SEOUL :AirAsia on Friday signed a memorandum of understanding with Airbus to buy 50 long-range A321XLR planes with conversion rights for another 20 of the single-aisle jets, as the budget airline nears the end of a restructuring process. Reuters reported last month that Tony Fernandes, CEO of AirAsia owner Capital A Group, was in talks to buy 50 to 70 of the latest Airbus narrow-body model, which would include the ability to convert some of the airline's large, existing Airbus order book into