1. Field of the Invention
The present invention relates to a door assembly for use on an aircraft.
2. Description of the Prior Art
In commercial aircraft which are utilized today each aircraft has a fuselage in which a number of access openings are provided. Each access opening is equipped with a door. The conventional aircraft doors which are utilized to close access openings in an aircraft are quite complex and costly. Each door requires a complex hinge system in which a door is opened by first unlocking the door then pushing the door outwardly from the plane of the protective skin of the aircraft fuselage. Once the door has been pushed out from the plane of the surrounding skin of the aircraft it is opened by being swung in an arc about its hinges. The procedure is reversed in order to close a conventional aircraft door.
Because a conventional aircraft door must be capable of both translational and rotational movement, the hinge mechanism by means of which the door is attached to the fuselage of the aircraft is quite complex. As a result of this complexity conventional aircraft doors are quite costly to manufacture. Furthermore, the intricacy and complexity of the hinge mechanism enhances the likelihood of a malfunction.
Another problem that exists with conventional aircraft door closure systems is excessive weight. Due to the complexity and the many necessary parts in a conventional aircraft door assembly, the weight of such an assembly is rather large. In the aircraft industry weight is an extremely important consideration, and all possible measures are taken to reduce the weight of each and every component on an aircraft. However, even though weight is such an important factor in aircraft construction, conventional aircraft doors are still inordinately heavy.
Still another disadvantage of conventional aircraft door assemblies is that due to the complex hinge mechanism that is required, the sizes of the conventional aircraft doors must be limited. This is because there is a great cantilevered load which acts upon the hinge mechanisms when the doors are opened. As a consequence, the sizes of the access openings into which conventional aircraft doors are mounted must be limited in order to avoid hinge mechanisms which have an even greater weight. The limited size of the access openings reduces the speed with which both cargo and passengers can be loaded onto and unloaded off of an aircraft. Furthermore, the limited size of access openings in a conventional aircraft restricts the rate at which passengers can exit an aircraft in an emergency. This creates an important concern for passenger safety. The restricted size of the openings thereby creates problems of convenience, safety and cost in loading and unloading an aircraft.