Shear wave resistant flange assembly

A gas turbine engine comprising:

• a first engine case including a first body extending along an engine longitudinal axis from a first end portion to bound a gas path;
• a second engine case including a second body extending along the engine longitudinal axis from a second end portion to bound the gas path;
• a plurality of fasteners;
• wherein the first end portion includes a first flange having a plurality of mounting assemblies circumferentially distributed about the engine longitudinal axis, each of the mounting assemblies including a first aperture dimensioned to receive a respective one of the fasteners and a declined ramped surface that extends away from a first rim of the first aperture;
• wherein the second end portion includes a plurality of flanges circumferentially distributed about the engine longitudinal axis, each of the plurality of flanges defining a receptacle dimensioned to receive the first end portion, a second aperture dimensioned to receive a respective one of the fasteners and an inclined ramped surface that extends toward a second rim of the second aperture;
• and
• wherein the first engine case is moveable in an axial direction into each receptacle and is then rotatable in a circumferential direction about the engine longitudinal axis to interlock each of the plurality of mounting assemblies and a respective one of the plurality of flanges.

A method of assembly for a gas turbine engine comprising:

• a first annular case including a first body extending from a first end portion;
• a second annular case including a second body extending along a longitudinal axis from a second end portion;
• wherein the first end portion includes a first flange, the first flange including at least one mounting assembly, the at least one mounting assembly including a first aperture dimensioned to receive a fastener and a first ramped surface that extends axially from the first aperture;
• wherein the second end portion includes at least one flange defining a receptacle dimensioned to receive the first end portion, a second aperture dimensioned to receive the fastener and a second ramped surface;
• and
• wherein the first annular case is moveable in an axial direction relative to the longitudinal axis through an axial opening of the receptacle such that the first end portion is received in the receptacle, and is rotatable about the longitudinal axis to define an interface between the first and second ramped surfaces to interlock the first end portion in the receptacle and limit movement of the first annular case relative to the longitudinal axis;
• wherein the method comprises:
• moving the first flange along the longitudinal axis into the receptacle of the second flange;
• rotating the first annular case about the longitudinal axis such that the first ramped surface of the first flange abuts the second ramped surface of the receptacle to interlock the first and second annular cases;
• and
• mechanically attaching the first and second flanges with the fastener received in the first and second apertures of the first and second flanges, and wherein the first and second ramped surfaces slope from the respective apertures.