BACKGROUND

[01] Field of the Invention

[02] The present invention generally relates to airflow metering devices and more particularly relates to the metering of airflow in an aircraft passenger cabin.

[03] Related Art

[04] Aircraft passenger cabin exhaust airflow must be carefully controlled so that the passenger cabin maintains a positive pressure gradient relative to non- passenger compartments in the aircraft (usually found in the lower sections) in order to protect the occupied areas from potential ingress of toxic smoke, fumes, vapors and/or fire extinguishing agent under certain failure or emergency conditions. In commercial aircraft, passenger cabin exhaust airflow is typically controlled by features that are incorporated into the cabin interior sidewall panels. Private executive transport aircraft typically utilize customized cabinetry at the sidewall. Although it is aesthetically pleasing to conceal the passenger cabin exhaust airflow features, it is costly to incorporate the passenger cabin exhaust airflow features into custom furnishings. Therefore, what is needed is an aircraft passenger cabin airflow metering apparatus and an aircraft passenger cabin airflow metering system that overcomes the significant problems described above.

SUMMARY

[05] To solve the above described problems, described herein is an airflow metering apparatus comprising one or more blowout discs supported in a frame to control the flow of aircraft passenger cabin exhaust air flow. The airflow metering apparatus may be installed completely independent of the passenger cabin interior furnishings. In order to satisfy rapid decompression relief venting requirements, the blowout disc supports are designed to allow a blowout disc to separate from the frames at a predetermined air pressure differential between opposite sides of the blowout disc, which significantly increases the air flow area. The blowout discs may be provided either with or without cutouts to allow localized airflow control during normal operation. The airflow metering apparatus is installed into existing weight reducing through holes in crease beam structures that are positioned between the frames of the aircraft at the main cabin floor level. Alternatively, the airflow metering apparatus is installed into existing truss structure frame bays that are positioned between the frames of the aircraft at the main cabin floor level. This design advantageously allows a combination of airflow metering apparatuses to be placed within the various discrete rooms of an aircraft passenger cabin to achieve the desired amount of airflow during normal operation and also achieve the desired amount of airflow during an abnormal rapid decompression scenario when the air pressure difference on opposite sides of the airflow metering apparatus blowout disc exceeds a predetermined threshold.

[06] Other features and advantages of the present invention will become more readily apparent to those of ordinary skill in the art after reviewing the following detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[07] The structure and operation of the present invention will be understood from a review of the following detailed description and the accompanying drawings in which like reference numerals refer to like parts and in which:

[08] FIG. 1A is a plan view diagram illustrating an example aircraft and passenger cabin according to an embodiment of the invention;

[09] FIG. 1 B is a side view diagram illustrating an example aircraft with a passenger cabin and non-passenger cabin according to an embodiment of the invention;

[10] FIG. 1 C is a cross-sectional view diagram illustrating an example aircraft having a passenger cabin space and a non-passenger cabin space according to an embodiment of the invention;

[11] FIG. 2A is an end view diagram illustrating an example aircraft passenger cabin defined by an aircraft frame structure having a plurality of frames and a plurality of floor beams according to an embodiment of the invention;

[12] FIG. 2B is an end view diagram illustrating an example aircraft passenger cabin defined by an aircraft frame structure having a plurality of frames and a floor that combine to define a plurality of frame bays according to an embodiment of the invention;

[13] FIG. 3 is a perspective view diagram illustrating an example aircraft passenger cabin defined by an aircraft frame structure having a plurality of frames and a plurality of floor beams defining a plurality of frame bays according to an embodiment of the invention;

[14] FIG. 4 is a plan view diagram illustrating an example truss structure frame bay and example crease beam webs positioned between frames according to an embodiment of the invention;

[15] FIG. 5 is a sectional view diagram of an example aircraft passenger cabin illustrating an example pair of frames separated by a partially closed crease beam web according to an embodiment of the invention;

[16] FIG. 6 is an expanded view diagram illustrating an example web metering device assembly according to an embodiment of the invention;

[17] FIGS. 7A, 7B, and 7C are plan view diagrams illustrating example blowout discs according to embodiments of the invention;

[18] FIG. 8A is an expanded view diagram illustrating an example web metering device assembly according to an embodiment of the invention;

[19] FIG. 8B is a perspective view diagram illustrating an example web metering device assembly according to an embodiment of the invention;

[20] FIG. 8C is a perspective view diagram illustrating an alternative example web metering device assembly according to an embodiment of the invention;

[21] FIG. 9 is a sectional view diagram of an example aircraft passenger cabin illustrating an example pair of frames separated by a partially closed crease beam web with expanded views of example web metering device assemblies prior to installation according to an embodiment of the invention;

[22] FIG. 10A is a sectional view diagram of an example aircraft passenger cabin illustrating a plurality of example web metering device assemblies installed over weight reducing holes in a crease beam web according to an embodiment of the invention;

[23] FIG. 10B is a sectional view diagram of an example aircraft passenger cabin illustrating a plurality of example web metering device assemblies installed over weight reducing holes in a crease beam web according to an embodiment of the invention;

[24] FIG. 1 1 is a sectional view diagram of an example aircraft passenger cabin illustrating an example truss structure frame bay and example truss metering device assemblies according to an embodiment of the invention; [25] FIG. 12 is an expanded view diagram illustrating an example truss metering device assembly according to an embodiment of the invention;

[26] FIG. 13 is a sectional view diagram of an example aircraft passenger cabin illustrating an example truss structure frame bay with expanded views of example truss metering device assemblies prior to installation according to an embodiment of the invention;

[27] FIG. 14A is a sectional view diagram of an example aircraft passenger cabin illustrating a plurality of example truss metering device assemblies installed over truss structure frame bays according to an embodiment of the invention;

[28] FIG. 14B is a sectional view diagram of an example aircraft passenger cabin illustrating a plurality of example truss metering device assemblies installed over truss structure frame bays according to an embodiment of the invention;

[29] FIGS. 15A, 15B, 15C and 15D are plan view diagrams illustrating example metering plate configurations according to embodiments of the invention;

[30] FIGS. 16A, 16B, 16C, 16D, 16E, 16F, 16G and 16H are plan view diagrams illustrating example metering plate assemblies for use in a truss metering device assembly according to embodiments of the invention;

[31] FIG. 17 is a plan view diagram illustrating an example private executive aircraft passenger cabin with a system for aircraft passenger cabin airflow metering according to an embodiment of the invention.

DETAILED DESCRIPTION

[32] Certain embodiments disclosed herein provide for an aircraft passenger cabin airflow metering apparatus and a system for using the aircraft passenger cabin airflow metering apparatus to manage air pressure and air flow within the passenger cabin of an aircraft such as a private executive aircraft. After reading this description it will become apparent to one skilled in the art how to implement the invention in various alternative embodiments and alternative applications. However, although various embodiments of the present invention will be described herein, it is understood that these embodiments are presented by way of example only, and not limitation. As such, this detailed description of various alternative embodiments should not be construed to limit the scope or breadth of the present invention as set forth in the appended claims. [33] FIG. 1A is a plan view diagram illustrating an example aircraft 10 and passenger cabin 20 according to an embodiment of the invention. In the illustrated embodiment, the passenger cabin 20 comprises a large portion of the interior space of the aircraft 10. In alternative embodiments, the passenger cabin 20 may include one or more discrete spaces (not shown) that may be separated from each other by way of walls or other structures that completely or substantially prevent airflow communication between the discrete spaces.

[34] FIG. 1 B is a side view diagram illustrating an example aircraft 10 with a passenger cabin 20 and non-passenger cabin 30 according to an embodiment of the invention. In the illustrated embodiment, the non-passenger cabin 30 may include discrete spaces (not shown) for luggage and other freight or equipment. Importantly, the passenger cabin 20 is separated from the non-passenger cabin 30 by way of at least a floor 40 that completely or substantially prevents airflow communication between the one or more spaces within the passenger cabin 20 and the one or more spaces within the non-passenger cabin 30.

[35] FIG. 1 C is a cross-sectional view diagram illustrating an example aircraft 10 having a passenger cabin 20 space and a non-passenger cabin 30 space according to an embodiment of the invention. In the illustrated embodiment, the passenger cabin 20 is separated from the non-passenger cabin 30 by way of at least a floor 40 that completely or substantially prevents airflow communication between the one or more spaces within the passenger cabin 20 and the one or more spaces within the non-passenger cabin 30.

[36] FIG. 2A is an end view diagram illustrating an example aircraft passenger cabin 20 defined by an aircraft frame structure having a plurality of frames 50 and a plurality of floor beams 60 according to an embodiment of the invention. In the illustrated embodiment, each of the plurality of frames 50 extends around the perimeter of the passenger cabin 20 and around and below the plurality of floor beams 60 that extend from each frame 50 on a first side of the passenger cabin 20 to the corresponding frame 50 on the opposite side of the passenger cabin 20. The frames 50 define at least a portion of the shape of the passenger cabin 20 and also provide a surface upon which to mount the exterior skin of the aircraft (not shown). One or more windows 70 may be installed between adjacent frames 50. In one embodiment, the distance between adjacent frames 50 is about 20 - 22 inches. [37] FIG. 2B is an end view diagram illustrating an example aircraft passenger cabin 20 defined by an aircraft frame structure having a plurality of frames 50 and a floor 40 that combine to define a plurality of frame bays 80 according to an embodiment of the invention. In the illustrated embodiment, the floor 40 is secured to the floor beams 60 and extends from the frames 50 on a first side of the passenger cabin 20 to the corresponding frames 50 on the opposite side of the passenger cabin 20. The floor 40 separates the passenger cabin 20 from the non- passenger cabin 30.

[38] Along each side perimeter of the floor 40, each pair of adjacent frames 50 define a frame bay 80 that lies between the exterior skin of the aircraft (not shown) and the floor 40. Although only a single frame bay is identified in the figure, there are a plurality of frame bays 80 in an aircraft. Each frame bay 80 may be filled with a crease beam web or a truss structure. The crease beam web may fully close the frame bay 80 or it may include one or more weight reducing through holes that leave the crease beam web partially open. Frame bays 80 having a truss structure or a crease beam web with weight reducing through holes allow air to freely flow between the passenger cabin 20 and the non-passenger cabin 30.

[39] FIG. 3 is a perspective view diagram illustrating an example aircraft passenger cabin 20 defined by an aircraft frame structure having a plurality of frames 50 and a plurality of floor beams 60 supporting a floor 40 and defining a plurality of frame bays 80 according to an embodiment of the invention. In the illustrated embodiment, each pair of frames 50 define a frame bay 80 that is positioned between the skin (not shown) of the aircraft and the floor 40. Typically, the frame bays 80 closer to the front of the aircraft are populated with truss structures while the frame bays 80 closer to the rear of the aircraft are populated with crease beam webs having weight reducing holes.

[40] FIG. 4 is a plan view diagram illustrating an example truss structure frame bay 1 10 and example crease beam webs 120, 150 positioned between frames 50A, 50B, 50C and 50D, respectively, according to an embodiment of the invention. In the illustrated embodiment, truss structure frame bay 1 10 is generally rectangular in shape and is defined by the exterior skin 100 of the aircraft on a first side and the perimeter edge of the aircraft floor 40 on a second side and frame 50A on a first end and frame 50B on a second end. Airflow through the truss structure frame bay 1 10 is partially blocked by truss structures 90. [41] Similarly, partially closed (also referred to as partially open) crease beam web 120 occupies an adjacent frame bay and is also generally rectangular in shape. Crease beam web 120 is positioned between the skin 70 and the floor 40 and frames 50B and 50C. Partially closed crease beam web 120 is a solid structure that includes weight reducing through holes 130A and 130B. Each through hole has an interior surface 140A and 140B, respectively. In the illustrated embodiment, weight reducing holes 140A and 140B are circular in shape, but alternative shapes may also be employed.

[42] Similarly, fully closed crease beam web 150 occupies an adjacent frame bay and is also generally rectangular in shape. Fully closed crease beam web 150 is positioned between the skin 70 and the floor 40 and frames 50C and 50D.

[43] FIG. 5 is a sectional view diagram of an example aircraft passenger cabin illustrating an example pair of frames 50 separated by a partially closed crease beam web 120 according to an embodiment of the invention. In the illustrated embodiment, the partially closed crease beam web 120 includes three weight reducing through holes 130 between the frames 50. On each of the opposite sides of the frames 50 a web metering device assembly 160 is positioned over the top of a similar weight reducing through hole (not shown). In the illustrated embodiment, the web metering device assembly 160 is circular in shape, however alternative shapes may also be employed.

[44] FIG. 6 is an expanded view diagram illustrating an example web metering device assembly 160 according to an embodiment of the invention. In the illustrated embodiment, the web metering device assembly 160 comprises a retaining ring 170 that may be implemented as a single piece or as two or more pieces. Retaining ring 170 is shown in the illustrated embodiment as having two pieces 170A and 17B. The retaining ring 170 includes a recess 175 along the interior portion of its bottom face. The recess 175 is configured to receive and position the blowout disc 180 between the retaining ring 170 and the base ring 210. The blowout disc may have one or more cutouts 190 or it may be solid. The blowout disc 180 may also include a lanyard 200 configured to prevent the blowout disc 180 from movement within the passenger cabin or non-passenger cabin in the event the blowout disc 180 releases. The retaining ring 170 positions the blowout disc 180 between the retaining ring 170 and the base ring 210 using fasteners such as screw 220 that may be employed, for example with one or more washers 230. The base ring 210 may also be implemented as a unitary piece as shown or as a combination of two or more segments that make up the base ring 210.

[45] In one embodiment, the retaining ring 170 and base ring 210 of the web metering device assembly 160 are made from a polyetherimide ("PEI") plastic. For example, the retaining ring 190 and base ring 210 may be made from an ULTEM™ PEI cylinder. In one embodiment, the blowout disc 180 comprises an ISODAMP polymer sheet. As previously discussed, the surface of the blowout disc 180 may be solid or may feature one or more cutouts 190. The one or more cutouts 190 may vary in size and shape and may be positioned anywhere on the blowout disc. The thickness of the blowout disc 180 may also vary. In all cases, the blowout disc 190 is designed to release from the web metering device assembly 160 at a predetermined differential pressure value. The shape of the web metering device assembly 160 is such that the shape of the blowout disc 190 is sized to match the shape of the previously described weight reducing through hole 130 in the crease beam web 120 to which the web metering device assembly 160 is affixed. In alternative embodiments the shapes may be circular or rectangular or polygonal. In one embodiment, the web metering device assembly 160 is affixed to the crease beam web 120 by adhesive bonding. For example, the base ring 210 is glued to the crease beam web 120. In alternative embodiments, different means for affixing the web metering device assembly 160 the crease beam web 120 can be employed, as will be understood by those skilled in the art.

[46] The overall shape of the web metering device assembly 160 may be cylindrical or may be any other shape that facilitates registration of each blowout disc 180 to its corresponding weight reducing through hole 130.

[47] FIGS. 7A, 7B, and 7C are plan view diagrams illustrating example blowout discs 180 according to embodiments of the invention. In the embodiment illustrated in FIG. 7A, the blowout disc 180 is solid and therefore configured to completely block the flow of air. In the embodiments of FIGS. 7B and 7C, the blowout discs 180 are configured to partially block the flow of air using different sized cutouts 190. The cutouts 190 are configured to allow the flow of a controlled amount of air. In one embodiment, each crease beam web is configured with blowout discs 180 that combine to provide a total area of approximately five square inches to allow airflow during normal operation. [48] In all of FIGS. 7A-7C, the blowout discs 180 are designed to release from the web metering device assembly 160 at a predetermined amount of air pressure differential on opposite sides of the blowout disc 180 and allow air to flow through the entire diameter of the through hole 130. In one embodiment, a predetermined amount of air pressure is established for release of a blowout disc 180. Accordingly, when the air pressure difference across the blowout disc 180 exceeds the predetermined amount, the blowout disc 180 is designed to release from the retaining ring 170 and allow the flow of air through the entire diameter of the through hole 130. In one embodiment, the blowout disc 180 is an ISODAMP® membrane or some similar membrane and the retaining ring 170 and base ring 210 are made from aluminum or plastic.

[49] As can be seen, the size of the cutout 90 in FIG. 7B is smaller than the size of the cutout 190 in FIG. 7C. Advantageously, various sizes of cutouts 190, various shapes of cutouts 190 and various numbers of cutouts 190 may be employed in the blowout discs 180 in order to accommodate the flow of more or less air during normal operation. Accordingly, in one example three circular metering device assemblies 160 having a desired combined airflow through their respective blowout discs 180 may be selected for a cabin space having a certain desired normal operation air flow volume according to the volume of airflow allowed by the combined cutouts 190. Similarly, a plurality of circular metering device assemblies 160 may be selected for a cabin space having a certain desired volume according to the combined normal operation airflow allowed by the combined cutouts 190 of the plurality of circular metering device assemblies 160 in the particular cabin space.

[50] FIG. 8A is an expanded view diagram illustrating an example web metering device assembly 160 according to an embodiment of the invention. In the illustrated embodiment, the web metering device assembly 160 comprises a base ring 210 and a retaining ring 170 comprising first and seconds parts 170A and 170B. The retaining ring 170 is secured to the base ring 210 by way of fasteners such as screws 220. The retaining ring 170 includes a recess 175 positioned to receive the blowout disc 180 and secure the blowout disc 180 between the retaining ring 170 and the base ring 210. The blowout disc 180 includes a cutout 190 to allow a predetermined amount of air flow to pass through the web metering device assembly 160 during normal operation. [51] FIG. 8B is a perspective view diagram illustrating an example assembled web metering device assembly 160 according to an embodiment of the invention. In the illustrated embodiment, the web metering device assembly 160 comprises a base ring 210 and a retaining ring 170 comprising first and seconds parts 170A and 170B. The retaining ring 170 is secured to the base ring 210 by way of fasteners such as screws 220. The retaining ring 170 includes a recess 175 positioned to receive the blowout disc 180 and secure the blowout disc 180 between the retaining ring 170 and the base ring 210. The blowout disc 180 includes a cutout 190 to allow a predetermined amount of air flow to pass through the web metering device assembly 160 during normal operation. The blowout disc also includes a lanyard that is secured at a first end to the blowout disc 180 and secured at a second end to the retaining ring 170 to prevent undesired travel of the blowout disc 180 after release of the blowout disc 180 during abnormal conditions.

[52] FIG. 8C is a perspective view diagram illustrating an alternative example web metering device assembly according to an embodiment of the invention. In the illustrated embodiment, the web metering device assembly 160 comprises a base ring 210 and a retaining ring 170 comprising a single part.

[53] FIG. 9 is a sectional view diagram of an example aircraft passenger cabin illustrating an example pair of frames 50 separated by a partially open crease beam web 120 with expanded views of example circular metering device assemblies 160 prior to installation according to an embodiment of the invention. In the illustrated embodiment, installed and/or unexpanded circular metering device assemblies 160 are positioned over weight reducing through holes 130 on each side of the frames 50 opposite the partially open crease beam web 120. In one embodiment, when the circular metering device assemblies 160 are installed, an adhesive layer is placed on the upper surface of the crease beam web 120 surrounding the weight reducing through holes 130 and/or on the lower surface of the base ring 210. These two surfaces are then brought into contact, for example with a cylindrical guide extending up from the through hole 130 to ensure that the inner surface of the base ring 210 is flush with the edge of the through hole 130 without blocking any portion of the through hole 130. Once the base ring 210 is secured to the crease beam web 120, then the blowout disc 180 may be placed on the base ring 210 and secured between the retaining rings 170A and 170B and the base ring 210 using a fastener such as a screw 220 with flat and lock washers. Advantageously, the blowout disc 180 may have a cutout 190.

[54] FIG. 10A is a sectional view diagram of an example aircraft passenger cabin illustrating a plurality of example circular metering device assemblies 160 installed over weight reducing holes in a crease beam web 120 according to an embodiment of the invention. In the illustrated embodiment, each of blowout discs 180 in the various circular metering device assemblies 160 have the same size cutout 190 in order to accommodate the desired amount of air flow in this section of the passenger cabin during normal operation. Additionally, in the illustrated embodiment, the base ring 210 comprises at least two segments.

[55] FIG. 10B is a sectional view diagram of an example aircraft passenger cabin illustrating a plurality of example circular metering device assemblies 160 installed over weight reducing holes in a crease beam web according to an embodiment of the invention. In the illustrated embodiment, blowout disc 180A comprises a cutout 190A having a first diameter, blowout disc 180B comprises a cutout 190B having a second diameter and blowout disc 180C does not include a cutout. Accordingly, the airflow allowed by blowout disc 180A during normal operation is a first volume flow rate, the airflow allowed by blowout disc 180B during normal operation is a second volume flow rate, and the airflow allowed by blowout disc 180C during normal operation is a third volume flow rate. In this embodiment, the third volume is zero. In one embodiment, the total amount of airflow desired across all circular metering device assemblies 160 installed in a particular area of an aircraft is determined by the size of the particular area.

[56] FIG. 1 1 is a sectional view diagram of an example aircraft passenger cabin illustrating an example truss structure frame bay 1 10 and example truss metering device assemblies 240 according to an embodiment of the invention. In the illustrated embodiment, the truss structure frame bay 1 10 comprises two truss structures 90 that are angled within the truss structure frame bay 1 10 to form an inverted V shape. Adjacent to the truss structure frame bay 1 10 on a first side is a frame 50 and adjacent the frame 50 in the same direction is a first truss metering device assembly 240 that is installed over a truss structure frame bay (not shown). Adjacent to the truss structure frame bay 1 10 on a second side is a frame 50 and adjacent the frame 50 in the same direction is a second truss metering device assembly 240 that is also installed over a truss structure frame bay (not shown). [57] FIG. 12 is an expanded view diagram illustrating an example truss metering device assembly 240 according to an embodiment of the invention. In the illustrated embodiment, the truss metering device assembly 240 comprises a metering plate assembly 250 that comprises a top plate 260 and a bottom plate 270. The top and bottom plates 260 and 270 secure between them one or more blowout discs 180. In the illustrated embodiment, there are three blowout discs 180 secured between the top and bottom plates 260 and 270. The top and bottom plates 260 and 270 can be secured to each other by way of fasteners such as screws. In one embodiment, the top and bottom plates 260 and 270 each comprise an aluminum sheet that includes one or more through holes.

[58] In one embodiment, the side of the top pate 260 that faces the bottom plate 270 includes a recess (not shown) that is machined into the aluminum and receives the perimeter edge of each of the one or more blowout discs 180. Alternatively, the side of the bottom pate 270 that faces the top plate 260 may include a recess (not shown) that is machined into the aluminum and receives the perimeter edge of each of the one or more blowout discs 180. In yet another alternative, the side of the top pate 260 that faces the bottom plate 270 and the side of the bottom pate 270 that faces the top plate 260 may each include a recess (not shown) that is machined into the aluminum and configured to receive the perimeter edge of each of the one or more blowout discs 180. In all cases, the one or more blowout discs 180 are positioned between the bottom pate 270 and the top plate 260, for example by fasteners that secure the top plate 260 to the bottom plate 270.

[59] In addition to the metering plate assembly 250, the truss metering device assembly 240 includes a housing 280 that may be separated into two or more parts. In the illustrated embodiment, the housing 280 comprises a first housing portion 280A and a second housing portion 280B. The housing 280 supports the metering plate assembly 250. In alternative embodiments, the housing 280 may be made from aluminum or plastic, for example ULTEM™ PEI plastic.

[60] The truss metering device assembly 240 additionally includes one or more bosses 290A and 290B extending from the housing 280 and positioned to guide one or more fasteners (e.g., screws) to secure the housing 280 to a companion bracket 300A and 300B. Advantageously, the brackets 300A and 300B are configured to engage a lower surface of the truss structure 90 and when the housing 280 is secured to the one or more brackets 300A and 300B by way of the fastener, the truss metering device assembly 240 is clamped to the truss structure 90 and thereby secured in the truss structure frame bay 1 10. In one embodiment, a lanyard 200 (not shown) is connected to the blowout disc 180 on a first end and connected to the top plate 260 or the bottom plate 270 on a second end.

[61] FIG. 13 is a sectional view diagram of an example aircraft passenger cabin illustrating an example truss structure frame bay 1 10 with expanded views of example truss metering device assemblies 240 prior to installation according to an embodiment of the invention. In the illustrated embodiment, the housing portion 280B is first secured to the truss structure 90 by screwing the housing 280B to the bracket 300B. Next, the housing portion 280A is secured to the housing 280B with screws and the housing 280A is secured to the truss structure 90 by screwing the housing 280A to the bracket 300A. Then the top plate and the bottom plate of the metering plate assembly 250 are screwed together to secure the blowout discs 180 between them and then the metering plate assembly 250 is screwed to the housing 280 to fully install the truss metering device assembly 240 in the truss structure frame bay 1 10.

[62] FIG. 14A is a sectional view diagram of an example aircraft passenger cabin illustrating a plurality of example truss metering device assemblies 240 installed over truss structure frame bays according to an embodiment of the invention. In the illustrated embodiment, each of blowout discs 180 in the various truss metering device assemblies 240 have the same size cutout 190 in order to accommodate the desired amount of air flow in this section of the passenger cabin during normal operation.

[63] FIG. 14B is a sectional view diagram of an example aircraft passenger cabin illustrating a plurality of example truss metering device assemblies 240 installed over truss structure frame bays according to an embodiment of the invention. In the illustrated embodiment, blowout disc 180A comprises a cutout 190A having a first diameter, blowout disc 180B comprises a cutout 190B having a second diameter and blowout disc 180C does not include a cutout. Accordingly, the airflow allowed by blowout disc 180A during normal operation is a first volume, the airflow allowed by blowout disc 180B during normal operation is a second volume, and the airflow allowed by blowout disc 180C during normal operation is a third volume. In this embodiment, the third volume is zero. In one embodiment, the total amount of airflow desired across a combination of truss metering device assemblies 240 installed in a particular area of an aircraft is determined by the total air volume size of the particular area of the aircraft.

[64] FIGS. 15A, 15B, 15C and 15D are plan view diagrams illustrating example configurations for a top plate 260 and bottom plate 270 of a metering plate assembly 250 according to embodiments of the invention. As shown in the illustrated embodiments, the plates in the metering plate assembly 250 may have zero, one or a plurality of through holes. In the complete metering plate assembly 250 as shown later in FIGS 16A-16H, blowout discs are secured between the top plate 260 and bottom plate 270 and partially or completely cover the through holes.

[65] In one embodiment, the top plate 260 and bottom plate 270 of the metering plate assembly 250 each have three through holes. Air flow is controlled by employing a combination of blowout discs having no cutout, a small cutout, a medium cutout or a large cutout. Variable sizes and custom sizes of cutouts may be employed in one or more blowout discs to match the characteristics of the area in which the air flow is being controlled by the combined airflow metering apparatuses deployed in the area. In one embodiment, each airflow metering apparatus is configured to achieve approximately 5 cubic inches of airflow per frame bay.

[66] FIGS. 16A, 16B, 16C, 16D, 16E, 16F, 16G and 16H are plan view diagrams illustrating example metering plate assemblies 250 for use in a truss metering device assembly according to embodiments of the invention. In each of the illustrated embodiments, the metering plate assembly 250 includes one or more blowout discs 180. Additionally, each blowout disc 180 may have zero or more cutouts 190. Advantageously, a desired combination of metering plate assemblies 250 with various configurations featuring multiple blowout discs 180 and the zero or more cutouts 190 can be selected to provide the desired amount of air flow in a particular section of the passenger cabin 20 during normal operation and the desired amount of increased air flow in the same section of the passenger cabin 20 during abnormal operation when the air pressure differential exceeds a predetermined threshold. The purpose of FIGS. 16A-16H is to illustrate that greater granularity of airflow control can be achieved using metering plate assemblies 250 with various configurations in the truss structure frame bays 1 10. [67] FIG. 17 is a plan view diagram illustrating an example private executive aircraft passenger cabin 20 with a system for aircraft passenger cabin airflow metering employing a plurality of airflow metering apparatuses according to an embodiment of the invention. In the illustrated embodiment, the passenger cabin 20 comprises one or more air ducts 300 and a plurality of discrete rooms 200A- 200E and common areas including galley and dining areas. The air duct 300 allows air to flow into the passenger cabin 20. Each of the discrete rooms 200A- 200E have a corresponding door 210A-210E that allow the room to be substantially sealed to prevent air from flowing between the respective room 200A-200E and the remainder of the passenger cabin 20. Advantageously, a plurality of airflow metering apparatuses comprising circular metering device assemblies 160 and truss metering device assemblies 240 are positioned throughout the cabin 20. Each of the airflow metering apparatuses comprises one or more blowout discs with or without cutouts to control airflow during normal operation. The airflow metering apparatuses are placed at the floor level along the outboard sidewall of the passenger cabin 20 during the custom buildout of the private executive aircraft. At any given location, the use of a truss metering device assembly 240 versus the use of one or more circular metering device assemblies 160 is determined by the configuration of the aircraft and the crease beam structure or truss structure that is present in any given frame bay opening.

[68] In the illustrated embodiment, the galley and room 200B each include a single truss metering device assembly 240 only. The remaining rooms and/or discrete areas of the cabin 20 include a combination of circular metering device assemblies 160 and truss metering device assemblies 240 as determined by the configuration of the aircraft.

[69] In each of the truss metering device assemblies 240, the number of blowout discs with cutouts and more specifically the combined size of the cutouts are determined based upon the desired volume of normal operation airflow in each of the rooms and/or discrete areas. Similarly, the number of circular metering device assemblies 160 with blowout discs having cutouts and more specifically the combined size of those cutouts are also determined based upon the desired volume of normal operation airflow in each of the rooms and/or discrete areas. In any given room and/or discrete area having plural airflow metering apparatuses (regardless of type), the number of blowout discs with cutouts and more specifically the combined size of the cutouts are determined based upon the desired volume of normal operation airflow.

[70] For example, each truss metering device assembly 240 may include one or more blowout discs, which each blowout disc optionally having cutouts of any specified size to allow for a desired amount of combined predetermined airflow during normal operation. Similarly, each web metering device assembly 160 may include a blowout disc that may optionally have a cutout of any specified size to allow for a desired amount of predetermined airflow during normal operation. Any additional frame bays that are not occupied by a fully closed crease beam web can be closed using a truss metering device assembly 240 with zero blowout discs or with one or more blowout discs having no cutout, or if the frame bay has a crease beam web with weight reducing holes, use one or more web metering device assembly 160 with a blowout disc having no cutout. Advantageously, by controlling the size of the openings in each truss structure frame bay and by controlling the size of the openings in each weight reducing through hole in a crease beam web, the system for aircraft passenger cabin airflow metering can implement precise control over the flow of air during normal operation in each discrete space within the passenger cabin 20 and the system for aircraft passenger cabin airflow metering can also implement precise control of the flow of air during abnormal operation when a change in air pressure causes one or more of the blowout discs to be released from its retaining mechanism.

[71] In one embodiment, the combined blowout discs 160 are selected such that the air entering the passenger cabin 20 via the one or more air ducts 300 and the air exhausted from the passenger cabin 20 via the combined through holes of the combined blowout discs 160 create a slightly positive pressure in the passenger cabin 20. This slightly positive pressure advantageously prevents, for example, smoke from entering the passenger cabin 20 from a non-passenger cabin 30 area.

[72] Additionally, the combined blowout discs 160 are positioned with respect to the one or more air ducts 300 and the plurality of discrete rooms 200A-200E and common areas including galley and dining areas to uniformly distribute conditioned air throughout the passenger cabin 20. Advantageously, by uniformly distributing the conditioned air throughout all portions of the passenger cabin 20, the temperature within the portions of the passenger cabin 20 can be uniformly maintained.

[73] The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles described herein can be applied to other embodiments without departing from the spirit or scope of the invention. Thus, it is to be understood that the description and drawings presented herein represent a presently preferred embodiment of the invention and are therefore representative of the subject matter which is broadly contemplated by the present invention. It is further understood that the scope of the present invention fully encompasses other embodiments that may become obvious to those skilled in the art and that the scope of the present invention is accordingly not limited.