Over-centering blade lock

A blade lock for a tiltrotor aircraft to enable and disable a folding degree of freedom and a pitching degree of freedom of a rotor blade assembly, the blade lock comprising:

• a crank and a blade link coupled at a crank pivot point, the blade link rotatably coupled to a rotor blade and the crank rotatably coupled to a cuff of the rotor blade assembly and operable to rotate relative to the cuff;
• a lever pivotally connected to the cuff at a lever pivot point and having a fold locked position securing a crank pivot joint to the cuff disabling the folding degree of freedom and a fold unlocked position enabling the folding degree of freedom;
• a bellcrank pivotally connected to the cuff at a bellcrank pivot point;
• a center position extending through the bellcrank pivot point and the crank pivot point;
• a fold link having an end pivotally connected to the lever at a link-lever connection and an opposite end pivotally connected to the bellcrank at a link-bellcrank connection;
• and
• a projection extending from the bellcrank at a location between the bellcrank pivot point and the link-bellcrank connection;
• wherein the lever is unsecured in the fold locked position when the fold link is in the center position and the projection is not in direct contact with the cuff;
• wherein the lever is secured in the fold locked position when the fold link is in an over-center position and the projection is in direct contact with the cuff;
• and
• wherein the fold link is deflected or compressed in the center position when the fold link is rotated between the fold unlocked position and the over-center position.