Aircraft

By Guy Norris in Los Angeles

Alliant Techsystems (ATK) has been selected by General Electric to produce the fan composite containment case for the GEnx engine adopted by Boeing as the exclusive powerplant for its stretched 747-8.

The five-year contract is worth "tens of millions" of dollars says ATK, which acknowledges the deal with GE is "by far and away our biggest commercial aviation venture". Until now ATK has specialised in providing composite structures for defence and space applications, including wing skins for the Lockheed Martin F-35. ATK regards its GEnx win as an important strategic step into the expanding civil composites market. "We look at commercial aerospace as a growth opportunity," it says.

ATK will develop the casing for the GEnx-2B67 version for the 747-8, while the fan case for the larger GEnx-1B70 destined for the 787 is being developed by GKN Aerospace at its Alabama Aerostructures site. As the two versions have different fan diameters - the 747 engine measures 2.64m (104in) against the 2.82m of the 787 - GE says "we decided it was best to bid it out".

ATK says design and production of the first containment case "will begin immediately" at Clearfield, Utah, although a decision on whether the final production will take place there or at its large-scale composite manufacturing site in Luka, Mississippi is yet to be taken.

The composite fan case was introduced on the 787 version of the GEnx as a way of saving around 160kg (350lb) per engine as well as improving resistance to damage and reducing maintenance costs. The case is made up using a composite fibre braid, which involves laying down three triaxial braids in a weave mixed with biaxial braids. A slightly thicker weave is laid down for the centre section to replace the traditional Kevlar containment case used in conventional engines. The GEnx-2B67 fan case is likely to be produced in a similar way.