Abstract: High bypass ratio turbofan propulsion engines are designed with a two-step approach to surviving foreign object damage to the fan assembly. First, a containment system encircling the fan assembly to capture any part of a released fan blade in the event of damage occurring, and two in order to cope with the vibrations resulting from a rotating unbalanced fan assembly the support structure for the bearing of the rotating assembly is constructed with frangible parts to introduce a snubber gap to permit the rotating, unbalanced fan assembly and bearing to orbit thereby to reduce the resulting vibrations. However, in the case of very wide chord fan assemblies, the largest acceptable snubber gap is insufficient to reduce the induced vibrations.

Abstract: High bypass ratio turbofan propulsion engines are designed with a two-step approach to surviving foreign object damage to the fan assembly. First, a containment system encircling the fan assembly to capture any part of a released fan blade in the event of damage occurring, and two in order to cope with the vibrations resulting from a rotating unbalanced fan assembly the support structure for the bearing of the rotating assembly is constructed with frangible parts to introduce a snubber gap to permit the rotating, unbalanced fan assembly and bearing to orbit thereby to reduce the resulting vibrations. However, in the case of very wide chord fan assemblies, the largest acceptable snubber gap is insufficient to reduce the induced vibrations.

Abstract: A gas turbine engine rotor blade containment assembly (38) comprises a generally cylindrical, or frustoconical, metal casing (40). The metal casing (40) has at least one arched portion (62,64,66) and each arched portion (62,64,66) extends circumferentially around the metal casing (40). Each arched portion (62,64,66) comprises a radially inwardly extending arch (68) in which the trough (74) of the arch (68) is radially inwardly of a straight line (76) interconnecting the axial ends (70,72) of the arch (68). The trough (74) of the arch (68) is radially inwardly of the at least one of the axial ends (70,72) of the at least one arch (68). The arched portions (62,64,66) introduce compressive stresses into the metal casing (40) during a fan blade 34 impact and enable the metal casing (40) to withstand the impact. The fan blade containment assembly (38) is lighter for large diameter turbofan gas turbine engine (10).

Abstract: A gas turbine engine rotor blade containment assembly (38) comprises a generally cylindrical, or frustoconical, metal casing (40). The metal casing (40) has at least one arched portion (62, 64, 66) and each arched portion (62, 64, 66) extends circumferentially around the metal casing (40). Each arched portion (62, 64, 66) comprises a radially inwardly extending arch (68) in which the trough (74) of the arch (68) is radially inwardly of a straight line (76) interconnecting the axial ends (70, 72) of the arch (68). The trough (74) of the arch (68) is radially inwardly of the at least one of the axial ends (70, 72) of the at least one arch (68). The arched portions (62, 64, 66) introduce compressive stresses into the metal casing (40) during a fan blade 34 impact and enable the metal casing (40) to withstand the impact. The fan blade containment assembly (38) is lighter for large diameter turbofan gas turbine engine (10).

Abstract: An indentor for contacting a bearing surface, the indentor comprising a contact surface complimentary to that of the bearing surface, wherein the indentor comprises an integral tapering portion which tapering portion defines part of the contact surface, the tapering portion at its distal edge defining an edge of contact between the contact surface and the bearing surface.

Abstract: An indentor for contacting a bearing surface, the indentor comprising a contact surface complimentary to that of the bearing surface, wherein the indentor comprises an integral tapering portion which tapering portion defines part of the contact surface, the tapering portion at its distal edge defining an edge of contact between the contact surface and the bearing surface.

Abstract: A gas turbine engine rotor blade containment assembly (38) comprising a generally cylindrical, or frustoconical, first metal casing (40) and a plurality of generally cylindrical, or frustoconical axially spaced second metal casing is (54, 56 & 58). The second metal casings (54, 56, 58) surrounded and abut the first metal casing (40). The first metal casing (40) is relatively hard and tough to contain a fan blade (34). The second metal casings (54, 56, 58 are relatively soft and lightweight to stiffen the first metal casing (40) and fan blade containment regions (A, B & C). The second metal casing (54, 56, 58) are arranged coaxially with the first metal casing (40). One of the second metal casing means (56) is in a plane (Y) containing the fan blades (34) of the gas turbine engine (10). The first metal casing (40) comprises steel and the second metal casing is (54, 56, 58) comprise aluminum. The fan blade containment assembly (38) is lighter for large diameter turbofan gas turbine engine (10).

Abstract: A containment casing for a gas turbine engine comprising a substantially rigid casing shell arranged in operation coaxially with an axis of rotation of the gas turbine engine. The casing extending circumferentially around an array of fan rotor blades which are arranged to rotate about the engine axis. In the region of the casing where it is predicted blade impact in the event of a fan blade failure, there is at least one reinforcing rib extending substantially radially from the casing and circumscribing the outer periphery of the casing shell. The ribs providing improved strengthening of the casing. Preferably a first rib is positioned about the casing between the operational position of the trailing edge and the mid chord point of the fan blade. A second rib is axially positioned between the operational position of the mid chord point and the leading edge of the fan blade. A third rib may also be positioned axially forward of the operational position of the leading edge of the fan blade.