HYDRAULIC CIRCUIT FOR ADJUSTING THE TURBINE PITCH

Abstract

An actuation system (1) for adjusting the pitch of aircraft engine fan blades (200) comprising a hydraulic cylinder (5), including an isolation valve (71) adapted to selectively adopt a first and a second configuration, such that: - when the isolation valve (71) is in the first configuration, the hydraulic cylinder (5) is configured to be position-controlled by a control fluid from a main hydraulic circuit (4a); and - when the isolation valve (71) is in the second configuration, the piston of the hydraulic cylinder (5) can move in a first direction of travel by the action of a control fluid from an auxiliary hydraulic circuit (4b), the fan blade orienting itself towards a large pitch position, and the auxiliary hydraulic circuit (4b) not being hydraulically connected with the main hydraulic circuit (4a). Figure for the abstract: Fig. 5