Abstract: A brake unit comprises said rotor disc rotatable about a central axis of rotation and a first brake pad mounting element having a first end and a second end and a longitudinal outer, side, surface extending there between, wherein a first brake pad is provided at said first end of said first brake pad mounting element and positioned facing a first face of said rotor disc. The first brake pad mounting element comprises a first locking feature provided on its outer, side, surface. The brake unit further comprises first locking element that pivots about pivot and that is movable about said pivot axis so that a locking feature of said locking element can come into contact with, or be moved away from said outer, side, surface of said first brake pad mounting element.

Abstract: A nut arrangement for a screw actuator is disclosed for allowing detection of wear in a primary nut of the screw actuator. The nut arrangement comprises a primary nut for providing a primary load path and a secondary nut for providing a secondary load path. An interface ring may link the secondary nut to the primary nut. A sensor is provided to detect relative axial movement between the primary and secondary nuts. During normal operation, the interface ring is seated by a flexible coupling that allows relative axial displacement of the secondary nut to the primary nut to accommodate wear in the primary nut. The sensor can be used to monitor backlash between the primary and secondary nuts to determine wear of the primary nut.

Abstract: A method for monitoring the health of propellers in an aircraft is provided. The method includes receiving pressure waves generated by at least one rotating propeller and analysing data corresponding to the received pressure waves to detect tonal noise which is within a selected frequency range. If tonal noise at harmonics of the propeller rotational frequency within the selected frequency range is detected within the selected frequency range, it is established that the health of at least one propeller may be impaired and an alert is created for inspection and maintenance to take place.

Abstract: A propeller component, for example a propeller blade airfoil, includes an external surface exposed in use to an oncoming airstream (A), and a protective polymeric film applied over substantially the entire exposed external surface of the component.

Abstract: A method of monitoring the health of an aircraft propeller whilst the propeller is in operation, the propeller having a plurality of blades extending radially outwardly from a central axis extending through the propeller and a propeller drive shaft, is provided. The method includes obtaining measurements representative of strain in the propeller drive shaft using multiple primary strain sensors, each primary strain sensor providing respective measurements representative of strain. The primary strain sensors are located around a circumference of the drive shaft of the propeller, and each strain sensor is located such that it crosses a plane defined by the radial direction of a blade and the central axis, the plane being bounded by the central axis. A corresponding propeller health monitoring system, an aircraft propeller comprising the system and an aircraft comprising the propeller are also provided.

Abstract: A transmission or gearbox assembly with fail-safe means for providing redundancy where failure can lead to loss of torque transmission between component parts of the assembly, the assembly comprising a plurality of first components in torque transmitting engagement and at least one second component associated with at least one of the first components, the second component being joined to the respective first component by a discontinuous joint. Preferably, each first component of the system has a corresponding second component joined thereto by a discontinuous joint.

Abstract: A method is disclosed for manufacture of a composite blade with an airfoil and a root, wherein the blade comprises a core of chopped fibre composite material and a textile composite material encasing the chopped fibre core. The method comprises: forming a blade insert using chopped fibre composite; surrounding the blade insert with a plurality of layers of a textile in a textile composite material; and thermoforming the blade insert and the surrounding textile composite material in a thermoforming mould in order to consolidate the part.

Abstract: A propeller hydraulic actuation system, includes a double-acting dual chamber hydraulic pitch change actuator. The pitch change actuator includes a first pressure circuit having first fluid supply lines and a first hydraulic chamber and a second pressure circuit having second fluid supply lines and a second hydraulic chamber. A piston separates the first and second chambers. At least one pressure sensor is provided for obtaining pressure measurements from which a load differential (F) applied to the piston by the circuits can be calculated. A closed loop controller is arranged to control the fluid supplied to the first and second pressure circuits, wherein the closed loop controller includes an actuator position loop arranged to utilise feedback on the actuator position to control the actuator position.

Abstract: A valve comprises a valve seat and a rotary valve element. The valve seat comprises a valve opening having a sealing surface. The valve element is mounted with respect to said valve seat for rotation about an axis of rotation between a closed position in which the valve element substantially closes the valve opening and an open position in which the valve element permits flow through the valve opening. The valve opening is elliptical in shape, having spaced apart upper and lower edges the upper and lower edges being generated as respective ellipses formed by parallel sections through a conical surface. The valve seat sealing surface is defined between said upper and lower edges.

Abstract: An actuator is disclosed comprising: a moveable member; a first hydraulic chamber in contact with a first surface of the moveable member; a second hydraulic chamber in contact with a second, opposing surface of the moveable member; a movable locking mechanism coupled to a moveable wall of the second hydraulic chamber; and a resilient biasing member acting on the moveable wall of the second hydraulic chamber so as to bias the moveable wall and locking mechanism. The actuator is configured to selectively vary the pressure in the second hydraulic chamber so that the resilient biasing member is able to bias the moveable wall to move, thereby moving the locking mechanism to engage the moveable member so as to prevent the movement of the moveable member towards at least one of the first and second hydraulic chambers.

Abstract: Disclosed herein is a hydraulic actuator system comprising a servoactuator including a hydraulic actuator and a control valve, wherein the supply of hydraulic fluid to the servoactuator from a fluid supply is adjustable through a control system based on feedback information relating to the servoactuator. The hydraulic actuator system may e.g. be used for controlling blade pitch in a variable pitch propeller system such as may be found on a turboprop aircraft or a ship.

Abstract: A method for monitoring the health of propellers in an aircraft is provided. The method includes receiving a first propeller pitch angle of a first propeller of an aircraft; calculating a first residual pitch angle which is the difference between the first propeller pitch angle and a second propeller pitch angle; and comparing the first residual pitch angle to at least one threshold. The at least one threshold may include upper and lower thresholds. It is established that the health of the propeller may be impaired if the residual pitch angle is outside the at least one threshold, for example it exceeds the upper threshold or is below the lower threshold. If it is established that the health of the propeller may be impaired, an alert is made for inspection and maintenance to take place.

Abstract: An hydraulic actuation control module is provided for installation in a pitch change actuator of a propeller assembly. The module comprises a flow metering valve arranged to supply hydraulic fluid flow and pressure to an actuator and an electronic control unit arranged to control the flow metering valve. The flow metering valve is arranged to meter hydraulic fluid flow and pressure to increase and decrease pitch chambers of the pitch change actuator, in accordance with the control of the electronic control unit. The flow metering valve is arranged to receive an hydraulic fluid supply from an entity relative to which the propeller assembly rotates such as an engine driving the propeller assembly or aircraft on which the propeller assembly is installed. A propeller assembly comprising the hydraulic actuation control module is also disclosed, together with a method of installing the module within a propeller assembly.

Abstract: A failsafe bar connection of a screw actuator includes a failsafe bar for transmitting load via a secondary load path, the failsafe bar having a bar-end with a convex thrust surface; and an attachment part for coupling load to an aircraft structure, the attachment part having a socket for retention of the bar-end, the socket providing a concave thrust surface. A contact mechanism is provided to monitor relative displacement of the convex thrust surface within the concave thrust surface in a direction along an axis of the attachment part. In this way, changes in backlash and loading of the secondary load path can be detected. The contact mechanism comprises a protuberance extending from the bar-end along the main rotational axis of the failsafe bar and a displaceable contact surface provided by a displaceable member in the attachment part, the relative position of which is monitored by a displacement sensor.

Abstract: A spar for an airfoil comprises a core, e.g. a foam core, a central structural member extending through the core, an outer structural layer surrounding the core and central structural member and a plurality of yarns extending through the central structural member.

Abstract: An actuator assembly may comprise a screw shaft having a shaft axis; a drive arrangement pivotally supported about the screw shaft axis for driving the screw shaft, e.g., about the shaft axis or along the shaft axis, and a rod mounted to the drive arrangement at a location off the shaft axis for providing a primary function of reacting torque about the shaft axis on the drive arrangement. The rod may comprise a rod axis and provide a load path along the rod axis for reacting torque. The rod may also comprise a device for which provides a secondary function for the actuator assembly based on the load experienced along the load path provided by the rod.

Abstract: A propeller blade assembly comprises a propeller blade having a blade root for attaching the propeller blade to a hub. The blade root has a radially outer surface. The assembly further comprises a collar mounted to the blade root. The collar comprises at least two collar segments assembled around the radially outer surface of the blade root. Each collar segment has a radially inner surface, an opposed radially outward surface and first and second circumferential end lugs. The lugs receive fasteners for coupling the collar segments together to form the collar. The collar segments are formed from a flexible plastics material and the radially inner surface of each collar segments engages the radially outer surface of the blade root only over a limited circumferential extent of the collar segment.

Abstract: A module for a braking system includes a movable housing configured to transfer a braking force from an input shaft to an output shaft, a first movable member slidably received within the housing and connected to the output shaft, a second movable member slidably received within the housing, a first resilient member biased between the first movable member and the second movable member, such that a force applied to the second movable member is applied to the first movable member via the first resilient member, and a second resilient member biased between the second movable member and the housing, such that a force applied to the housing is applied to the second movable member via the second resilient member. The first resilient member yields or compresses upon application of a first braking force to the input shaft, and the second resilient member yields or compresses after the first resilient member.

Abstract: A propeller blade comprises a fibre reinforced blade structure spar having a blade retention section formed at one end thereof, and at least one metallic formation spray deposited onto said blade retention section.

Abstract: A blade pitch adjustment system comprising a yoke arranged to be moved in a first direction in response to an actuator; a plurality of trunnion pins arranged to be attached to a respective propeller blade; a respective contact surface between the yoke and each trunnion pin such that movement of the yoke causes rotation of the blades, and wherein the contact surfaces differ so as to create different angles of rotation of the blades at different points of yoke movement or actuator stroke.