Proposals revealed by flightglobal.com earlier this year to reprofile and revise the XWB’s nose section have been confirmed by the airframer. The design now incorporates a configuration derived from the A380 with a forward-mounted nosegear bay and new cockpit-window glazing.
The unusual four-window arrangement that was a feature of the original XWB design has gone, with a more conventional six-panel flightdeck windscreen similar to its big sister in its place.
The cockpit fuselage section will be constructed from aluminium lithium, with Airbus deciding against adopting a one-piece carbonfibre structure that it had been evaluating preiously.
A350 XWB chief engineer Gordon McConnell says that the nose reprofile was made partly for improved aerodynamics and also to enable the overhead crew rest to be installed further forward and eliminate any encroachment in the passenger cabin.
He adds that strength requirements for birdstrike protection were partly behind the decision to adopt a metallic nose structure. "If we went for a composite structure we'd have to reinforce the area above the cockpit with titanium which is expensive," he says.
A key change is the switch from metallic to carbonfibre fuselage frames, although the fuselage crossbeams remain metallic. "These could also be switched to carbonfibre, but we're still running trade-off studies," says McConnell.
The plan to use large carbonfibre fuselage panels for the main fuselage skin has not changed.
The decision to switch to carbonfibre frames comes after several of Airbus’s key customers, including International Lease Finance and Emirates, had been vocal in their criticism of the XWB’s fuselage construction in recent months.
"The change addresses concerns over possible corrosion risks between metallic frames and carbonfibre," says McConnell. He adds that the switch also eliminates some of the "perceived maintentnace programme inspection requirements" that resulted from the use of metallic frames.
Airbus remains on target to reach its "freeze of aircraft concept" in October 2008. The first version of the three-model XWB family to enter service will be the 314-seat -900, in mid-2013.