Abstract: Aspects of the disclosure are directed to a system comprising: a fastener that includes: a head that includes a feature pattern to accommodate installation and removal of the fastener, where the feature pattern is biased to provide a first torque capability in the installation of the fastener and a second torque capability in the removal of the fastener, and where the second torque capability is greater than the first torque capability.

Abstract: A turbofan engine comprises an engine case. A gaspath extends through the engine case. A fan has a circumferential array of fan blades. A fan case encircles the fan blades radially outboard of the engine case. A plurality of fan case vanes extend aftward and outward from the engine case to the fan case. A forward frame comprises a plurality of vanes radially across the gaspath. A torque box couples the fan case vanes to the forward frame. A transmission couples a shaft to a fan shaft to drive the fan. A fan bearing assembly couples a stationary forward hub structure to the fan shaft.

Abstract: Independent axial preloading of compressor and turbine disks in a gas turbine engine rotor is achieved by a dual tie shaft arrangement wherein a forward tie shaft engages forward and aft portions of a compressor hub within which the compressor disks are disposed to axially and compressively preload the compressor disks between the forward and aft portions of the compressor hub. An independent tie shaft engages an aft portion of a turbine hub within which turbine disks are disposed and an aft portion of the compressor hub to axially and compressively preload the turbine disks between the turbine and compressor hubs.

Abstract: A turbofan engine comprises an engine case. A gaspath extends through the engine case. A fan has a circumferential array of fan blades. A fan case encircles the fan blades radially outboard of the engine case. A plurality of fan case vanes extend aftward and outward from the engine case to the fan case. A forward frame comprises a plurality of vanes radially across the gaspath. A torque box couples the fan case vanes to the forward frame. A transmission couples a shaft to a fan shaft to drive the fan. A fan bearing assembly couples a stationary forward hub structure to the fan shaft.

Abstract: Independent axial preloading of compressor and turbine disks in a gas turbine engine rotor is achieved by a dual tie shaft arrangement wherein a forward tie shaft engages forward and aft portions of a compressor hub within which the compressor disks are disposed to axially and compressively preload the compressor disks between the forward and aft portions of the compressor hub. An independent tie shaft engages an aft portion of a turbine hub within which turbine disks are disposed and an aft portion of the compressor hub to axially and compressively preload the turbine disks between the turbine and compressor hubs.

Abstract: A variable vane mechanism comprises a variable vane, an inner diameter shroud and a synchronizing mechanism. The variable vane comprises a vane body, an inner diameter trunnion extending radially inwardly from the vane body, and a button connected to the inner diameter trunnion and displaced radially inwardly from the inner diameter trunnion. The shroud comprises a shroud body, a socket extending into the shroud body for receiving the inner diameter trunnion, a flange extending into the socket for engaging the button and inhibiting radial movement of the variable vane, and a synchronizing channel extending through the inner diameter shroud aft of the socket so as to be bounded by the shroud body and opening to the socket. The synchronizing mechanism is disposed inside the synchronizing channel and connects to the inner diameter trunnion.

Abstract: An inner diameter vane shroud for use in a gas turbine engine is comprised of lightweight cast forward and aft shroud components. The forward and aft shroud components are made with an investment casting technique that creates a hollow cavity that runs in a circumferential direction through each component. The forward and aft shroud components are matable to form sockets that receive inner diameter ends of variable stator vanes.

Abstract: A variable vane actuation mechanism is comprised of a first drive vane arm and a second drive vane arm for driving a first variable vane array and a second variable vane array, respectively, of a stator vane section of a gas turbine engine. The first drive vane arm and second drive vane arm are connected to each other at a first end by a linkage. The first drive vane arm and second drive vane arm are connected at a second end to a first drive vane and a second drive vane, respectively, of the first and second variable vane arrays. The first drive vane arm and second drive vane arm respond in unison to a single actuation source connected to one of the first drive vane arm and second drive vane arm.

Abstract: An inner diameter vane shroud of a variable vane assembly accommodates a synchronization mechanism for coordinating rotation of an array of variable vanes. The inner diameter vane shroud has a gear track that runs circumferentially through the vane shroud. An array of variable vanes is rotatably mounted in the vane shroud at an inner end. Each vane has a gear pinion at its inner end, which interfaces with the gear track. As one of the individual variable vanes is rotated by an actuation source, the other variable vanes of the variable vane array are rotated a like amount by the rack and pinion gear interface.

Abstract: An inner diameter vane shroud accommodates a mechanism for synchronously rotating an away of variable vanes. Particularly, the inner diameter vane shroud has a gear channel that runs circumferentially through the vane shroud. An array of variable vanes is rotatably mounted in the vane shroud at an inner end. The variable vanes comprise vane gears at their inner end, which are rotatable in the gear channel. Disposed between the vane gears of the variable vanes are idler gears. As one of the individual variable vanes is rotated by an actuation source, the other variable vanes of the variable vane away are rotated a like amount by the vane gears and idler gears.

Abstract: A variable vane mechanism comprises a variable vane, an inner diameter shroud and a synchronizing mechanism. The variable vane comprises a vane body, an inner diameter trunnion extending radially inwardly from the vane body, and a button connected to the inner diameter trunnion and displaced radially inwardly from the inner diameter trunnion. The shroud comprises a shroud body, a socket extending into the shroud body for receiving the inner diameter trunnion, a flange extending into the socket for engaging the button and inhibiting radial movement of the variable vane, and a synchronizing channel extending through the inner diameter shroud aft of the socket so as to be bounded by the shroud body and opening to the socket. The synchronizing mechanism is disposed inside the synchronizing channel and connects to the inner diameter trunnion.

Abstract: A variable vane assembly includes a sync ring mechanism for synchronously rotating an array of variable vanes. The variable vane assembly comprises a drive vane, a synch ring, a vane arm and a plurality of follower vanes and follower arms. An inner diameter end of the drive vane rotates in an inner diameter vane shroud. The synch ring rotates in an inner channel of the inner diameter vane shroud. The vane arm connects the inner diameter end of the drive vane with the synch ring. The plurality of follower vanes are connected to the synch ring by the follower arms. When the drive vane is rotated by an actuation source, the plurality of follower vanes rotate a like amount by the synch ring and follower arms.