A gas turbine engine blade containment assembly

A gas turbine engine fan blade containment assembly (38) comprising a generally cylindrical, or frustoconical, metal casing (40) has an upstream portion (56), a transition portion (58) and a blade containment portion (54). The upstream portion (56) has a flange (42) connecting the metal casing (40) to a flange (48) on axially adjacent casing (46). The blade containment portion (54) has a greater thickness (T2) than the thickness (T1) of the upstream portion (54). The transition portion (58) connects the blade containment portion (54) and the upstream portion (56) to transmit loads from the blade containment portion (54) to the flange (42) on the upstream portion (56). The ratio of the thickness (T4) of the flange (42) on the upstream portion (56) to the thickness (T1) of the upstream portion (56) is between 3 to 1 and 6 to 1. The flange (42) on the upstream portion (56) is radially scalloped (41) between adjacent fasteners (49,51) and the upstream portion (54) is relatively thin such that the flange (42) and upstream portion (56) are allowed to deform to reduce impact loads transmitted to the flange (48) on the casing (46).