Abstract: A strut for propping open the door of an aircraft including an outer tube connected at one end to the aircraft and a telescoping inner member connected to the aircraft door. The inner member is extended out of the outer tube when the door is fully opened and automatically locks in place. The strut can be unlocked by grasping a sleeve mounted on the outer tube, pulling it downwardly while rotating the same clockwise. The strut remains locked until the door is lifted upwardly until it stops thereby unlocking the strut. Lowering the door returns the strut to its stowed position with the inner member received within the outer tube.