Patent ID: 7448855

Claim:
A droop stop mechanism for a main rotor blade of a helicopter, comprising: a pair of opposing stops respectively disposed on a hub of the rotor and a pitch shaft of the blade; an elongated shaft rotatably mounted to the hub of the rotor and having a long axis disposed tangential to a direction of rotation thereof; a torsion spring disposed concentrically about the shaft and having a fixed first end and an opposite second end coupled to the shaft for torsional biasing of the shaft by the spring; an arm having a first end attached at a right angle to a first end of the shaft for conjoint rotation therewith and an opposite second end; an interposer mounted on the second end of the shaft for rotation in a plane perpendicular to a flap hinge of the blade; the torsion spring biasing the interposer to a first angular position disposed between the two stops such that downward deflection of the blade about the flap hinge is substantially limited, a spacer having opposite first and second ends, the first end being attached at a right angle to the shaft and the arm; and, a weight disposed at the second end of the spacer such that a radially outward centrifugal force acting thereon with rotation of the rotor causes the shaft and arm to rotate conjointly so as to overcome the bias of the torsion spring on the shaft and urge the interposer from the first angular position to a second angular position at which a greater downward deflection of the blade about the flap hinge is allowed.