Boeing 787

The General Electric GEnx (General Electric Next-generation) is an advanced turbofan under development by GE Aircraft Engines for the Boeing 787 and Airbus A350. The GEnx is intended to replace the CF6-80 in GE's product line.

The GEnx and the Rolls-Royce Trent 1000 were selected by Boeing following a run-off between the three big engine manufacturers. Pratt & Whitney's proposal was unsuccessful, possibly due to having been an all-new, and thus, untested design. The GEnx uses some technology from the GE90 turbofan, including the composite front fan blades and a compressor stage.

For the first time in commercial aviation, both engine types will have a standard interface with the aircraft, allowing any 787 to be fitted with either a GE or RR engine at any point in time. Engine interchangeability makes the 787 a far more flexible or liquid asset, allowing airlines to change from one manufacturer's engine to the other's in light of any future engine developments or when acquiring 787 from other operators/lessors. The engine market for the 787 is estimated at US$40 billion over the next 25 years.

Another first is the elimination of bleed air systems, which use high temperature/high pressure air from the engine to power aircraft systems, e.g. air-conditioning and anti-ice systems. The GEnx and the Trent 1000 allow a move towards the "electric" airplane.

The GEnx is expected to produce thrust of 55,000 to 70,000 lb_f (245 to 311 kN) with first tests commencing in 2006 and service entry by 2008. While Boeing predicts reduced fuel consumption of up to 20% the 787's engines are also expected to be significantly quieter than current turbofans.

Both General Electric and Rolls-Royce have confirmed that they are in talks with Airbus with regard to supplying bleed-air (and thus less efficient) versions of their new generation engines for the Airbus competitor to the 787, the A350. The GEnx will be offered first, with the Trent 1000 being available at a later date.

General Electric has a 64% risk-sharing stake in the GEnx program. Other stakeholders include Ishikawajima-Harima Heavy Industries (IHI) at 15% and Carlyle Avio at 12%. Volvo Aero, Techspace Aero , and Mitsubishi Heavy Industries hold the remaining share. Notably absent is General Electric's frequent partner, SNECMA, who has historically been GE's largest partner on aircraft engine projects. SNECMA may still supply parts, however, but is deeply involved with the PowerJet joint venture.

Technology

As a totally brand new engine, among the technology used for weight savings are;

• 111-inch composite fan blades with titanium leading edge
• Fan case made of composites material

Fuel burn reduction technologies include;

• Fan bypass ratio of 9.5:1 which also reduces noise
• High pressure compressor based on GE90-94B with 23:1 pressure ratio
• Counter-rotating spools (first employed by Rolls-Royce Trent 8104)
• Combustors with improved internal airflows which also reduces enviromentally-harmful emissions

And features to reduce maintenance and increase engine life such as;

• Spools with lower parts count
• Cooler internal engine temperatures using more efficient cooling techniques

All these should yield a fuel burn of at least 15% better than GE's CF6-80C2 engines for widebody aircraft. It is available in both normal bleed configurations and bleedless configurations (as in Boeing 787).

Engine selections

In the most significant 787 order, that of Japan's All Nippon Airways, Rolls-Royce was selected as the engine supplier on October 13 2004. ANA's 50 firm aircraft order and the earlier selection of RR by Air New Zealand has left the British company as the lead engine supplier for the 787. The Japanese deal was considered vital by both companies, due to the size of the order (valued at US$1 billion (£560 million)) and the trend setting decisions of the carrier. GE previously held an almost monopoly position in the Japanese market.