Abstract: A thrust reverser actuator lock mechanism comprising a rotatable shaft, rotation of which in one direction from a rest position drives an associated thrust reverser from a stowed position towards an operative position in use, retractable abutment means having a rest position abutting an element rotatable with the shaft to prevent rotation of the shaft, resilient means urging said abutment means to said rest position, and, mechanical latch means sensitive to the speed of rotation of said shaft for latching said abutment means in a retracted position against the action of said resilient means when the rotational speed of said shaft exceeds a predetermined value.