Pratt and Whitney and General Electric are wrestling to find versions of their respective PW4000 and CF6 engine families to power the latest proposed growth developments of the Boeing 747-400. Their moves follow the failure of US and European regulatory authorities to relax the ruling that bars use of the Engine Alliance GP7000 on aircraft smaller than 450-seats.
Boeing has asked both US engine manufacturers, along with Rolls-Royce, to study engine options to power a range of proposed increased gross weight variants of the 747-400. The Seattle-based airframe manufacturer is looking at a number of new 747 derivatives sized in between the recently launched 412,770kg (910,000lb) -400XF up to 431,300kg in the wake of its recent decision to shelve the larger 747X (Flight International, 8-14 May).
"They asked us to participate in that study to look at what engine alternatives there are for each of these various gross weights," says Bob Leduc, P&W executive vice president. "We would like to get a lot of work done over the next four to five weeks so that by the end of June we're in a position to decide which way we're going."
At the top end of the weight range the aircraft will need a 65,000lb-(290kN) thrust engine and P&W is looking at a version of the PW4168 currently powering the Airbus A330. The engine's inlet would need to be modified to cater for the 747's higher cruise mach number, while pylon installation and weight must also be studied. For the 412,779kg aircraft the alternative is the smaller PW4062 now on the Boeing 767-300.
GE is looking at the growth CF6-80G2, while Rolls-Royce is studying variants of its proposed Trent 600. A major consideration for all three manufacturers will be the ability of these engines to meet anticipated lower noise limitations at Heathrow.
Technically, a version of P&W and GE's jointly developed GP7000 would lend itself to the 747, but the aircraft's current 414-seat capacity falls outside of the 450-seat minimum threshold set for the Alliance by the US Government and European Union.
Source: Flight International
