MID-TURBINE FRAME WITH INTERMEDIARY PLENUM

A gas turbine engine (10) has: a high-pressure turbine (18A); a low-pressure turbine (LPT) (18B) having a LPT outer case (36) and a LPT plenum (92) extending around a central axis (9); a mid-turbine frame (MTF) assembly (28) connecting the low-pressure turbine (18A) and the high-pressure turbine (18B), the MTF assembly (28) having: a MTF outer case (30) defining an inlet (84) for connection to a source of the cooling air, an intermediary plenum (93) fluidly connected to the source of cooling air via the inlet (84), the intermediary plenum (93) having a first air outlet (93B) and a second air outlet (93C), and a MTF plenum (60) disposed radially inwardly of the MTF outer case (30) and fluidly connected to the source of the cooling air via the first air outlet (93B) of the intermediary plenum (93); and a cooling air conduit (96) fluidly connecting the second air outlet (93C) of the intermediary plenum (93) to the LPT plenum (92) while bypassing the MTF plenum (60).