Aeronautics and astronautics – Aircraft structure – Passenger or crew accommodation
Reexamination Certificate
1997-02-19
2001-07-24
Jordan, Charles T. (Department: 3644)
Aeronautics and astronautics
Aircraft structure
Passenger or crew accommodation
Reexamination Certificate
active
06264141
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a frangible aircraft floor comprising a perforated thin film for aircraft decompression protection.
BACKGROUND ART
Wide-bodied commercial jet aircraft are potentially subject to critical damage to the passenger compartment floor as a result of a large hole made in a lower cargo compartment, such as a hole formed by the sudden opening of a cargo door or a small bomb explosion, while the airplane cabin and cargo compartments are at a high pressure differential with respect to the outside atmospheric air pressure. Upon rapid decompression of the lower cargo compartment, severe downloads may be placed on the passenger floor due to the air pressure above the floor. The air above the floor cannot escape rapidly into the cargo compartment and eventually to atmosphere, as the passenger compartment floor is normally made as a sealed floor due to air conditioning requirements, noise requirements, liquid spillage prevention requirements and appearance considerations. Consequently, because of this pressure differential, structural damage to the floor and nearby components, controls, and systems may occur, with the safety of the aircraft potentially placed in jeopardy.
A relatively new Federal Aviation Administration rule has required that airframe manufacturers either strengthen the floor structure to withstand the sudden differential pressure load, or increase the venting capacity between the upper and lower compartments in order to reduce the maximum differential pressure to a level which the existing floor could withstand.
Since strengthening of the floor structure would require significant weight increase, which would adversely affect aircraft performance, a decompression vent box was developed to increase the venting capacity between upper and lower compartments. This vent box is described below with reference to
FIGS. 1 and 2
.
The decompression vent box
10
, shown in
FIGS. 1 and 2
, is provided for allowing air flow through the floor support opening
12
in the event of decompression. The vent box
10
comprises a collapsible diaphragm
14
hinged between a baffle
16
and face panel
18
. A spring
20
holds the vent box
10
in the closed position, as shown in
FIG. 1
, until a negative pressure differential force acting against the hinged diaphragm
14
pivots the face panel
18
and collapses the hinged diaphragm
14
, as shown in
FIG. 2
, to allow air flow through the floor support opening
12
. Accordingly, in the event of a sudden opening of a large hole in the lower cargo compartment, the diaphragm will collapse and expose the floor support opening
12
, which is large enough to handle increased venting to reduce the differential pressure to a level which the existing floor could withstand. Also, in the case of sudden decompression in the upper compartment due to loss of cabin door or holes in the upper fuselage skin due to fan blade penetration as the result of an uncontained engine failure, the hinged flapper
17
in the face panel
18
swings open to allow increased airflow to increase venting and reduce the differential pressure to a level which the floor can withstand.
Under normal operation, small holes formed in the hinged flapper
17
act as a flow-controlling orifice to allow limited air movement therethrough.
Some problems with this vent box design are that it may add approximately 450 pounds of weight to the aircraft, its reliability has been questioned, and it has been known to leak uncontrollably.
Accordingly, it is desirable to provide a frangible aircraft floor with reduced weight and improved reliability.
DISCLOSURE OF INVENTION
The present invention overcomes the above-referenced shortcomings described with reference to the prior art by providing a frangible aircraft floor which includes a th in film positioned over a floor support opening, wherein the film is perforated in a manner to rupture when a predetermined pressure difference exists on opposing sides of the film, thereby allowing increased airflow through the opening for pressure equalization.
In one embodiment, the present invention provides a frangible aircraft floor including a floor support having at least one opening formed therethrough, and a frame secured over the opening. A thin film is positioned over the frame. The film comprises a plurality of apertures form e d therein to allow minimal airflow therethrough for normal ventilation. The thin film also has a perforation configured to rupture when a predetermined pressure difference exists on opposing sides of the film.
The present invention also provides a method of equalizing pressure in an airplane between a passenger compartment and a cargo compartment positioned below the passenger compartment and separated therefrom by a floor assembly. The method comprises positioning a thin frangible film having an aperture therein upon a floor support having an opening extending between the passenger and cargo compartments. The pressure is equalized between the passenger and cargo compartments during normal operating conditions by freely passing air through the aperture in the thin frangible film. The thin frangible film is automatically ruptured when a predetermined pressure difference exists between the passenger and cargo compartments in order to allow airflow through the floor support enabling rapid pressure equalization between the passenger and cargo compartments in the event of a sudden loss of pressure in one of the compartments, thereby limiting pressure load on the floor assembly.
The present invention provides a frangible aircraft floor comprising a thin perforated film positioned over a floor support opening, such that a predetermined pressure difference will tear the perforation to allow increased air flow through the opening. The frangible aircraft floor of the present invention reduces weight and improves reliability.
The above objects and other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings.
While embodiments of this invention a re illustrated and disclosed, these embodiments should not be construed to limit the claims. It is anticipated that various modifications and alternative designs may be made without departing from the scope of this invention.
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“McDonnell Douglas DC-10”, article, FLIGHT International, 7 pgs.
Shim Hyo S.
Wiles Steve A.
Brooks & Kushman P.C.
Dinh Tien
Jordan Charles T.
McDonnell Douglas Corporation
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