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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

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. The back-up featherer further has one or more load application members which rotate with the propeller assembly and which are operatively connected to the input gears such that, when the input gears rotate about their axes, the load application members bear against respective engagement portions of the pitch change mechanism. This applies a load to the pitch change mechanism which results in angular displacement of the propellers.

대표청구항 ▼

1. A back-up featherer for an engine arrangement having 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, w

1. A back-up featherer for an engine arrangement having 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, wherein the back-up featherer has: one or more brakes located on a static structure of the engine arrangement,one or more input gears rotatable about respective axes, which axes rotate with the propeller assembly, the input gears being operatively connected to the brakes such that, when the brakes are activated, the input gears rotate about their axes, andone or more load application members which rotate with the propeller assembly and which are operatively connected to the input gears such that, when the input gears rotate about their axes, the load application members bear against respective engagement portions of the pitch change mechanism to apply a load to the pitch change mechanism which results in angular displacement of the propellers. 2. A back-up featherer according to claim 1, wherein the, or each, load application member has a detent mechanism which detains the load application member, such that, when the brakes are de-activated, the load application members are prevented from bearing against the engagement portions. 3. A back-up featherer according to claim 1, wherein the connection between the brakes and the input gears comprises a ring gear which is coaxial with the propeller assembly and which drives the input gears, the brakes being connected to the ring gear such that, when the brakes are activated, the ring gear rotates relative to the propeller assembly to rotate the input gears about their axes. 4. A back-up featherer according to claim 1, wherein the connection between the brakes and the input gears comprises a ring gear which is coaxial with the propeller assembly and which drives the input gears, the brakes being connected to the ring gear such that, when the brakes are activated, the ring gear rotates relative to the propeller assembly to rotate the input gears about their axes. 5. A back-up featherer according to claim 3, wherein the connection between the, or each, brake and the ring gear comprises a respective brake gear which extends from the brake to engage the ring gear, the brake gear being rotatable about an axis which is fixed relative to the static structure of the engine arrangement such that, when the brakes are activated, resistance to rotation of the brake gears about their axes is increased, causing the ring gear to rotate relative to the propeller assembly. 6. A back-up featherer according to claim 4, wherein the connection between the, or each, brake and the ring gear comprises a respective brake gear which extends from the brake to engage the ring gear, the brake gear being rotatable about an axis which is fixed relative to the static structure of the engine arrangement such that, when the brakes are activated, resistance to rotation of the brake gears about their axes is increased, causing the ring gear to rotate relative to the propeller assembly. 7. A back-up featherer according to claim 1, wherein the connection between the input gears and the load application members comprises respective actuation screws which rotate with the propeller assembly and which, on activation of the brakes, accept rotational motion from the input gears, the rotational motion being converted into translational motion of the load application members, causing the load application members to bear against the engagement portions. 8. A back-up featherer according to claim 1, wherein the pitch change mechanism has a unison ring which is coaxial with the propeller assembly, the unison ring being movable by the main hydraulic actuator and by the brakes to operate drive systems for angular displacement of respective propellers. 9. An engine arrangement having: a first propeller assembly,a first pitch change mechanism which rotates with the first propeller assembly and which angularly displaces propellers of the first propeller assembly, anda first main hydraulic actuator which rotates with the first propeller assembly and which operates the first pitch change mechanism;wherein the engine arrangement further has a back-up featherer according to any one of the preceding claims for angular displacement of the propellers of the first propeller assembly. 10. An engine arrangement according to claim 9, further having a gear assembly that drives the first propeller assembly, the gear assembly being driven by a power drive shaft that joins to the gear assembly at a first side thereof; wherein the connection between the brakes and the input gears is on the first side of the gear assembly. 11. An engine arrangement according to claim 10, wherein the power drive shaft has a longitudinally extending internal cavity, and the engine arrangement further has: a static conduit which extends along the internal cavity, the conduit penetrating the gear assembly such that a portion of the conduit projects from an opposing second side of the gear assembly,one or more first fluid supply lines for transferring hydraulic fluid between a primary hydraulic pressure power source located on a static structure of the engine arrangement and the first main hydraulic actuator, the first fluid supply lines being routed inside the static conduit, anda first main hydraulic rotating coupling mounted to the projecting portion of the static conduit, the first fluid supply lines fluidly communicating with the first main hydraulic actuator via the first main hydraulic rotating coupling. 12. An engine arrangement according to claim 11 which is for a contra-rotating engine, the arrangement further having: a second propeller assembly arranged to rotate in an opposite direction to the first propeller assembly, the gear assembly also driving the second propeller assembly,a second pitch change mechanism which rotates with the second propeller assembly and which angularly displaces propellers of the second propeller assembly,a second main hydraulic actuator which rotates with the second propeller assembly and which operates the second pitch change mechanism,one or more second fluid supply lines for transferring hydraulic fluid between the primary hydraulic pressure power source and the second main hydraulic actuator, the second fluid supply lines being routed inside the static conduit, anda second main hydraulic rotating coupling which is mounted to the projecting portion of the static conduit, the second fluid supply lines fluidly communicating with the second main hydraulic actuator via the second main hydraulic rotating coupling.