Abstract: A gas turbine engine has a core frame separable from a vane frame for removably attaching the vane frame to a core structure through a mid ring. The mid ring includes an annular forward panel and an annular aft panel, each of which has a radially outer flange and a radially inner flange. The inner flanges are welded to the core frame and the outer flanges are bolted to the vane frame. A plurality of circumferentially spaced stiffeners extend between the forward and aft panels, with each of the stiffeners including a pair of stringers extending diagonally across the stiffeners. Panels may be incorporated with the stringers between the triangular shaped areas adjacent the forward and aft panels of the stiffener. The bolted connection between the mid ring and the vane frame includes a plurality of tongue and groove joints formed in the flanges of the mid ring and vane frame. The tongue and groove joints provide additional radial support for the core engine within the vane frame.