Step operated locking mechanism for aircraft lower door

In an aircraft including a fuselage, a generally rectangular doorframe along one side of the fuselage and defining a vertical axis doorway, a generally rectangular upper door, hinge mounted along its upper, horizontal edge to the top of said doorframe for pivoting about a horizontal axis, a generally rectangular lower door, hinge mounted about its lower horizontal edge to the bottom of said doorframe, said upper and lower doors forming a sectional clamshell type door assembly for said aircraft, at least one latch pin mounted along a side edge of the lower door for lateral projecting movement into a suitable opening within said doorframe for locking the lower door in closed position, the improvement comprising:

• a step pivotably mounted on the interior of the lower door for pivoting between a first position with the step generally flush with the inner surface of the inner door and a second position projecting generally horizontally outwardly thereof, and
• a linkage system operatively connecting said step to said at least one latch pin and responsive to pivoting of said step for shifting the latching pin from latch projected position when the step is in its first position, to pin retracted, door release position when said step is pivoted to said second, projected position.