A gas turbine engine for an aircraft, the engine including: an engine core comprising a turbine, a compressor, and a core shaft connecting the turbine to the compressor; core casings surrounding the engine core; an aerodynamic cowl which surrounds the core casings; a propulsive fan located upstream of the engine core, the fan generating a core airflow which enters the core engine and a bypass airflow which enters a bypass duct surrounding the aerodynamic cowl; a circumferential row of outer guide vanes located in the bypass duct rearwards of the propulsive fan, the outer guide vanes extending radially outwardly from an inner ring which defines a radially inner surface of the bypass duct; the aerodynamic cowl being rearwards of the inner ring and including two door sections located on respective and opposite sides of the engine, each door section being pivotably openable about an upper edge thereof to enable maintenance access to the engine core; one or more engine accessories mounted in a space between the core casings and the aerodynamic cowl; one or more ventilation inlets which receive a portion of the bypass airflow as a cooling flow for the engine accessories; the ventilation inlets being configured to convert at least a portion of the kinetic energy of the bypass flow received therein into a pressure rise such that the pressure of the cooling flow is increased relative to the pressure of the bypass airflow; and a manifold in fluid communication with the ventilation inlets to collect the cooling flow therefrom, the manifold having plural exhaust holes therefrom through which the cooling flow leaves the manifold to impinge upon and thereby cool the engine accessories; the engine characterised in that the aerodynamic cowl further includes a keel beam which extends rearwardly from the inner ring at bottom dead centre thereof to provide latching formations for latching to a lower edge of each door section when it is closed, and the ventilation inlets are located on the radially outer surface of the keel beam. an engine core comprising a turbine, a compressor, and a core shaft connecting the turbine to the compressor; core casings surrounding the engine core; an aerodynamic cowl which surrounds the core casings; a propulsive fan located upstream of the engine core, the fan generating a core airflow which enters the core engine and a bypass airflow which enters a bypass duct surrounding the aerodynamic cowl; a circumferential row of outer guide vanes located in the bypass duct rearwards of the propulsive fan, the outer guide vanes extending radially outwardly from an inner ring which defines a radially inner surface of the bypass duct; the aerodynamic cowl being rearwards of the inner ring and including two door sections located on respective and opposite sides of the engine, each door section being pivotably openable about an upper edge thereof to enable maintenance access to the engine core; one or more engine accessories mounted in a space between the core casings and the aerodynamic cowl; one or more ventilation inlets which receive a portion of the bypass airflow as a cooling flow for the engine accessories; the ventilation inlets being configured to convert at least a portion of the kinetic energy of the bypass flow received therein into a pressure rise such that the pressure of the cooling flow is increased relative to the pressure of the bypass airflow; and a manifold in fluid communication with the ventilation inlets to collect the cooling flow therefrom, the manifold having plural exhaust holes therefrom through which the cooling flow leaves the manifold to impinge upon and thereby cool the engine accessories; the engine characterised in that the aerodynamic cowl further includes a keel beam which extends rearwardly from the inner ring at bottom dead centre thereof to provide latching formations for latching to a lower edge of each door section when it is closed, and the ventilation inlets are located on the radially outer surface of the keel beam.