Abstract: A fan blade for a gas turbine engine has an aerofoil part and a root part. The root part includes a root former; the root former includes a zone of weakness, which reduces the ability of the root part to withstand an impact force. Thus, in an impact situation in which the fan blade has separated from the fan rotor and the fan blade has itself separated into fragments, the root part will fracture or buckle more easily than would be the case with conventional arrangements. This will lower the impact force of the root part upon the fan casing, thus permitting the fan casing to be designed to withstand lower impact forces. The fan casing can therefore be made lighter, and cheaper, than in conventional arrangements.

Abstract: International regulations for aerofoils within gas turbine engines require the safe containment of a released aerofoil. The blade fragments must be contained within an engine casing. Smaller fragments will generally be easier to contain within the casing and therefore reduce the weight of that casing. However introducing lines of weakness may result in cavities and holes which are subject to moisture ingress and problems associated therewith. By providing a root section which incorporates a core having shear surfaces, blades can be designed which in normal use are subject to compressive loads and remain operational, but when subject to impact loads or bending forces create tension forces which cause fragmentation along the shear surfaces after initial energy losses by slippage. By providing the shear surfaces in cores their location is encapsulated avoiding problems with moisture ingress.

Abstract: A fan blade for a gas turbine engine has an aerofoil part and a root part. The root part includes a root former; the root former includes a zone of weakness, which reduces the ability of the root part to withstand an impact force. Thus, in an impact situation in which the fan blade has separated from the fan rotor and the fan blade has itself separated into fragments, the root part will fracture or buckle more easily than would be the case with conventional arrangements. This will lower the impact force of the root part upon the fan casing, thus permitting the fan casing to be designed to withstand lower impact forces. The fan casing can therefore be made lighter, and cheaper, than in conventional arrangements.

Abstract: A fan blade for a gas turbine engine has an aerofoil part and a root part. The root part includes a root former; the root former 18 includes a zone of weakness, which reduces the ability of the root part to withstand an impact force. Thus, in an impact situation in which the fan blade has separated from the fan rotor and the fan blade has itself separated into fragments, the root part will fracture or buckle more easily than would be the case with conventional arrangements. This will lower the impact force of the root part upon the fan casing, thus permitting the fan casing to be designed to withstand lower impact forces. The fan casing can therefore be made lighter, and cheaper, than in conventional arrangements.

Abstract: Blade assemblies are provided in a number of forms. These blade assemblies may have blades secured to disks (blisk), rings (bling) and drums (blum). The blades and/or the rotor elements formed by these rings, drums or disks can fragment and it is necessary to contain such fragments within a casing. Impact energy has a significant effect upon the necessary thickness of the casing to ensure containment. By providing blades as well as rotor elements which incorporate discontinuities which provide flexing under impact, energy is absorbed prior to further fragmentation upon impact engagement with a casing surface; flexing is about the discontinuity. In such circumstances casings may be thinner and therefore significant weight savings achieved with regard to aircraft incorporating gas turbine engines having blade assemblies with discontinuities.

Abstract: A blade assembly for a rotary component comprises an aerofoil member and a displacement apparatus on the aerofoil member for displacing a detached first portion of the aerofoil member in a rearward direction relative to a second portion of the aerofoil member. On failure of the aerofoil member, the displacement apparatus displaces the first portion from the second portion in the rearward direction.

Abstract: A fan blade for a gas turbine engine has an aerofoil part and a root part. The root part includes a root former; the root former 18 includes a zone of weakness, which reduces the ability of the root part to withstand an impact force. Thus, in an impact situation in which the fan blade has separated from the fan rotor and the fan blade has itself separated into fragments, the root part will fracture or buckle more easily than would be the case with conventional arrangements. This will lower the impact force of the root part upon the fan casing, thus permitting the fan casing to be designed to withstand lower impact forces. The fan casing can therefore be made lighter, and cheaper, than in conventional arrangements.

Abstract: Blade assemblies are provided in a number of forms. These blade assemblies may have blades secured to disks (blisk), rings (bling) and drums (blum). The blades and/or the rotor elements formed by these rings, drums or disks can fragment and it is necessary to contain such fragments within a casing. Impact energy has a significant effect upon the necessary thickness of the casing to ensure containment. By providing blades as well as rotor elements which incorporate discontinuities which provide flexing under impact, energy is absorbed prior to further fragmentation upon impact engagement with a casing surface; flexing is about the discontinuity. In such circumstances casings may be thinner and therefore significant weight savings achieved with regard to aircraft incorporating gas turbine engines having blade assemblies with discontinuities.

Abstract: International regulations for aerofoils within gas turbine engines require the safe containment of a released aerofoil. The blade fragments must be contained within an engine casing. Smaller fragments will generally be easier to contain within the casing and therefore reduce the weight of that casing. However introducing lines of weakness may result in cavities and holes which are subject to moisture ingress and problems associated therewith. By providing a root section which incorporates a core having shear surfaces, blades can be designed which in normal use are subject to compressive loads and remain operational, but when subject to impact loads or bending forces create tension forces which cause fragmentation along the shear surfaces after initial energy losses by slippage. By providing the shear surfaces in cores their location is encapsulated avoiding problems with moisture ingress.

Abstract: A blade assembly for a rotary component comprises an aerofoil member and a displacement apparatus on the aerofoil member for displacing a detached first portion of the aerofoil member in a rearward direction relative to a second portion of the aerofoil member. On failure of the aerofoil member, the displacement apparatus displaces the first portion from the second portion in the rearward direction.