out what the market is", as a result of the GE-PW move and adds that the decision to invest in a much higher thrust Trent is "a difficult one" because of the small size of the market. "We've got a lot of work to do to cope with [the new MTOW]," adds the source.

To grow the engine, R-R needs to increase the size of the Trent 800 fan by about 10%, to a diameter of 3-3.15m (120-125in). The core flow would also be increased and other significant changes.

Although Krapek says that rumours of a merger between GE and P&W are "not accurate" he admits that, "-as far as new centreline engines are concerned, then an alliance is the only way they are affordable". He adds, however, that "-no broader collaboration is planned at this time, or is even being talked about". Murphy says that the talks are at a "very preliminary stage".

The chain of events was set in motion on 10 June, when Boeing established a revised baseline configuration for the 777-200X/300X family which set the maximum take-off weight of the -200X at 327,000kg to 333,000kg and the -300X at 318,000kg to 325,000kg. The weights of both were raised in response to requests from prospective customers American Airlines and Singapore Airlines.

Source: Flight International