BRUSSELS (Reuters) – The boss of Europe’s Ryanair Holdings warned on Wednesday the impact of the prolonged grounding of Boeing Co’s 737 MAX on the airline’s growth plans may start to spill over to next summer if the airplane is not flying again by November. Europe’s largest budget carrier needs up to eight months to take delivery of some 50 newly built planes left at the factory by the grounding crisis, so it may have to trim its capacity growth plans for summer 2020 if 737 MAX flights have not resumed by November, Chief Executive Michael O’Leary told Reuters. “Boeing are telling us at the moment they expect to be back flying by the end of September,” O’Leary said in an interview on the sidelines of a meeting of the European airlines lobby A4E, which he also chairs. “I think it will fly before the end of this year. I am not sure they will meet the end of September date, but I take comfort from the fact that it seems that now the American, European, Brazilian and Canadian regulators are working together,” he added. In May, O’Leary predicted a return to service by July but the U.S. Federal Aviation Administr...