A method and system for predictive maintenance of electronic equipment on board an aircraft (1). To produce a prognosis, the following are provided: a step (48) of modeling the equipment (3) with a model (53) for damage by an external aggression; a step (49) of simulating the damage up to failure; a learning step (64); a step (65) of classifying calculated and normalized values; and a fusion step (61) giving the real prognosis of the time to maintenance in units of time. The invention applies in particular to a rotary wing aircraft (1), e.g. a helicopter drone.