Airbus seems to have one ambitious goal for its A350 program: two-prong growth. First, by expanding production capacity to better cope with the strong demand. And second, by expanding the aircraft itself to a 400-seat version.

With 756 firm orders in hand nearly a year ahead of the aircraft's likely entry into service, Airbus knows the marketplace is interested. And following a several-year weak phase caused by the redesign of the A350-1000, sales for the stretched version are also picking up, underlining what can be described as a more general trend toward larger twins.

On one hand, there is shrinking demand for the smallest version of the family, the A350-800, as indicated by Aeroflot's partial move away from the jet (see p. 40). On the other hand, the production split between the -900 and the -1000 could turn out far differently than originally anticipated, with the larger variant selling stronger than planned. “There is a good piece of the cake to grab,” Didier Evrard, A350 program chief, says. He points out that the market for A350-1000s has grown by 29% since the launch of the A350 program more than 20 years ago. Nearly 2,100 units are in operation.

Indeed, the capacity of the final assembly line in Toulouse is being expanded to handle a 50/50 split between the two versions. Also, Airbus appears to be coming to the realization that the 350-seater (in standard three-class configuration) may not be big enough in the long term if airlines, as expected, decide to opt for the stretched Boeing 777-9X, which will have around 400 seats.

As part of the assembly line expansion, Airbus is adding a third Station 50, where the current Station 59 has been. That station, which is used for sections preparation ahead of the actual final assembly process, will move to the other side of the line. Currently, two of the four Station 40s are used for wing assembly and two for testing. But when the second part of the final assembly line is completed and line production is launched, all four stations will handle wing assembly while further integration and outfitting work take place in the four Station 30 bays. These are anticipated to be ready for use in late 2014. A fifth Station 30 is scheduled to be in place by late 2015.

Evrard says that the setup will be sufficient for the planned rate of 10 aircraft per month, or more, if market demand is strong. He does not say how many more. At a rate of 10 per month, the A350 would be among the highest-output widebody programs Airbus has ever had, matching the A330 rate. Airbus will build one aircraft per month by year-end—around 10 months ahead of first delivery, and will be building three per month by the end of 2014.

The -1000 is now “entering the industrial phase of the program” as Airbus has begun disseminating data to the tooling manufacturers. Final assembly is to start by the end of 2015, followed by first flight in the second half of 2016 and entry into service by mid-2017. Evrard notes that the challenge will involve phasing it into a production line that is already running at high speed building the -900.

But the advent of the -1000 does not necessarily mean the end of the line for the A350. Airbus is weighing the potential of further stretching the smaller aircraft. Current studies center around how much additional engineering would have to be put into the aircraft's structure and systems to allow for an additional extension to the fuselage.

Airbus's chief operating officer for customers, John Leahy, confirmed for the first time at the International Society of Transport Aircraft Trading (Istat) conference in Barcelona earlier this month that Airbus is studying the idea, however, he later downplayed his comments. Evrard says: “We are not in a hurry to define another product, but if the market needs it, we will do it.”

The current studies are primarily technical. Making the A350 longer would mean a double stretch of the baseline A350-900. Evrard explains that the landing gear for the -1000 is already different and strengthened compared to the -900, and has an upward weight potential in the tens of tons, so that system would not be a limiting factor. He indicates that no serious technical showstoppers have emerged. He points out that: “Others did it, we can certainly do it, too.” This is a reference to Boeing's launch of the 787-10, a double stretch of the 787-8.

The amount of engineering work required hinges on the extent of the stretch and the kind of missions it would have to fly. A stretched aircraft without significant upgrades is likely to lose range. But to be competitive with the 777-9X in terms of range, substantial investment would likely be needed.

Airbus's stance is that the -1000 will be superior even to the -9X. It argues that the Boeing aircraft will be 35 tons heavier (operating empty weight) and will use 15% more fuel than the -1000 while only providing 10% more capacity. And even the smaller -900 reaches the same unit-cost level per seat that Boeing targets for the -9X, says Sophie Pendaries, who heads product marketing for Airbus. Boeing's figures, of course, are much different.

The 777-9X is expected to be formally launched at the Dubai Airshow in November, backed by orders from Emirates, and possibly, Etihad Airways. Lufthansa signed a preliminary agreement for the aircraft last month.

Following the technical studies, Airbus plans to take a close look at the market potential of a larger A350, which would likely take the aircraft into a similar size category as the 400-seat -9X. The A350-1000 is defined as a 350-seat aircraft in three classes—nearly identical in size to the 777-300ER. But the A350-1000 can seat nine additional passengers because it will have only four exit doors on each side rather than five for the -300ER, Airbus says.

Any decision on a formal launch for a further A350 stretch is a long way off and service entry is unlikely before the end of this decade. Following the -900, Airbus plans to deliver the first -1000 around mid-2017, and the future of the -800 is still up in the air. While Evrard says the shrink would not be difficult to do, it could still be a distraction for engineering resources if Airbus opts to build a larger version at the same time.

But for now, Airbus needs to complete flight-testing and certification regimes for the A350-900. Early September 2014 is projected to be the type certification date. That would be followed by first delivery to Qatar Airways soon after. Evrard notes these targets are based on the assumption that the flight-test program and production ramp-up run according to schedule.

Airbus has not specified a date when the aircraft is to be delivered to its first operator beyond stating the second half of 2014. But the target for certification is more defined, indicating the company is comfortable with the results of its flight-test program. “It was important to fly rather early to have some flexibility in the program,” Evrard says. The -900 took off for its first flight on June 14, days ahead of this year's Paris air show.

MSN001 had accumulated 77 flights and 378 flight hours as of Oct. 21 and MSN003, the second flight-test aircraft, had completed three flights and 25 flight hours. Following the completion of minimum unstick speed tests (VMU, the slowest speed at which the aircraft will still take off), Airbus is preparing for flutter testing with MSN001 and icing trials with natural ice before year-end, weather permitting.

Airbus is also progressing with final assembly of MSN002, the third flight-test aircraft and the first that will have a passenger cabin installed. It has begun integrating some cabin elements such as galleys and flight crew rest compartments. MSN002 is planned to be ready for painting before year-end, and final preparations before first flight in February 2014. It is crucial for Airbus to maintain that schedule in order to conduct the six months of testing needed for cabin certification. A February first flight would therefore take certification into the August timeframe. Early long flights simulating long-haul airline operations are scheduled for next spring.

MSN004, which is planned to fly at roughly the same time as MSN002 in February, will have a much shorter lead time because it does not bear a complex cabin or the extensive flight-test instrumentation of MSN001 and MSN003.

MSN005 is to enter final assembly in October and will likely fly in May. It is the second aircraft with a cabin installed and is the first certification-standard aircraft. MSN006 (the first aircraft for Qatar Airways), will follow in November and fly in August 2014.