Propeller assembly pitch change apparatus

摘要

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 comprises 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 comprises 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.