Airbus A350 launch customer Qatar Airways is unconcerned about the three-month slip in the twinjet's first flight schedule, believing that the buffer built into the test programme should ensure its deliveries remain on track.

Airbus confirmed to a gathering of existing and potential customers in Nantes during its recent fifth-programme progress review that final assembly and the maiden flight of the first A350-900 have slipped by three months to the third quarter of 2011 and mid-2012, respectively, due to issues that have cropped up during the design of the airframe's carbonfibre structure.

However Airbus remains committed to the mid-2013 first delivery to Qatar Airways, which has 80 of the Rolls-Royce Trent XWB-powered twinjets on order.

"We are currently relaxed about the slippage," says the airline. "The three-month delay is easily accommodated within the flight-test timescale, which has been reduced from the very long 15 months originally planned, to 12 months, which is the industry norm."

The programme's chief engineer Gordon McConnell says the airframer knew it had "a good buffer" built in to the original 15-month flight-test programme and had been looking at ways to do it quicker.

Programme manager Didier Evrard says that as the detailed definition of the baseline A350-900 progressed last year and Airbus prepared to begin machining the first parts, "I had to give a bit more time to our structure designers for deeper validation".

He says that the reason for Airbus's caution was that the "process for development of structure in composite is really different [to metal] - you cannot start machining the part and then improve the design".

Four areas of the design were affected: the airframe sizing, the wing-root joint, the fuselage's electric structural network (which helps the conductivity of the carbonfibre fuselage) and the fuselage damage tolerance. The first two of these have been resolved and the fix approved, while the others have a solution under validation.

The slip has already ha an impact on production, with the first material cut on the A350's horizontal cruciform sliding from November 2009 until 5 March this year, which has also pushed back the assembly of the centre wing box by three months to mid-2010.

Evrard says that the A350's systems development is "roughly" on schedule but having consumed margin on structures "it is important that we secure and find other buffers in the phases to come".

However, he is optimistic that the schedule can be met: "It's not going to be easy, but we have a good chance to be there or thereabouts."

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Source: Flight International