A350 XWB customers are taking a fairly relaxed view to Airbus's official confirmation that the twinjet has missed its empty weight target by over 2t, but are unlikely to be as tolerant of any further weight growth.

Airbus says that the A350-900 will suffer a fuel burn penalty of "about 1%" after confirming that the twinjet's empty weight will be 2.2t greater than the target at service entry. To compensate, maximum take-off weight has been increased by 3t across the family and the airframer is confident that payload/range performance will not be affected.

A350 chief engineer Gordon McConnell says Airbus established that the manufacturer's weight empty is 2.2t greater than target following the completion of the first detailed "structural sizing" and "bottom-up weight estimate" of the A350-900, and he expects "similar deltas" for the -800 and -1000. The service-entry MWE target for the A350-900 was 113.5t, but this has risen to 115.7t, he adds.

"The weight increase will have a small impact on fuel burn of about a 1%," says McConnell. "We've increased the MTOW by 3t across the family to maintain the payload/range capability." The previously quoted MTOWs for the -800, -900 and -1000 were 245t, 265t and 295t, respectively.

Airbus outlined the details of the Rolls-Royce Trent XWB-powered twinjet's weight growth to existing and potential customers at a programme progress review in early June. McConnell says customers were "quite understanding" and that there is "no issue" with performance guarantees.

Tim Clark, president of Emirates Airline, which has 70 A350s on order, says the weight increase is "manageable at the moment".

Launch customer Qatar Airways, which has ordered 80 A350s, is "watching the weight growth closely as the XWB is earmarked to operate on certain ultra-long sectors that were already critical, notwithstanding the guaranteed performance", fleet planning chief Stephen Vella says.

Vella believes that the A350-1000, as a potential replacement for the Boeing 777-300ER, is "particularly sensitive to weight growth" and suggests that the airframe and engine manufacturer will need to revisit this variant's thrust requirement, which is currently set to be 92,000lb (409kN).

McConnell says that weight growth will not affect take-off performance or create the need for more engine power except "at some specific airfields where discussions have been held with R-R about where we'll need a percent or two more" thrust.

Source: Flight International