AMORTISSEUR DE DESCENTE DE TRAIN D'ATTERRISSAGE D'AVION

The invention relates to a shock absorber comprising a main body and a rod-piston, with the rod-piston being retracted when the landing gear is down and extended when the landing gear is up. The main body comprises, in succession, three chambers that are separated by associated partitions, and that comprise: a first hydraulic chamber in which the rod-piston slides freely; a chamber in which a separator piston slides, delimiting a second hydraulic chamber; and a chamber in which another piston slides, delimiting both a third hydraulic chamber and a chamber containing gas under high pressure. Communication means are provided between said chambers together with two associated electrically controlled valves enabling corresponding fluid connections to be selectively established. Thus, in a normal regime, the shock absorber enables a certain amount of energy to be stored while the landing gear is being lowered, which energy is restored next time the landing gear is raised; while during an emergency regime, the shock absorber participates in braking the landing gear while it is being lowered in an emergency, e.g. under its own weight after a jammed lowering actuator has been declutched.