When President Xi Jinping travels to Washington later this month, he is likely to hop over the Pacific on a Boeing 747 jumbo jet. He will also hold the fate of the American planemaker’s much-touted China deal in his hands. Beijing agreed to purchase 200 Boeing aircraft during US President Donald Trump’s visit to China in May. But the deal has yet to materialise – and the negotiations could depend on the outcome of Xi’s coming meeting with Trump in the Oval Office, according to industry...