The first example, christened Santos-Dumont flew on 3 August 1933 and by the end of 1934 had completed two proving flights across the South Atlantic, with Lucien Bossoutrot at the commands and the future French Admiralty Chief of Staff Henri Nomy as flight engineer. In February 1935 with Aéropostale's only other transatlantic mailplane, the Latécoère 300 la Croix du Sud, out of commission for maintenance, the Santos-Dumont entered service. From then until April, she carried all of France's transatlantic mail at the rate of one crossing per week until rejoined by la Croix du Sud and a new Farman F.220 named Le Centaure. As part of this small fleet, the Santos-Dumont continued in this role until June 1937. Altogether, by that time, she had made 38 crossings of the Atlantic.
In the meantime, the French government had ordered a further three 5190s from Blériot, and the company had borrowed heavily in order to build the aircraft. Suddenly, the contract was cancelled without explanation or compensation, forcing the firm into bankruptcy. Louis Blériot himself died of a heart attack soon afterwards, on 1 August 1936.