An apparatus for opening and closing an aircraft landing gear bay door comprising: mechanical coupling means configured to couple the landing gear and the landing gear bay door, the mechanical coupling means comprising: a drive rod configured to be pivotably connected to the landing gear; a door rod (26, 126) configured to be coupled to the landing gear bay door; an input crank (16, 116) pivotably connected, at a first end, to the drive rod and configured to be coupled to the landing bay about an input crank pivot point; an output crank (24, 124) pivotably connected to the door rod (26, 126) and configured to be coupled to the landing bay about an output crank pivot point; at least one of the input (16, 116) and the output (24, 124) crank having at least one projection (20, 120) located thereon, the other of the input (16, 116) and ouput (24, 124) crank having an aperture (22, 122) configured to receive the projection (20, 120) within, the at least one projection (20, 120) and aperture (22, 122) configured to connect the input (16, 116) and ouput (24, 124) cranks so that the projection (20, 120) is configured to move within the aperture (22, 122) upon pivotal movement of the input crank (16, 116) to cause the output crank (24, 124) to rotate to open and close the landing gear bay door, and wherein initial extension of the landing gear initiates movement of the landing gear bay door to an open position, extension of the landing gear past the landing gear bay door maintains the landing gear bay door in the open position to allow the landing gear to pass, and approaching full extension of the landing gear initiates movement of the landing gear bay door to a closed position. mechanical coupling means configured to couple the landing gear and the landing gear bay door, the mechanical coupling means comprising: a drive rod configured to be pivotably connected to the landing gear; a door rod (26, 126) configured to be coupled to the landing gear bay door; an input crank (16, 116) pivotably connected, at a first end, to the drive rod and configured to be coupled to the landing bay about an input crank pivot point; an output crank (24, 124) pivotably connected to the door rod (26, 126) and configured to be coupled to the landing bay about an output crank pivot point; at least one of the input (16, 116) and the output (24, 124) crank having at least one projection (20, 120) located thereon, the other of the input (16, 116) and ouput (24, 124) crank having an aperture (22, 122) configured to receive the projection (20, 120) within, the at least one projection (20, 120) and aperture (22, 122) configured to connect the input (16, 116) and ouput (24, 124) cranks so that the projection (20, 120) is configured to move within the aperture (22, 122) upon pivotal movement of the input crank (16, 116) to cause the output crank (24, 124) to rotate to open and close the landing gear bay door, and wherein initial extension of the landing gear initiates movement of the landing gear bay door to an open position, extension of the landing gear past the landing gear bay door maintains the landing gear bay door in the open position to allow the landing gear to pass, and approaching full extension of the landing gear initiates movement of the landing gear bay door to a closed position. a drive rod configured to be pivotably connected to the landing gear; a door rod (26, 126) configured to be coupled to the landing gear bay door; an input crank (16, 116) pivotably connected, at a first end, to the drive rod and configured to be coupled to the landing bay about an input crank pivot point; an output crank (24, 124) pivotably connected to the door rod (26, 126) and configured to be coupled to the landing bay about an output crank pivot point; at least one of the input (16, 116) and the output (24, 124) crank having at least one projection (20, 120) located thereon, the other of the input (16, 116) and ouput (24, 124) crank having an aperture (22, 122) configured to receive the projection (20, 120) within, the at least one projection (20, 120) and aperture (22, 122) configured to connect the input (16, 116) and ouput (24, 124) cranks so that the projection (20, 120) is configured to move within the aperture (22, 122) upon pivotal movement of the input crank (16, 116) to cause the output crank (24, 124) to rotate to open and close the landing gear bay door, and wherein initial extension of the landing gear initiates movement of the landing gear bay door to an open position, extension of the landing gear past the landing gear bay door maintains the landing gear bay door in the open position to allow the landing gear to pass, and approaching full extension of the landing gear initiates movement of the landing gear bay door to a closed position.