A gas turbine engine, comprising: a turbine section; an OD flow rail; and a stator vane assembly in the turbine section, the stator vane assembly comprising: a stator vane having a first end opposite a second end; an ID stator vane platform coupled to the first end; an OD stator vane platform coupled to the second end, wherein the OD stator vane platform comprises: an OD forward rail extending radially from the stator vane platform; and an OD aft rail extending radially from the stator vane platform and located axially opposite and aft of the OD forward rail, wherein the OD aft rail comprises: an OD axis defining a perpendicular direction relative to the OD aft rail; an OD leading face; and an OD trailing face located axially opposite the OD leading face, wherein the OD flow rail and the OD vane platform define a secondary airflow path, such that in use, cooling air flows through the secondary airflow path by passing through an aperture in the OD forward rail, through an aperture in the flow rail and over the OD aft rail, characterised in that the OD aft rail comprises an OD chamfered face extending from the OD leading face, wherein the OD chamfered face comprises a radially outer surface of the aft rail such that, in use, cooling air flows over the OD aft rail with minor interruption and/or impingement. a turbine section; an OD flow rail; and a stator vane assembly in the turbine section, the stator vane assembly comprising: a stator vane having a first end opposite a second end; an ID stator vane platform coupled to the first end; an OD stator vane platform coupled to the second end, wherein the OD stator vane platform comprises: an OD forward rail extending radially from the stator vane platform; and an OD aft rail extending radially from the stator vane platform and located axially opposite and aft of the OD forward rail, wherein the OD aft rail comprises: an OD axis defining a perpendicular direction relative to the OD aft rail; an OD leading face; and an OD trailing face located axially opposite the OD leading face, wherein the OD flow rail and the OD vane platform define a secondary airflow path, such that in use, cooling air flows through the secondary airflow path by passing through an aperture in the OD forward rail, through an aperture in the flow rail and over the OD aft rail, characterised in that the OD aft rail comprises an OD chamfered face extending from the OD leading face, wherein the OD chamfered face comprises a radially outer surface of the aft rail such that, in use, cooling air flows over the OD aft rail with minor interruption and/or impingement. a stator vane having a first end opposite a second end; an ID stator vane platform coupled to the first end; an OD stator vane platform coupled to the second end, wherein the OD stator vane platform comprises: an OD forward rail extending radially from the stator vane platform; and an OD aft rail extending radially from the stator vane platform and located axially opposite and aft of the OD forward rail, wherein the OD aft rail comprises: an OD axis defining a perpendicular direction relative to the OD aft rail; an OD leading face; and an OD trailing face located axially opposite the OD leading face, wherein the OD flow rail and the OD vane platform define a secondary airflow path, such that in use, cooling air flows through the secondary airflow path by passing through an aperture in the OD forward rail, through an aperture in the flow rail and over the OD aft rail, characterised in that the OD aft rail comprises an OD chamfered face extending from the OD leading face, wherein the OD chamfered face comprises a radially outer surface of the aft rail such that, in use, cooling air flows over the OD aft rail with minor interruption and/or impingement. an OD forward rail extending radially from the stator vane platform; and an OD aft rail extending radially from the stator vane platform and located axially opposite and aft of the OD forward rail, wherein the OD aft rail comprises: an OD axis defining a perpendicular direction relative to the OD aft rail; an OD leading face; and an OD trailing face located axially opposite the OD leading face, wherein the OD flow rail and the OD vane platform define a secondary airflow path, such that in use, cooling air flows through the secondary airflow path by passing through an aperture in the OD forward rail, through an aperture in the flow rail and over the OD aft rail, characterised in that the OD aft rail comprises an OD chamfered face extending from the OD leading face, wherein the OD chamfered face comprises a radially outer surface of the aft rail such that, in use, cooling air flows over the OD aft rail with minor interruption and/or impingement. an OD axis defining a perpendicular direction relative to the OD aft rail; an OD leading face; and an OD trailing face located axially opposite the OD leading face, wherein the OD flow rail and the OD vane platform define a secondary airflow path, such that in use, cooling air flows through the secondary airflow path by passing through an aperture in the OD forward rail, through an aperture in the flow rail and over the OD aft rail, characterised in that the OD aft rail comprises an OD chamfered face extending from the OD leading face, wherein the OD chamfered face comprises a radially outer surface of the aft rail such that, in use, cooling air flows over the OD aft rail with minor interruption and/or impingement.