Aircraft propulsion assembly with a heat shield for thermal protection of a rear aerodynamic fairing of a pylon and a cooling method for the heat shield

The assembly (1) has an air intake for sampling cooling air flow in secondary flow of a turbofan engine (6), and an air circulation pipe (60) for circulating air supplied by the intake. The intake is connected to the pipe and formed in an aerodynamic wall formed of side panels (44) and bifurcation walls of the assembly. The aerodynamic wall is engaged by the secondary flow during operation and longitudinally extended with respect to another aerodynamic wall of the assembly. The former aerodynamic wall delimits an inner cavity (41) and a cavity isolated from the secondary flow. An independent claim is also included for a method for cooling thermal protection floor of a rear aerodynamic fairing of suspension pylon i.e. engine mounting structure, of a propulsion assembly.