Abstract: A system is provided in one example embodiment and may include a first reservoir for a lubricant; a second reservoir for the lubricant, wherein the first reservoir and the second reservoir are interconnected; a first pumping element to pump the lubricant from the first reservoir at a first flow rate; a second pumping element to pump the lubricant at a second flow rate, wherein the first flow rate and the second flow rate are different; and a gearbox coupled to the first pumping element and the second pumping element. The first reservoir may have a larger volume than the second reservoir and the first flow rate may be higher than the second flow rate.

Abstract: A selectable clutch assembly for a multimode powertrain of a rotorcraft. The selectable clutch assembly includes a freewheeling unit having input and output sides. The freewheeling unit has a driving mode wherein torque applied to the input side is transferred to the output side and an over running mode wherein torque applied to the output side is not transferred to the input side. A bypass assembly is coupled to and rotatable with the output side of the freewheeling unit and is actuatable between engaged and disengaged positions with the input side of the freewheeling unit. In the disengaged position, the freewheeling unit is operable in the driving and the over running modes such that the selectable clutch assembly is configured for unidirectional torque transfer. In the engaged position, the over running mode of the freewheeling unit is disabled such that the selectable clutch assembly is configured for bidirectional torque transfer.

Abstract: A selectable clutch assembly for a multimode powertrain of a rotorcraft. The selectable clutch assembly includes a freewheeling unit having input and output sides. The freewheeling unit has a driving mode wherein torque applied to the input side is transferred to the output side and an over running mode wherein torque applied to the output side is not transferred to the input side. A bypass assembly is coupled to and rotatable with the output side of the freewheeling unit and is actuatable between engaged and disengaged positions with the input side of the freewheeling unit. In the disengaged position, the freewheeling unit is operable in the driving and the over running modes such that the selectable clutch assembly is configured for unidirectional torque transfer. In the engaged position, the over running mode of the freewheeling unit is disabled such that the selectable clutch assembly is configured for bidirectional torque transfer.

Abstract: A method for calculating torque through a rotor mast of a propulsion system of a tiltrotor aircraft includes receiving the torque being applied through a quill shaft of the rotorcraft. The quill shaft is located between a fixed gearbox and a spindle gearbox, and the spindle gearbox is rotatable about a conversion access. The torque through the rotor mast is determined by using the torque through the quill shaft and the efficiency loss value between the quill shaft and the rotor mast.

Abstract: A system is provided in one example embodiment and may include a first reservoir for a lubricant; a second reservoir for the lubricant, wherein the first reservoir and the second reservoir are interconnected; a first pumping element to pump the lubricant from the first reservoir at a first flow rate; a second pumping element to pump the lubricant at a second flow rate, wherein the first flow rate and the second flow rate are different; and a gearbox coupled to the first pumping element and the second pumping element. The first reservoir may have a larger volume than the second reservoir and the first flow rate may be higher than the second flow rate.

Abstract: A tiltrotor aircraft can include a pylon rotatable about a conversion axis. A first differential planetary assembly can include a first housing; a first ring gear; a first differential planetary gear having a first output portion; and a first differential sun gear. A second differential planetary assembly can include a second housing; a second ring gear; a second differential planetary gear having a second output portion; and a second differential sun gear. The first output portion is coupled to the second housing such that the second housing rotates at a first output speed. Further, the second output portion is coupled to the shaft, the shaft being coupled to the pylon such that rotation of the shaft rotates the pylon.

Abstract: A method for calculating torque through a rotor mast of a propulsion system of a tiltrotor aircraft includes receiving the torque being applied through a quill shaft of the rotorcraft. The quill shaft is located between a fixed gearbox and a spindle gearbox, and the spindle gearbox is rotatable about a conversion access. The torque through the rotor mast is determined by using the torque through the quill shaft and the efficiency loss value between the quill shaft and the rotor mast.

Abstract: A method for calculating torque through a rotor mast of a propulsion system of a tiltrotor aircraft includes receiving the torque being applied through a quill shaft of the rotorcraft. The quill shaft is located between a fixed gearbox and a spindle gearbox, and the spindle gearbox is rotatable about a conversion access. The torque through the rotor mast is determined by using the torque through the quill shaft and the efficiency loss value between the quill shaft and the rotor mast.

Abstract: A quill shaft is configured for transferring torque and accepting misalignments between a fixed gearbox and a rotatable spindle gearbox in a propulsion system of a tiltrotor aircraft, the quill shaft includes a first splined portion configured for coupling to an output gear of the fixed gearbox, and a second splined portion configured for coupling to an input gear of the spindle gearbox. The spindle gearbox includes a rotor mast associated therewith, the spindle gearbox being rotatable so that the tiltrotor aircraft can selectively operate in a helicopter mode and airplane mode.

Abstract: A support assembly for coupling a first gearbox to an airframe of an aircraft. The first gearbox has an output gear operable to transfer torque to an input gear of a second gearbox via a common shaft rotatable about a longitudinal axis. The support assembly includes a fixed joint proximate the longitudinal axis. A first directional reacting joint remote from the longitudinal axis provides a first radial growth degree of freedom to the first gearbox relative to the longitudinal axis. A second directional reacting joint remote from the longitudinal axis provides a second radial growth degree of freedom to the first gearbox relative to the longitudinal axis. The first radial growth degree of freedom is not parallel with the second radial growth degree of freedom such that the support assembly maintains the output gear of the first gearbox in substantial collinear alignment with the input gear of the second gearbox.

Abstract: A support assembly for coupling a first gearbox to an airframe of an aircraft. The first gearbox has an output gear operable to transfer torque to an input gear of a second gearbox via a common shaft rotatable about a longitudinal axis. The support assembly includes a fixed joint proximate the longitudinal axis. A first directional reacting joint remote from the longitudinal axis provides a first radial growth degree of freedom to the first gearbox relative to the longitudinal axis. A second directional reacting joint remote from the longitudinal axis provides a second radial growth degree of freedom to the first gearbox relative to the longitudinal axis. The first radial growth degree of freedom is not parallel with the second radial growth degree of freedom such that the support assembly maintains the output gear of the first gearbox in substantial collinear alignment with the input gear of the second gearbox.

Abstract: A drive system for a tiltrotor aircraft includes a first gearbox rotatably mounted to the airframe and rotatable about a longitudinal axis to operate the tiltrotor aircraft between helicopter and airplane modes. A second gearbox extends generally normal to the longitudinal axis of the first gearbox. A common shaft, rotatable about the longitudinal axis, transfers torque from an output gear of the second gearbox to an input gear of the first gearbox. A support assembly couples the second gearbox to the airframe and includes a fixed joint proximate the longitudinal axis, a first directional reacting joint remote from the longitudinal axis providing a first radial growth degree of freedom to the second gearbox and a second directional reacting joint remote from the longitudinal axis providing a second radial growth degree of freedom to the second gearbox that is not parallel with the first radial growth degree of freedom.

Abstract: A drive system for a tiltrotor aircraft includes a first gearbox rotatably mounted to the airframe and rotatable about a longitudinal axis to operate the tiltrotor aircraft between helicopter and airplane modes. A second gearbox extends generally normal to the longitudinal axis of the first gearbox. A common shaft, rotatable about the longitudinal axis, transfers torque from an output gear of the second gearbox to an input gear of the first gearbox. A support assembly couples the second gearbox to the airframe and includes a fixed joint proximate the longitudinal axis, a first directional reacting joint remote from the longitudinal axis providing a first radial growth degree of freedom to the second gearbox and a second directional reacting joint remote from the longitudinal axis providing a second radial growth degree of freedom to the second gearbox that is not parallel with the first radial growth degree of freedom.

Abstract: A rotor system for tilt rotor aircraft comprises an engine disposed at a first fixed position on a wing member, and a prop-rotor pylon mechanically coupled to the engine along a drive path extending through the wing member. The engine is disposed adjacent a fuselage of the tilt rotor aircraft, and the prop-rotor pylon is configured to selectively rotate between a vertical position and a horizontal position. The prop-rotor pylon is coupled to a plurality of rotor blades.

Abstract: A method for calculating torque through a rotor mast of a propulsion system of a tiltrotor aircraft includes receiving the torque being applied through a quill shaft of the rotorcraft. The quill shaft is located between a fixed gearbox and a spindle gearbox, and the spindle gearbox is rotable about a conversion access. The torque through the rotor mast is determined by using the torque through the quill shaft and the efficiency loss value between the quill shaft and the rotor mast.

Abstract: A tiltrotor aircraft can include a pylon rotatable about a conversion axis. A first differential planetary assembly can include a first housing; a first ring gear; a first differential planetary gear having a first output portion; and a first differential sun gear. A second differential planetary assembly can include a second housing; a second ring gear; a second differential planetary gear having a second output portion; and a second differential sun gear. The first output portion is coupled to the second housing such that the second housing rotates at a first output speed. Further, the second output portion is coupled to the shaft, the shaft being coupled to the pylon such that rotation of the shaft rotates the pylon.

Abstract: A tiltrotor aircraft includes a fuselage; a wing member having a first rib, a second rib, a first spar, second spar; and an upper wing skin; an engine disposed at a fixed location relative to the wing member; and a proprotor having a spindle gearbox, rotor mast, and a plurality of rotor blades drivable in rotation about the rotor mast, the spindle gearbox being rotatable about a conversion axis. The spindle gearbox is located above the upper wing skin of the wing member.

Abstract: A rotor system for tilt rotor aircraft comprises an engine disposed at a first fixed location on a wing member; a prop-rotor pylon mechanically coupled to the engine along a drive path, and a gearbox disposed in the drive path. The prop-rotor pylon is rotatably mounted on a spindle, and the prop-rotor pylon is configured to selectively rotate about a rotational axis of the spindle between a vertical position and a horizontal position. The gearbox comprises a rotational axis aligned with the rotational axis of the spindle.

Abstract: A tiltrotor aircraft includes a fuselage; a wing member having a first rib, a second rib, a first spar, second spar; and an upper wing skin; an engine disposed at a fixed location relative to the wing member; and a proprotor having a spindle gearbox, rotor mast, and a plurality of rotor blades drivable in rotation about the rotor mast, the spindle gearbox being rotatable about a conversion axis. The spindle gearbox is located above the upper wing skin of the wing member.

Abstract: A quill shaft is configured for transferring torque and accepting misalignments between a fixed gearbox and a rotatable spindle gearbox in a propulsion system of a tiltrotor aircraft, the quill shaft includes a first splined portion configured for coupling to an output gear of the fixed gearbox, and a second splined portion configured for coupling to an input gear of the spindle gearbox. The spindle gearbox includes a rotor mast associated therewith, the spindle gearbox being rotatable so that the tiltrotor aircraft can selectively operate in a helicopter mode and airplane mode.