Gas turbine engine

An engine arrangement has a first propeller assembly (21a), and a first hydraulic actuator (23a) for angular displacement of propellers (22a) of the first propeller assembly, the first hydraulic actuator rotating with the first propeller assembly. The engine arrangement further has a gear assembly that drives the first propeller assembly. The gear assembly is driven by a power drive shaft (17) that joins to the gear assembly at a first side thereof. The power drive shaft has a longitudinally extending internal cavity. The engine arrangement further has a static conduit (26) which extends along the internal cavity of the power drive shaft. The conduit penetrates the gear assembly such that a portion (26b) of the conduit projects from an opposing second side of the gear assembly. The engine arrangement further has one or more first fluid supply lines (28a) for transferring hydraulic fluid between a hydraulic pressure power source (27) located on a static structure of the engine arrangement and the first hydraulic actuator. The first fluid supply lines are routed along the static conduit. A first hydraulic rotating coupling (30a) 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.