With production of the Boeing 787 properly under way, after the airframer delivered the first example to Japan's All Nippon Airways in September, the pressure of attention will switch to Toulouse where Airbus is trying to keep to its deadline of beginning final A350-900 assembly by the end of this year.

Airbus and its parent have frequently described the timetable for the A350's development as "challenging", a more investor-friendly term than "problematic", although few are in doubt that this is precisely what the airframer means.

Chief executive Tom Enders gave the clearest indication yet that the A350 could miss its end-of-year target date for starting final assembly, after insisting that the aircraft would not be rushed into unmanageable production.

Airbus is desperate to avoid a repeat of the A380 debacle during which large unfinished sections of the jet had to be reworked on the final assembly line having been shipped before they were ready. This painful memory, and the situation with the 787 delays, have left the European airframer keen to demonstrate a degree of humility.

During the opening ceremony of the A350 wing plant at Airbus's UK facility in Broughton, Enders stressed that the A350 involved a "big jump" in technology and "a lot of unknowns".

"There's no magical date by the end of the year," he said. "It's nice to keep to a schedule. But it's more important that we have a manageable level of outstanding work. We shouldn't reach the stage where [assembly] isn't manageable."

Executive vice-president for programmes Tom Williams said the airframer was still expecting "sections on the final assembly line by the end of this year". But he said the aircraft involved "a lot of innovation" and added: "Clearly that's been difficult." He admitted that achieving a "flyable aircraft" by the end of 2012 was "tight", and added: "We're down to short straws."

Broughton has taken delivery of wing components for the first flying example, MSN1, but initial final assembly will focus on fuselage sections for the A350 static test aircraft.

Enders highlighted the problems experienced by the 787, which paid the price for taking an ambitious leap into composite manufacturing.

France's St Nazaire plant, where the fuselage is being shaped, has gradually been taking delivery of the various sections of the A350-900, including the sub-assemblies comprising the 40%-composite nose of the twinjet - the cockpit window section, forward fuselage and passenger doorway, plus the nose-gear bay from the Aerolia plant at Meaulte.

This nose section is set to be completed and mated with the 13m forward fuselage, nearing completion at the Premium Aerotec facility based at Nordenham. The structure, which is built from large panels fitted to a floor grid in line with Airbus's design for simplifying the manufacture, will be transported to Hamburg for systems installation within a few weeks.

Several other large components of the A350 have already undergone transport. The centre wing box as well as the keel beam, which has been integrated with the aft lower fuselage, has moved from assembly at Nantes to St Nazaire.

Both the upper and lower wing covers - the former built in Stade, Germany, the latter at Illescas, Spain - have been moved to the UK's Broughton facility where the primary wing structure is manufactured. A350 wings will be shipped to the final assembly line at Toulouse via Bremen where, in early 2012, the flaps, slats and other systems will be installed.

Airbus opted for composite panels to build much of the A350 fuselage, a strategy aimed at simplifying the manufacture, although it is taking barrel assemblies for the rear fuselage from Illescas.

Initial fuselage panels have been produced by the Premium Aerotec and Spirit AeroSystems. Both the main and nose landing-gear assemblies were delivered to the UK's Filton plant for testing in the first half of the year. Airbus has also expanded its Chinese production plant at Harbin to prepare for future rudder and elevator work.

While specifically confirming any change in the schedule, Enders told a French newspaper that if the A350 team needed "a few more months" to prepare for final assembly then it would be "better to delay".

Keeping the A350 from straying has already involved Airbus's being prepared to rescue a supplier - German tubing firm PFW Aerospace - from a financial crisis. The firm, which was also selected as a Boeing 787 supplier, is manufacturing bleed air tubes for the Airbus jet.

By the end of September more A350s had been cancelled in 2011 than ordered, and while Airbus chief operating officer for customers John Leahy says there are few slots until 2017-2018, the plateau is partly the result of dwindling interest in the smallest variant, the A350-800, but also the uncertainty over its largest, the A350-1000, which underwent a substantial design change earlier this year aimed at improving its ability to compete with the Boeing 777-300ER.

Rolls-Royce, whose baseline 84,000lb Trent XWB engine for the A350-900 has just completed endurance tests in Madrid during which it exceeded original targets, is to commit to a higher-thrust version of the powerplant for the -1000 as part of the change.

Airbus's efforts to overhaul the -1000 have been greeted with a lukewarm response from Qatar Airways and Emirates, both among the initial customers, but Enders is adamant that the airframer will not reshape the aircraft further. "For us, that is the solution," he insisted.

With customers questioning whether Airbus's big twin can truly match the 777-300ER, Boeing has joined the battle by turning its attention to revamping the 777, under a study for twinjets designated the 777-8X and -9X.

Among the major upgrades for such an aircraft would be replacement of the metal wing with a composite structure, as Boeing aimed to capitalise on 787 technology and the delayed entry into service, to 2017, of the A350-1000. The aircraft could also feature a smaller General Electric powerplant, and will aim to reduce per-seat fuel burn by 15%.

Boeing, which is progressing with the 787-9, is simultaneously examining the timing of the proposed 787-10, and -10X, as part of its strategy to counter the A350 family.

Source: Flight International