Abstract: A pitch control mechanism is provided for angular displacement of propellers of a propeller assembly of an engine arrangement. The pitch control mechanism has an epicyclic gear system rotating with the propeller assembly. The pitch control mechanism further has a drive gear controlling the rotational speed of the first epicyclic input in the rotating frame of reference of the propeller assembly, a control gear controlling the rotational speed of the second epicyclic input in the rotating frame of reference of the propeller assembly, and a drive mechanism rotating with the propeller assembly. The drive mechanism accepts rotary motion from the epicyclic output to deliver an output motion which angularly displaces the propellers of the propeller assembly.

Abstract: A back-up featherer is provided for an engine arrangement. The engine arrangement has a main hydraulic actuator which operates a pitch change mechanism to angularly displace propellers of a propeller assembly of the engine arrangement, the pitch change mechanism and main hydraulic actuator rotating with the propeller assembly. The back-up featherer has one or more brakes located on a static structure of the engine arrangement. The back-up featherer further has one or more input gears rotatable about respective axes, which axes rotate with the propeller assembly. The input gears are operatively connected to the brakes such that, when the brakes are activated, the input gears rotate about their axes.

Abstract: A pitch control mechanism for controlling the pitch of propeller assembly propellers has a hydraulic actuator, main hydraulic fluid supply lines, first back-up hydraulic fluid supply lines, and second back-up hydraulic fluid supply lines. The hydraulic actuator has first and second hydraulic cylinders that each angularly displace the propellers between fine and coarse positions. The main hydraulic fluid supply lines supply fluid to the first and second hydraulic cylinders for operating the hydraulic cylinders. The first back-up hydraulic fluid supply lines supply fluid to the hydraulic cylinder for displacing the propellers to a coarser position. The second back-up hydraulic fluid supply lines supply fluid to the second hydraulic cylinder for displacing the propellers to a coarser position. When the main hydraulic fluid supply lines supply inadequate fluid, the first and/or second back-up hydraulic fluid supply lines can supply fluid for displacing the propellers to a coarser position.

Abstract: A back-up featherer for an engine arrangement having a main hydraulic actuator which angularly displaces propellers of a propeller assembly of the engine arrangement, and fluid supply lines for transferring hydraulic fluid between a hydraulic pressure power source located on a static structure of the engine arrangement and the main hydraulic actuator. The back-up featherer has a back-up actuator assembly for angular displacement of the propellers, the back-up actuator assembly rotating with the propeller assembly, a signal detector operatively connected to the back-up actuator assembly and rotates with the propeller assembly, and a back-up rotating coupling. A static side of the back-up rotating coupling is mounted to the static structure of the engine arrangement and communicates with a regulator located on a static structure of the engine arrangement. A rotating side of the back-up hydraulic rotating coupling rotates with the propeller assembly and communicates with the signal detector.

Abstract: A pitch change apparatus is provided for a propeller assembly having a row of propeller blades which rotate around an axis of the assembly. The apparatus has a unison ring which is coaxial with the propeller assembly. The unison ring is movable to drive respective mechanisms for varying the pitch of the blades. The apparatus further has a plurality of pitch lock assemblies circumferentially distributed around the unison ring. Each pitch lock assembly has a free state which allows movement of the unison ring and a locked state which prevents or limits movement of the unison ring and thus prevents or limits variation of the pitch of the blades. The pitch lock assembly moves from the free to the locked state when the assembly receives a signal to lock the blades.

Abstract: A pitch change apparatus comprises a hydraulic actuator for angular displacement of propellers of the propeller assembly. The hydraulic actuator has a piston and cylinder arrangement which defines fine and coarse fluid chambers. Increasing the volume of the fine chamber at the expense of the coarse chamber results in angular displacement of the propellers to a finer pitch. Increasing the volume of the coarse chamber at the expense of the fine chamber results in angular displacement of the propellers to a coarser pitch. The pitch change apparatus further comprises one or more fine hydraulic lines carrying hydraulic fluid to and from the fine chamber, and a coarse hydraulic line carrying hydraulic fluid to and from the coarse chamber. The apparatus further comprises a pressure-sensing check valve which fluidly isolates the coarse chamber from the coarse hydraulic line if the pressure in the coarse hydraulic line falls below a threshold pressure.

Abstract: A back-up featherer is provided for an engine arrangement having a main hydraulic actuator which angularly displaces propellers of a propeller assembly of the engine arrangement. The back-up featherer has a back-up hydraulic actuator for angular displacement of the propellers, the back-up hydraulic actuator rotating with the propeller assembly. The back-up featherer further has one or more back-up fluid supply lines for transferring hydraulic fluid between a hydraulic pressure power source located on a static structure of the engine arrangement and the back-up hydraulic actuator. The back-up featherer further has a back-up hydraulic rotating coupling, the back-up fluid supply lines fluidly communicating with the back-up hydraulic actuator via the back-up rotating coupling. A static side of the back-up hydraulic rotating coupling is mounted to the static structure of the engine arrangement, and a rotating side of the back-up hydraulic rotating coupling rotates with the propeller assembly.

Abstract: An engine arrangement has a gear assembly that drives a first propeller assembly. The gear assembly is driven by a power drive shaft that joins to the gear assembly at a first side. The engine arrangement has a static conduit that extends along a longitudinal internal cavity of the power drive shaft. The conduit penetrates the gear assembly such that a portion of the conduit projects from an opposing second side of the gear assembly. The engine arrangement has one or more first fluid supply lines routed along the static conduit between a hydraulic pressure power source and the first hydraulic actuator. A first hydraulic rotating coupling is mounted to the projecting portion of the static conduit. The first fluid supply lines fluidly communicate with the first hydraulic actuator via the first rotating coupling.

Abstract: A rotary coupling having a first element and a coaxial second element, the first and second elements being rotatable relative to each other and defining an annular passage between radially facing walls thereof. The coupling has a sealing ring at an end of the annular passage, the sealing ring being mounted to the wall of the first element and rotating relative to the second element, and having an active configuration in which the sealing ring is urged against the wall of the second element to seal the end of the annular passage, and a return configuration in which the sealing ring does not seal the end of the annular passage. A control system is used to apply a variable load to the sealing ring, wherein the sealing ring moves between the active and return configurations in response to variation in the applied load.

Abstract: A fuel supply system has valve communicating fuel to fuel nozzles. A fuel manifold supplies fuel to the valve. The valves are controlled by rotary drives extending from an actuator. At least part of the drive lies within the fuel manifold which serves to keep the drive cool and reduce significantly the number of seals required.

Abstract: A method of operating a blade pitch change system of a gas turbine engine and its arrangement, the system comprising a blade, an actuator, a pressurised fluid system and a control system that regulates pressurised fluid to the actuator to control its position and thereby the blade's pitch; the blade pitch change system operates in a forward thrust mode and a reverse thrust mode, the control system comprises a main pitch control valve and a first reverse blade control valve through which the pressurised fluid passes. The method comprises the steps of a) continuously varying the main control valve to change the blade's pitch within the forward thrust mode at a first rotational rate, b) switching the first reverse blade control valve on to change the blades' pitch between the forward thrust mode and the reverse thrust mode at a second rotational rate that is greater than the first rotational rate.

Abstract: A engine such as a gas turbine engine has a bladed rotor 24 having variable pitch blades 8. In normal operation, the pitch angle of the blades 8 is controlled by a primary pitch control system. A back-up system is provided for controlling the blades 8, for example to displace them to a feathered condition, in the event of failure of the primary pitch control system. The back-up system comprises a pump 32 mounted on the rotor 24, and driven by relative rotation between the rotor 24 and a contra-rotating rotor 23. In response to a failure signal on a conduit 48, the pump delivers hydraulic fluid under pressure to a secondary actuator 30, which acts on the blade 8.

Abstract: A flight control surface actuation system is provided in which a plurality of actuators (6-13) are connected to one another in order to synchronize their operation. Each actuator has its own gearbox such that the torque transmitted in the synchronizing element is kept low.