DUBAI (Reuters) -Abu Dhabi’s Etihad Airways on Wednesday signed a letter of intent to order seven Airbus A350 freighter aircraft, European planemaker Airbus said at the Singapore Airshow. The value of the potential deal was not disclosed. The state-owned airline had been considering the Airbus freighter and the competing 777X cargo jet developed by Boeing. Etihad Chief Executive Tony Douglas said the Airbus jets would play a key role in the airline’s cargo strategy. He has previously said that the Airbus A350 and Boeing 787 Dreamliner widebody passenger jets would become the backbone of its fl…