Passenger Door Lock for Drop-Down Style Doors on an Aircraft

Apparatus, systems, and methods for selectively locking and unlocking a passenger door. The apparatus includes a first shaft, having a first longitudinal centerline, and a member, connected to the first shaft. A handle is connected to the first shaft via the member, the handle being movable via rotation of the first shaft from a locked position and an unlocked position. A first protrusion extends from the handle and a latch crank is connected to the second shaft. A second protrusion extends from the latch crank and a linkage is connected between the latch crank and the member. When the handle in the locked position, the first protrusion is positioned adjacent to the second protrusion to prevent rotation of the second shaft. When the handle is in the unlocked position, the first protrusion is positioned away from the second protrusion to enable the second shaft to rotate.