Patent ID: 7575193

Claim:
An on-board anti-crash method for an undercarriage ( 2 ) of an aircraft ( 1 ), said undercarriage ( 2 ) being of the retractable type, and comprises: a landing gear leg ( 9 ) hinged to a force take-up structure of the aircraft ( 1 ) about a transverse pivot axis ( 8 ) in order to enable it to be extended and retracted; a retraction actuator ( 6 ) having a coupling end hinged to the take-up structure in order to cause the landing gear leg ( 9 ) to be extended and retracted; first anti-crash means for acting during a first stage of a crash to damp shortening of the undercarriage ( 2 ); and second anti-crash means ( 16 ) for acting during a second stage of a crash to inhibit retraction and to brake pivoting of the leg ( 9 ); wherein, during a second stage of a crash, after the end of the first stage, the method comprises: functionally separating the landing gear leg ( 9 ) relative to the retraction actuator ( 6 ); retaining and blocking the retraction actuator ( 6 ); and once the actuator ( 6 ) has been blocked, providing controlled braking of the pivoting of the landing gear leg ( 9 ) about its transverse pivot axis ( 8 ), wherein the step of braking pivoting is performed at least in part by a stage of irreversibly lengthening of a deformable connection ( 14 , 19 , 25 ) between the take-up structure ( 5 ) and the landing gear leg ( 9 ) at a constant force, the lengthening stage is performed at least in part by a stage of extending by partial destruction a nonpermanent connection ( 14 , 25 , 27 ) between the take-up structure ( 5 ) and the leg ( 9 ), wherein said connection ( 14 ) being obtained by causing a member ( 25 , 31 ) of said connection ( 14 ) to become engaged prior to the second stage of a crash, and said connection ( 14 ) is caused to become engaged prior to the second stage of a crash by a sliding tube ( 12 ) of the landing gear leg ( 9 ) being caused to engage with a collar ( 31 ) or the like.