A method for optimizing operability of an aircraft propulsive unit, and a self-contained power unit implementing the method. The method removes mechanical bleed constraints in engines during transient flight phases of an aircraft to optimize operability of the engine assembly during the phases. To this end, a supply of power is provided, particularly during the phases, by an additional indirectly propulsive engine power source. The method for optimizing operability of the propulsive unit of an aircraft including main engines as main drive sources includes, using a main engine power unit GPP as a power source, providing all the non-propulsive power and, during the transient engine phases, at most partially providing additional power to the body of the main engines.
