Key washer for a gas turbine engine

A method of redirecting a flow in a gas turbine engine, the method comprising:

• directing a first flow through a first flow path of a first turbine disc along an axis of the gas turbine engine;
• directing a second flow through a second flow path of the first turbine disc inward the first flow path relative to the axis, and along the axis;
• and
• deflecting the first flow downstream of the first turbine disc to direct the first flow toward the second flow downstream of the first turbine disc.

A washer for a gas turbine engine, the washer comprising:

• a first ring portion includes an annular ridge extending from an upstream surface of the first ring portion along a washer axis;
• at least one first keying feature extending outwardly from a peripheral surface of the first ring portion;
• at least one second keying feature of the annular ridge extending from the upstream surface of the first ring portion transverse to the peripheral surface;
• and
• a second ring portion radially inward of the first ring portion, the second ring portion defining a deflector surface transverse to the washer axis, the deflector surface having an upstream boundary flush with the annular ridge and extending from the upstream boundary to a downstream boundary so as to ramp away from the annular ridge toward the washer axis, the downstream boundary of the deflector surface forming an apex of the deflector surface.