China Southern Airlines (ZNH.NYSE, 600079.SH, 1055.HKG), Asia’s largest carrier by passenger numbers, said it may scrap a purchasing contract with Boeing (BA.NYSE) after its first order for 10 of the US plane manufacturer’s 787 Dreamliners was delayed until July 2012, Bloomberg reported. China Southern CFO Xu Jiebo said the delivery of the planes has been delayed from around year-end because of certification issues, and that the company wouldn’t “rule out the possibility of canceling or adjusting the 787 orders.” China Eastern (CEA.NYSE, 600115.SH, 0670.HKG), the country’s second biggest carrier, has already swapped its order for 24 Dreamliners for smaller Boeing planes, citing late delivery and slowing demand for international travel. Spokespeople for Air China (601111.SH, 0753.HKG) and Hainan Airlines (600221.SH) said that there have been no changes in their orders for 15 and 10 Dreamliners, respectively. Boeing received certification for the 787 from American, European and Japanese regulators in August, and has already won orders for more than 800 Dreamliners, making it the company’s fastest selling jet ever.