Airbus is again increasing the maximum takeoff weight of its two A330 models.

The manufacturer plans to offer the A330-300 and A330-200 in 242-ton variants, giving the aircraft an additional 500 nm and 350 nm range, respectively, over the current A330 portfolio.

The changes come on top of increases announced at this year’s Farnborough air show. At the time, Airbus revealed plans to go from 235 tons to 240 tons for the A330-300 and from 238 to 240 tons for the smaller and already longer-range A330-200.

The new option will be available from 2015. Airbus says the 240-ton option likely will be superseded by the latest iteration.

To allow for the added fuel capacity in the A330-300, Airbus is activating the center fuel tank for the first time. Using it has been standard already on the A330-200. Airbus says the improvements will enable airlines to fly the A330-300 on longer-range routes, such as Kuala Lumpur to Paris and Frankfurt, which should satisfy Malaysia Airlines, which has been seeking more range on the A330.

Activating the center fuel tank on the A330-300 raises the fuel capacity of the type from the current 97,530 liters to 139,090 liters.

According to Airbus, there are no structural modifications needed beyond those that have been in the works for the 240-ton version, which will remain an option. For the center fuel tank, which has previously been sealed on the A330-300, pumps and an inerting system will be installed that will be identical to the one used on the A330-200. When Airbus launched the 240-ton variant in Farnborough, it did not foresee the use of the center fuel tank.

The modifications include limited changes to the wing structure, a load-alleviation design and movement of the ailerons to compensate for higher loads during turbulence. This enables Airbus to leave the wing essentially unchanged because the higher expected loads are tempered by the new design.

Airbus also has analyzed the wing’s structural margins and has been able to build on work for the A330-200F.

An aerodynamic improvement package will provide 1% less fuel burn, and Airbus expects engine makers to achieve another 1% reduction. The inboard slat has been reshaped and the flap fairings shortened, but Airbus will not use new A320-style winglets, or “sharklets,” because that would have required significant changes to the wing.

Airbus for years has been developing performance and range improvements for the A330. This has caused the A330-300 to evolve from a medium-haul aircraft into one that now is able to fly most of the long sectors between Europe and North America; the current operational limits, however, keep the A330 from serving the longer intercontinental flights from Asia.

The new 242-ton A330-300 will have a 6,100-nm range at full passenger load, compared with 3,900 nm for the initial 212-ton version built from 1994. That first generation aircraft covered 65% of the Boeing 777-200ER markets because of its much-reduced range, but the latest upgrade will increase this to 94% from 2015.

The updated 242-ton variant also will be able to serve 91% of all existing long-haul markets out of London Heathrow Airport.

Airbus has received 613 firm orders for the A330-300, of which 426 have been delivered, while the A330-200 has 577 firm orders and 476 deliveries. The -300 continues to outsell the smaller -200, with 58 orders received for the -300 in 2012, compared with 11 for the -200. Airbus has delivered 32 -200s and 42 -300s so far this year.