By Bjorn Fehrm
March 30, 2016, ©. Leeham Co: Airbus has changed the A350-900 website data to now show the 280t Max Take-Off Weight (MTOW) as the standard MTOW. This weight variant was only reserved for the A350-900ULR before, but is not available for customers buying a standard A350-900 as of 2020.
Three years after the rollout in May 2013 (photo), after ground and flight tests, the company can raise the MTOW of the aircraft to regain range that was gradually lost during the development of the aircraft, even adding range on top of what was originally promised.
The Airbus A350 was designed to fly 315 passengers in a three class layout 8,100nm. During development, the project experienced weight creep, albeit at a moderate 3.3t (t for the metric tonne) on an MEW level (which is the weight of the aircraft without cabin). About a year ahead of certification, Airbus presentations started to show normal range below 8,000nm.
The original range figure was for the original 268t MTOW which was the initial weight variant for the aircraft. At certification of the A350-900 in 2014, three additional weight variants were defined; 260t, 272t and 275t. At the time, Airbus then showed the aircraft as flying 7,750nm with 315 passengers, now in a two class layout.
As of May 2015, the three class layout was reintroduced but now with lie-flat reverse herringbone business class seats at 42-inch pitch, a premium economy cabin at 38-inch pitch paired with an economy cabin at 31-inch pitch. Together with the new aft galley layout from the A350-1000 (with lavatories at the side), this gave a 325 seat capacity and a 7,600nm range. The weight variant was not clear for this range figure.
During spring and summer 2015, Airbus was competing to fill Singapore Airlines’ need for non-stop flights to the US. Testing of the A350-900 had shown that there were additional margins in the design, aerodynamically and for MTOW, on top of the 275t that was included in the certification. A 280t variant in a special configuration to lower the passenger payload to around 170 passengers could fulfill the most daunting mission that Singapore Airlines wanted to fly, Singapore-New York direct.
To reliably fly this mission, which could stretch to up to 19 hours worst case, the aircraft had to be equipped with adjusted fuel cut-off probes in the tanks, to reach a total fuel load of 165,000 litres (standard is 141,000l). With these changes, the variant was called A350-900ULR. Incorporated in the variant were aerodynamic and engine improvements totaling 2%.
280t for all
Since the Singapore Airlines order, several customers have demanded that the extra capability of the A350-900ULR should be available, but in a flexible form. Not all needed the extra fuel capacity; they fly missions with normal loads for which the standard 141,000l is enough. At the same time, they needed a higher MTOW. Philippine Airlines needed 278t to fly their missions.
To respond to customer demands Airbus decided that as of 2020, when the aerodynamic improvements of 1% (mainly changes to fairings) and a Rolls-Royce engine PIP (Product Improvement Package) of 1% will be available, the weight variants that can be ordered will include the 280t variant.
Additionally, the special fuel configuration of the A350-900ULR will be available, as will a 260t regional variant. In all cases the different weight variants are paper changes to an identical airframe making later in-service weight variant changes possible.
So why would an airline change to a different weight variant later in the aircraft’s life? Aircraft price and underway navigation and landing fees are based on the aircraft’s MTOW. To buy just the weight variant necessary to do the job is a way to save operational costs for the airlines. If operational conditions later change, it is a bonus to be able to adapt the aircraft.