Air-oil separator with first separator radially outward of matrix separator

A gas turbine engine having a shaft, the gas turbine engine comprising an air-oil separator secured to the shaft for rotation about a rotation axis, the air-oil separator having:

• a first separator rotatable about the rotation axis and configured to separate an air-oil mixture having a first oil concentration;
• and a matrix separator rotatable about the rotation axis and configured to separate an air-oil mixture having a second oil concentration less than the first oil concentration, the matrix separator having a porous media, the matrix separator disposed at least partially concentrically within the first separator, one of the first separator and the matrix separator disposed around the other of the first separator and the matrix separator, the air-oil separator defining a flow path extending from an air-oil mixture inlet of the first separator to an air outlet of the air-oil separator, the flow path extending in a radial direction relative to the rotation axis when passing from the first separator to the matrix separator through at least one radial passage fluidly connecting the first separator to the matrix separator, the radial passage extending through a wall disposed radially between the first and matrix separators, at least one passage extending radially outwardly from the matrix separator across the first separator, the at least one passage fluidly connecting the matrix separator to an environment outside the air-oil separator.