Jens Flottau Frankfurt

Airbus is doing everything to keep the A350 on the latest revised schedule and thereby please its early customers. But that means important changes must be incorporated later in production, incurring huge additional costs—for Airbus and its suppliers.

Airbus plans to introduce the A350 in several batches, each of which will incorporate changes, with the most significant modifications made in the transition from Batch 2 to 3. The changes affect parts and components throughout the aircraft, and suppliers have been given detailed design targets that specify the amount of weight reduction needed, among other things.

Batch 1 will include all the flight-test aircraft and early produc-tion versions, including MSN4, industry officials say. The first round of relatively minor design changes will be incorporated with MSN5. The more fundamental upgrade will happen with MSN17, say two executives with knowledge of the matter. Airbus has not revealed the exact points of transition, but Andreas Fehring, A350 senior vice president, head of fuselage and cabin, confirms that Airbus has decided to incorporate the A350 changes by batches.

The A350's cabin is one major area in which upgrades are going to be made. From MSN17 on, 40% of cabin parts will be changed, industry officials say. Airbus neither confirms nor denies that figure. The redesign includes cabin bracketing—the way the interior is attached to the fuselage—and the air-conditioning system, as well as other interior components.

Other areas that will see significant modification are structural and wing components.

Airbus is under enormous pressure from customers to limit A350 delivery delays as much as possible. It had to announce a slip of up to three months for the first few aircraft into the second half of 2014 because of the late readiness of software for an automatic wing-drilling machine, an issue that Airbus says has now been resolved.

A further update on the schedule for first flight is expected in October, about a month after the wing for MSN1 is to arrive at the Toulouse final assembly line from Bremen, Germany, where it is being outfitted. There has also been a delay in the assembly process of the first wing pairs, given that drilling had to be performed manually. Airbus hopes it can catch up by expediting later steps in the production process.