Abstract: A cast and hot isostatically pressed gamma titanium aluminide turbine blade (26) has an aerofoil portion (38) including a concave pressure surface (44) and a convex suction surface (46). The concave pressure surface (44) has surface irregularities (48), produced by the action of the hot isostatic pressing process on voids (56) located within the cast turbine blade (26), located in that region (50) of the concave pressure surface (44) where in operation aerodynamic separation (G) occurs to minimise the aerodynamic effects of the surface irregularities (48) upon the operation of the turbine blade (26). The remaining portion of the concave pressure surface (44) and the whole of the convex suction surface (46) are substantially free of surface irregularities (48).

Abstract: A damper for damping non-synchronous vibration in adjacent shrouded aerofoil blades is in the form of pin which locates in confronting passages in adjacent blade shrouds. The pin is provided with larger diameter portions which are located totally within the passages and frictionally engage the surfaces of the passages to provide vibration damping. The larger diameter pin portions are interconnected by a central, thinner portion. The configuration of the pin reduces the likelihood of it wearing in such a manner that it jams in the passages and no longer provides vibration damping.

Abstract: A cast and hot isostatically pressed gamma titanium aluminide turbine blade has an aerofoil portion including a concave pressure surface and a convex suction surface. The concave pressure surface has surface irregularities, produced by the action of the hot isostatic pressing process on voids located within the cast turbine blade, located in that region of the concave pressure surface where in operation aerodynamic separation occurs to minimise the aerodynamic effects of the surface irregularities upon the operation of the turbine blade. The remaining portion of the concave pressure surface and the whole of the convex suction surface are substantially free of surface irregularities.

Abstract: An aerofoil blade containment structure that is adapted to surround the low pressure turbine casing of a gas turbine engine includes an annular support member upon which is mounted a glass fiber knitted sleeve. The knitted sleeve is folded to define a plurality of interconnected secondary sleeves that are arranged in coaxial superposed relationship. Use of the containment structure obviates the use of thick, and therefore undesirably heavy, turbine casings.

Abstract: The low pressure turbine of a gas turbine engine has an array of rotor blades and a shroud which surrounds the blade tips. The shroud is made up of a plurality of segments which are pivotally mounted from the turbine casing at their midpoints. The upstream portions of the shroud segments are fixed to the casing so that localised cooling of the casing in the region of pivotal attachment of the shroud segments causes the shroud segments to tilt and thereby improve the gas seal between the tips of the rotor blades and the shroud segments.

Abstract: An aerofoil balde rotor assembly in which a plurality of aerofoil blades having circumferentially extending platforms are located on the periphery of a rotatable disc. Each of the platforms is provided with tracks on its radially inner surface. The tracks of adjacent platforms define a convergent seating for a ceramic spherical damping member. Each spherical damping member frictionally engages the tracks of adjacent platforms simultaneously upon rotation of the assembly so as to provide aerofoil damping.

Abstract: A cooled turbine blade is provided with an aerofoil which tapers from root end to tip end so that the thicker root section provides greater resistance to detachment of the aerofoil. In order to provide effective cooling and light weight the aerofoil has a central `dead` cavity which extends from its root and part way up the aerofoil. Spanwise cooling passages bifurcate to pass between the cavity and the side walls in the relatively constant metal thickness thus provided.

Abstract: An aerofoil, particularly a nozzle guide vane, for a gas turbine engine comprises a hollow interior with an air guide tube located therein. The air guide tube has apertures therein, and in order to cause the free edges of the apertures to seal against internal ribs of the aerofoil, springs are provided to force the open edges apart. Conveniently the springs comprise straps between the apertures which are formed with a corrugated shape.

Abstract: A cooled rotor blade for a gas turbine has an aerofoil in which there are longitudinally extending cooling fluid passages. At the tip of the aerofoil is located a separate, chordwise extending tube. The tube has apertures in its wall which correspond with at least some of the cooling fluid passages, whereby the spent cooling fluid from these passages may pass through the tube to rejoin the gas flow of the engine.

Abstract: A fuel system is provided with two filters between the L.P. pump and the H.P. pump, both of which are used (in parallel) when the temperature of the L.P. fuel is above 0.degree. C. When the temperature of the fuel drops below 0.degree. C., all the L.P. fuel is passed through the first filter, and a small supply of warm H.P. fuel is passed through the second filter. Ice collects in the first filter until a predetermined pressure drop across it causes all the L.P. fuel flow to be switched to the second filter. The first filter is then de-iced by a small supply of warm H.P. fuel. This cycle is repeated continuously while the temperature of the L.P. fuel is below 0.degree. C.

Abstract: A hollow blade or vane for a gas turbine engine is provided with a longitudinally extending, hollow thickened portion in its wall adjacent the leading edge. This hollow thickened portion acts as an integral strut and relieves the leading edge of some loads.