Aeronautics and astronautics – Aircraft structure – Details
Reexamination Certificate
1998-04-03
2001-02-20
Poon, Peter M. (Department: 3644)
Aeronautics and astronautics
Aircraft structure
Details
Reexamination Certificate
active
06189832
ABSTRACT:
The present invention relates generally to the field of latch mechanisms and, more particularly, to a permanently connected remote latch mechanism which secures a cowling to an aircraft structure. Although the present invention is subject to a wide range of applications, it is especially suited for use with aircraft, and will be particularly described in that connection.
BACKGROUND OF THE INVENTION
Modern jet engines are mounted on an aircraft by pylons or a similar support structure. A nacelle which circumscribes the engine forms an enclosed shelter for the engine. The nacelle is generally supported in part from the engine and in part from the engine pylon. The nacelle is aerodynamically contoured to reduce aerodynamic drag on the nacelle during operation of the aircraft.
The nacelle includes a pair of thrust reverser cowlings which form a large conical shaped structure that wraps around the aircraft engine. During aircraft operation these thrust reverser cowlings define an outer wall of the engine exhaust nozzle. Thrust reverser cowlings must be capable of withstanding considerable hoop loads caused by the high pressure of the jet exhaust stream flowing therein. The thrust reverser cowlings are normally hingedly connected to the upper portion of the nacelle near the point where the nacelle is attached to the engine pylon. The thrust reverser cowlings are hinged, so that they can be pivoted upwards, to provide access to the engine for maintenance and repair. During aircraft operation the thrust reverser cowlings must be pivoted downward into closed positions in which their ends, at the bottom split line, are adjacent to one another or adjacent to an interposed strut.
The thrust reverser cowlings are held together by tension latches during operation. The ends of the thrust reverser cowlings are normally attached together by bottom mounted tension latches located at the bottom split line. The thrust reverser cowlings are also attached at the top of each thrust reverser cowling, near the hinge line, to the aircraft structure by tension latches.
When closing the thrust reverser cowlings, the bottom tension latches are easily closed because they are clearly visible to a mechanic from the ground and can be properly closed directly by hand. The top mounted tension latches, however, are not visible to mechanics on the ground and are almost completely inaccessible. Several types of latch mechanisms attempt to solve the problem of the inaccessibility of the top mounted tension latches by utilizing remotely actuated latch mechanisms which use a hook or opposing jaws, as latches, to engage a keeper. The hook or opposing jaws are actuated by the use of a cable allowing a mechanic to open and close the top mounted tension latch from the ground at the bottom of the thrust reverser cowling. When the top mounted tension latch is remotely opened the hook or opposing jaws disengage from the keeper allowing the thrust reverser cowling to be opened. After closing the thrust reverser cowling, the top mounted tension latch can be remotely closed by the operation of the remotely actuated latch mechanism. A disadvantage of these remotely actuated latch mechanisms is that if the hook, opposing jaws, or keeper are not in the proper position, or are broken, it may be possible to close the latch without engaging the keeper thus giving a false indication that the latch is closed and resulting in a potentially unsafe condition. A further disadvantage of the use of these remotely actuated latch mechanisms is that there is no way for the mechanic to visually verify whether or not the hook or opposing jaws have properly engaged the keeper from the ground. Therefore, the mechanic operating the remotely actuated latch mechanism can never be sure that the latch is properly closed. Other types of complex mechanical linkages and even electrical actuators have been used to permit latches to be opened or closed from the ground with the same aforementioned disadvantages.
Various devices, in conjunction with the previously described remotely actuated latch mechanisms, have been used, unsuccessfully, to verify that the top mounted tension latch is properly closed. For example, previous attempts have been made to attach special devices such as sensors, feelers, or additional mechanisms to these top mounted tension latches to alert the mechanic if the latch is not properly engaged to the keeper. The disadvantage of using these devices is that these devices are also subject to failure, damage, or human error in utilizing them.
In view of the above, it should be appreciated that there is a need for a permanently connected remote latch mechanism that provides the advantages of having a top mounted tension latch that is permanently connected to a keeper on the aircraft structure insuring that when the latch is remotely closed that the keeper is always properly engaged, and therefore also obviating the need for special devices to verify that the latch is properly closed. The present invention satisfies these and other needs and provides further related advantages.
SUMMARY OF THE INVENTION
The present invention is embodied in a permanently connected remote latch mechanism having a top mounted tension latch that is permanently connected to a keeper on an aircraft structure insuring that when the latch is remotely opened and closed that the keeper is always properly engaged, and eliminates the need for special devices to verify that the latch is properly closed. Furthermore, the permanently connected remote latch mechanism, in combination with other features described below, possesses a unique relationship of slots and links that enables the motion of the latch mechanism such that the latch always properly opens without disengagement of the latch from the keeper and then allows the thrust reverser cowling to be pivoted to an open position also without disengagement of the latch from the keeper. The unique relationship of slots and links are also properly balanced to prevent the permanently connected remote latch mechanism from becoming bound in opening and closing.
The remotely actuated latch mechanism of the present invention is used for releasably securing a cowling to an aircraft structure. The latch mechanism includes a handle having an open and a closed position which is connected to a remote latch. The remote latch consists of a housing, a linkage mounted to the housing, and a strut connected to the linkage at a first end and to a keeper at a second end. The handle is connected to the linkage of the remote latch by a push/pull cable. The actuation of the handle from the closed position to the open position causes the push/pull cable to move the linkage of the remote latch such that the strut moves from a closed to an open position relative to the keeper. The movement of the strut to the open position allows the cowling of the aircraft to be opened.
An important feature of the present invention is that the strut and the keeper are securely engaged in the open and closed positions. An advantage of having a strut that is permanently connected to the keeper is that it insures that when the latch is remotely opened and closed that the keeper is always properly engaged and that the latch always properly closes. This is very important because the remote latch is mounted at the top of the thrust reverser cowling, near the hinge line, very high above the ground and a mechanic operating the remotely actuated latch mechanism cannot visually verify whether or not the latch has properly closed. If the latch does not properly close, as sometimes occurs in prior art devices where the latch can close without properly engaging the keeper, a potentially unsafe flight condition could occur. Advantageously, the latch of the present invention is permanently connected to the keeper insuring that when the latch is remotely closed that the keeper will be properly engaged, the latch will properly close, and a potentially unsafe flight condition will not occur due to the latch not properly engaging the keeper.
A further advantage of the present in
Hartwell Corporation
Nelson Jagnola A.
Poon Peter M.
Pretty, Schroeder & Poplawski
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