Patent Description:
Commercial aircraft employ a cockpit door to provide a primary flight deck barrier between a cockpit of an aircraft and a passenger cabin. The cockpit door provides a barrier preventing unwanted entry into the cockpit during flight by non-authorized personnel.

In other terms, aircraft employ a flight deck door as a primary barrier protecting a flight deck (e.g., a cockpit) from unauthorized entry and/or intrusion. For instance, in a closed position, the primary barrier is designed to effectively withstand attacks from intruders and/or unauthorized entry. Thus, the primary barrier provides a primary secured area (e.g., the flight deck) when the primary barrier is in a closed position. However, a security threat can be presented during flight when the primary barrier is an open position to allow entry and/or exit of authorized personnel between the flight deck and a passenger cabin of the aircraft (e.g., when a flight attendant brings food or beverages for the pilots, etc.), when the pilot(s) use the lavatory (which is located outside of the flight deck and shared with passengers), etc. Thus, in some instances, a primary barrier in an open position during flight can present a security risk.

To reduce security risks when the primary barrier is in an open position during flight, aircraft often employ a secondary barrier. The secondary barrier forms a secondary secured area between a cabin area in which passengers are present and the primary barrier (e.g., a flight deck door). The secondary secured area provided by the secondary barrier often includes one or more monuments of an aircraft such as, for example, a lavatory, a closet, a galley, and/or other amenities that can be used by pilots or other authorized personnel during flight when the secondary barrier is in a secured position.

Typically, the secondary barrier is a secondary door that is attached to a frame. The frame attaches to the side walls and a ceiling of the aircraft and remains visible when the secondary door is in an open position and a closed position. For instance, the frame includes a first side that attaches to a first monument (e.g., a first wall), a second side that attaches to a second monument (e.g., a second wall) opposite the first monument, and a third side interconnecting the first side and the second side that attaches to the ceiling. The secondary door pivotally couples to the first side of the frame via one or more hinges and latches with the second side of the frame when the secondary door is in the closed position. These secondary doors, although effective at providing a secondary barrier, are visible when not in use and are aesthetically unappealing. Additionally, the frame and doors add significant weight to the aircraft. Document <CIT>, in accordance with its abstract, states an aircraft interior structure including a primary monument, an auxiliary monument, and a passenger seating section. The primary monument includes one or more storage compartments and a primary panel is configured to actuate between a primary panel stowed position and a primary panel deployed position. The auxiliary monument is spaced a select distance from the primary monument across a floor area of an aircraft cabin, and includes an auxiliary panel configured to actuate between an auxiliary panel stowed position and an auxiliary panel deployed position. Document <CIT>, in accordance with its abstract, states an aircraft equipped with an auxiliary access control barrier (AACB) to prevent access to an area of the aircraft. The AACB includes laterally extendable door panels that are slidably attached to each other to vary a width of the AACB, a hinge by which the door panels are pivotably attached to the aircraft, such that the door panels are pivotable between a deployed position, in which the door panels are positioned across the opening to prevent passage through the opening and in which the AACB has a first width, and a stowed position, in which the door panels are positioned to allow passage through the opening and in which the AACB has a second width, and one or more locks to prevent relative motion between the door panels to fix the width of the AACB and/or to secure the AACB within the opening in the bulkhead.

Presently claimed invention relates to a secondary barrier comprising: a plurality of tracks configured to mount to a first monument in a cabin of an aircraft; a plurality of rods, respective ones of the rods slidably engaging respective ones of the tracks; a panel coupled to respective ends of the rods, the rods being configured to move relative to the tracks between a stowed position and a deployed position corresponding to a stowed position and a deployed position of the secondary barrier, the panel in the deployed position being configured to interface with a second monument in the cabin opposite the first monument, in use the rods extending between the first monument and the second monument when the secondary barrier is in the deployed position. The panel is a metallic strip cap.

Presently claimed invention also relates to a method for making a secondary barrier in a cabin of an aircraft, comprising: attaching a plurality of tracks to a surface defining a cavity of at least one of a housing or a first monument of an aircraft cabin; slidably coupling a plurality of rods to corresponding ones of the tracks; and coupling a metallic strip cap to respective ends of the rods.

Certain examples are shown in the above-identified figures and described in detail below. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale or in schematic for clarity and/or conciseness. As used in this description, stating that any part is in any way positioned on (e.g., located on, disposed on, formed on, coupled to, etc.) another part, means that the referenced part is either in contact with the other part, or that the referenced part is spaced from the other part with one or more intermediate part(s) located therebetween. Stating that any part is in contact with another part means that there is no intermediate part between the two parts.

Wherever possible, the same reference numbers will be used throughout the drawing(s) and accompanying written description to refer to the same or like parts.

Example secondary flight deck barriers disclosed herein provide protection against security risks and significantly reduce weight compared to traditional secondary barriers. Additionally, example secondary flight deck barriers disclosed herein are not visible when stowed or not in use (e.g., in a closed position). Specifically, example secondary flight deck barriers disclosed herein are embedded or integrated in a structural component of the aircraft. In some examples, the secondary barriers disclosed herein are formed with and/or coupled to a monument of the aircraft cabin. Example secondary barriers disclosed herein provide a slide out gate movable between a use or deployed position and a non-use or stowed position relative to the a structural component (e.g., a monument or wall) of the aircraft to which the secondary flight deck barrier is coupled.

<FIG> illustrates an example aircraft <NUM> that can be implemented with a secondary barrier system in accordance with teachings of this disclosure. The aircraft <NUM> of the illustrated example includes a first aircraft wing <NUM> (e.g., a first airfoil) and a second aircraft wing <NUM> (e.g., a second airfoil) that extend from a fuselage <NUM>. A first aircraft engine <NUM> is supported by the first aircraft wing <NUM> and a second aircraft engine <NUM> is supported by the second aircraft wing <NUM>.

<FIG> is a top, partial cutaway view of an example interior or cabin <NUM> of the fuselage <NUM> of the aircraft <NUM> of <FIG>. The fuselage <NUM> of the illustrated example is implemented with an example secondary barrier <NUM> disclosed herein. The fuselage <NUM> of the illustrated example includes a passenger area <NUM> (e.g., a passenger cabin), a flight deck <NUM> and a crew area <NUM> between the passenger area <NUM> and the flight deck <NUM>. The crew area <NUM> includes a galley <NUM>, a closet <NUM>, a first lavatory <NUM>, a second lavatory <NUM> (e.g., an infant changing area) and/or other amenities that can be used by the flight crew and/or pilots. The crew area <NUM> is defined by a plurality of monuments <NUM> that include walls, cabinets, etc. Specifically, a first monument <NUM> and a second monument <NUM> form an aisle <NUM> that provides a pathway between the flight deck <NUM>, the crew area <NUM> and the passenger area <NUM>. The aisle <NUM> provides passengers located in the passenger area <NUM> access the crew area <NUM> to use one or more amenities located in the crew area <NUM>. Additionally, the aisle <NUM> provides access between the crew area <NUM> and the flight deck <NUM>. The first monument <NUM> of the illustrated example is a cabinet, wall, and/or other structure in the cabin <NUM>. Specifically, the first monument <NUM> is at least partially in the crew area <NUM>.

To restrict unauthorized access to the flight deck <NUM> during flight (e.g., via the aisle <NUM>), the aircraft <NUM> of the illustrated example includes a first or primary barrier <NUM>. As shown in the illustrated example, the primary barrier <NUM> is in an example closed position <NUM>. During flight, the primary barrier <NUM> is typically in the closed position <NUM>. The primary barrier <NUM> of the illustrated example is a flight deck door <NUM> that protects the flight deck <NUM> (e.g., a cockpit) from unauthorized entry and/or intrusion. For instance, the flight deck door <NUM> is designed to effectively withstand attacks from intruders and/or unauthorized entry into the flight deck <NUM>. In other words, the primary barrier <NUM> (e.g., the flight deck door <NUM>) provides a primary secured area <NUM> (e.g., the flight deck) when the primary barrier <NUM> is in the closed position <NUM>. Passengers in the passenger area <NUM> are prevented or restricted from accessing the flight deck <NUM> via the primary barrier <NUM>. When the primary barrier <NUM> is in the closed position <NUM>, the secondary barrier <NUM> can be positioned in a stowed position <NUM> as shown in <FIG> to allow access to amenities of the crew area <NUM> via the aisle <NUM>. In other words, when the secondary barrier <NUM> is in the stowed position <NUM>, passengers from the passenger area <NUM> can move freely into the aisle <NUM> to use the first lavatory <NUM>, the second lavatory <NUM>, and/or any other amenities in the crew area <NUM>.

<FIG> is a partial, cutaway view of the example aircraft <NUM> similar to <FIG> but shown with the primary barrier <NUM> in an example open position <NUM> and the secondary barrier <NUM> in an example deployed position <NUM>. During flight, the primary barrier <NUM> (e.g., the flight deck door <NUM>) can move to the open position <NUM> to allow flight deck crew in the flight deck <NUM> access to the crew area <NUM>. However, when the primary barrier <NUM> is in the open position <NUM> to allow entry and/or exit of authorized personnel between the flight deck <NUM> and the crew area <NUM>, the flight deck <NUM> can be exposed to the passenger area <NUM> of the aircraft <NUM>. Thus, moving the primary barrier <NUM> to the open position <NUM> during flight can cause a security risk in some instances.

To prevent or reduce a security risk when the primary barrier <NUM> is in the open position <NUM>, the aircraft <NUM> of the illustrated example includes the secondary barrier <NUM>. The secondary barrier <NUM> of the illustrated example is formed with or coupled to the first monument <NUM>. Specifically, the secondary barrier <NUM> of the illustrated example is slidably coupled to the first monument <NUM> and extends across the aisle <NUM> to engage the second monument <NUM> when the secondary barrier <NUM> is in the deployed position <NUM>. In some examples, the secondary barrier <NUM> can be slidably coupled to the second monument <NUM> and extends across the aisle <NUM> to engage the first monument <NUM> in a deployed position.

As described in greater detail below, the secondary barrier <NUM> extends across the aisle <NUM> between the first monument <NUM> and the second monument <NUM> to block or restrict access to the flight deck <NUM> via the aisle <NUM> (e.g., to prevent unauthorized access to the flight deck <NUM> when the primary barrier <NUM> is in the open position <NUM>). Thus, the secondary barrier <NUM> forms a secondary secured area <NUM> between the passenger area <NUM> in which passengers can be present and the crew area <NUM> (e.g., when the primary barrier <NUM> is in the open position <NUM>). In other words, the secondary secured area <NUM> includes the flight deck <NUM> and at least a portion of the aisle <NUM> of the crew area <NUM> leading to the primary barrier <NUM> and the flight deck <NUM>. The secondary barrier <NUM> secures (e.g., isolates) the flight deck <NUM> from the passenger area <NUM>. Thus, the secondary barrier <NUM> eliminates or prevents security risks and/or enables flight crew and/or other authorized personnel to use the first lavatory <NUM>, the closet <NUM> and/or other amenities during flight when the secondary barrier <NUM> is in the deployed position <NUM> and the primary barrier <NUM> is in the open position <NUM>. In some examples, the secondary barrier <NUM> can be positioned to the deployed position <NUM> when the primary barrier <NUM> is in the closed position <NUM> (<FIG>) to prevent or restrict access to the crew area <NUM> via the aisle <NUM>.

<FIG> is an exploded view of the example secondary barrier <NUM> disclosed herein. The secondary barrier <NUM> of the illustrated example is a gate <NUM>. Specifically, the gate <NUM> of the illustrated example is to be slidably coupled to the first monument <NUM> of the cabin <NUM>. In some examples, the secondary barrier <NUM> can be slidably coupled to the second monument <NUM> (<FIG>) and/or any other monument or structure of the aircraft <NUM>. The secondary barrier <NUM> of the illustrated example includes a plurality of rail assemblies <NUM>. The rail assemblies <NUM> include a plurality of tracks <NUM> (e.g., rails) and a plurality of rods <NUM>. The secondary barrier <NUM> includes a panel <NUM>. The tracks <NUM> are to mount to the first monument <NUM> of the passenger area <NUM>. For example, the tracks <NUM> of the illustrated example are coupled to (e.g., mounted in) an internal cavity <NUM> defined by an inner surface <NUM> of the first monument <NUM>. In some examples, the tracks <NUM> of the illustrated example can be fixed or mounted to the inner surface <NUM> via one or more fasteners (e.g., L-brackets, mounting brackets, clips, bolts, screws, clamps, and/or any other suitable fastener(s)). In some examples, the tracks <NUM> can be integrally formed with the first monument <NUM>. For instance, the tracks <NUM> can be formed by cutting slots, openings, channels and/or any other apertures in the first monument <NUM>. For example, the first monument <NUM> can be a solid structure (e.g., a solid wall formed without an internal cavity <NUM>) and the tracks <NUM> can be defined by a plurality of apertures or openings formed in the solid structure of the first monument <NUM>.

The rods <NUM> of the illustrated example slidably couple to the tracks <NUM>. Respective ones of the rods <NUM> slidably couple or slidably engage respective ones of the tracks <NUM>. The panel <NUM> is coupled (e.g., fixed) to respective ends <NUM> of the rods <NUM>. For example, the panel <NUM> can be welded, fastened and/or integrally formed with the respective ends <NUM> of the rods <NUM>. Thus, the rods <NUM> and the panel <NUM> move relative to the tracks <NUM>. In this manner, movement of the panel <NUM> causes movement of the rods <NUM> relative to the tracks <NUM>. The panel <NUM> of the illustrated example is a metallic strip cap. The tracks <NUM> and the rods <NUM> can be composed of metal, aluminum, titanium, plastic, alloy and/or any other material(s).

The tracks <NUM> of the illustrated example guide the rods <NUM> during movement. For example, the tracks <NUM> maintain a longitudinal axis <NUM> of the rods <NUM> in substantial alignment (e.g., horizontal or parallel alignment) with a longitudinal axis <NUM> of the tracks <NUM>. In other words, the tracks <NUM> maintain the longitudinal axis <NUM> of the rods <NUM> substantially parallel relative to the longitudinal axis <NUM> of the tracks <NUM>. As used herein, substantially parallel means perfectly parallel (e.g., zero degrees of deviation between the longitudinal axis <NUM> and the longitudinal axis <NUM>) and almost perfectly parallel (e.g., between <NUM> and <NUM> degrees of deviation between the longitudinal axis <NUM> and the longitudinal axis <NUM>). For instance, in the orientation of <FIG>, the longitudinal axis <NUM> and the longitudinal axis <NUM> are horizontal relative to the ground. Each of the tracks <NUM> of the illustrated example has a rectangular cross-sectional shape. In the illustrated example, the tracks <NUM> include a plurality of openings <NUM> to slidably receive the rods <NUM>. Each opening <NUM> has a circular cross-sectional shape. Each of the rods <NUM> of the illustrated example has a circular cross-sectional shape to interface with the openings <NUM> of the tracks <NUM>. For example, a diameter of each of the rods <NUM> is smaller than a diameter of each of the openings <NUM>. In other examples, the tracks <NUM>, the openings <NUM> and/or the rods <NUM> can have a square cross-sectional shape and/or any other cross-sectional shape.

As discussed in greater detail below, a first rail assembly <NUM> of the secondary barrier <NUM> includes a lock <NUM>. The lock <NUM> is to prevent movement of the secondary barrier <NUM> (e.g., and/or the rods <NUM> relative to the tracks <NUM>) when the secondary barrier <NUM> is in the deployed position <NUM>. The lock <NUM> of the illustrated example is formed by an interface between a first track 402a and a first rod 404a of the first rail assembly <NUM>. In some examples, a second rail assembly can include a lock (e.g., the lock <NUM>). In some examples, a third rail assembly and/or any number of rail assemblies <NUM> can include locks.

<FIG> is a cross-sectional side view of the secondary barrier <NUM> shown in the stowed position <NUM>. In the stowed position <NUM>, a respective one of the rods <NUM> is positioned (e.g., fully or completely positioned) in the opening <NUM> of a respective one of the tracks <NUM>. The tracks <NUM> maintain the rods <NUM> substantially parallel relative to the tracks <NUM> such that the longitudinal axis <NUM> of respective ones of the rods <NUM> is aligned (e.g., coaxially aligned) with the longitudinal axis <NUM> of respective ones of the tracks <NUM>. Additionally, the panel <NUM> of the illustrated example is recessed relative to the first monument <NUM>. For example, the first monument <NUM> includes a slot <NUM> to receive the panel <NUM>. In this manner, an outer surface <NUM> of the panel <NUM> is flush or aligned with a first wall or an outer surface <NUM> of the first monument <NUM>. To move the secondary barrier <NUM>, the panel <NUM> of the illustrated example includes a grip or handle <NUM>. The handle <NUM> of the illustrated example is a recess or recessed pocket formed in the panel <NUM> so that the handle <NUM> does not protrude outwardly or away from the outer surface <NUM> of the panel <NUM> (e.g., in a direction away from the rods <NUM> or the tracks <NUM>). Thus, the outer surface <NUM> of the panel <NUM> has a substantially flat surface. In the illustrated example, the lock <NUM> is in an unlocked position <NUM> to enable movement of the secondary barrier <NUM> to the deployed position <NUM>.

<FIG> is a cross-sectional side view of the secondary barrier <NUM> disclosed herein shown in the deployed position <NUM>. In the deployed position <NUM>, the panel <NUM> and the rods <NUM> extend from (e.g., the openings <NUM> of) the tracks <NUM> and/or from the first monument <NUM>. For instance, the rods <NUM> and/or the panel <NUM> extend in a direction (e.g., in a sideways direction <NUM>) away from the first monument <NUM> and the tracks <NUM>. The sideways direction <NUM> of the illustrated example is a direction along (e.g., a direction substantially parallel relative to) the longitudinal axis <NUM> of the tracks <NUM>. For instance, movement of the panel <NUM> away from the first monument <NUM> causes the rods <NUM> to move in a direction away from the tracks <NUM> along the longitudinal axis <NUM>. In other words, the rods <NUM> at least partially extend (e.g., extract) from the openings <NUM> of the tracks <NUM>.

In the deployed position <NUM> of the illustrated example, the lock <NUM> is in a locked position <NUM> to prevent movement of the secondary barrier <NUM> from the deployed position <NUM> to the stowed position <NUM>. In other words, the lock <NUM> prevents movement of the rods <NUM> relative to the tracks <NUM> from the deployed position <NUM> to the stowed position <NUM> when the lock <NUM> is in the locked position <NUM>. To enable the lock <NUM> to move to the locked position <NUM>, (e.g., an end of) the first rod 404a of the illustrated example is pivotally coupled to the panel <NUM> via a pivot <NUM> (e.g., a pivot joint, a ball joint, etc.). The pivot <NUM> enables the first rod 404a to pivot relative to the panel <NUM> such that a longitudinal axis <NUM> of the first rod 404a is angled relative to the longitudinal axis <NUM> of the rods <NUM> that do not include the lock <NUM>. In other words, the longitudinal axis <NUM> of the first rod 404a when the first rod 404a is in the deployed position <NUM> is angled relative to the longitudinal axis <NUM> of the first rod 404a when the first rod 404a is in the stowed position <NUM>. Thus, the first rod 404a, via the pivot <NUM>, enables at least a portion of the rod to move in a direction <NUM> in the orientation of <FIG> (e.g., a vertical direction, or a non-parallel or a perpendicular direction relative to the sideways direction <NUM>).

Thus, the lock <NUM> is movable between the locked position <NUM> and the unlocked position <NUM>. In the illustrated example, the lock <NUM> automatically moves to the locked position <NUM> when the secondary barrier <NUM> is in the deployed position <NUM>. However, the lock <NUM> is to be moved manually from the locked position <NUM> to the unlocked position <NUM> when the secondary barrier <NUM> moves from the deployed position <NUM> to the stowed position <NUM>.

The lock <NUM> is inconspicuous or concealed from view when the secondary barrier <NUM> is in the deployed position <NUM> as shown in <FIG>. For example, the first rod 404a has a slight taper of between approximately <NUM> degrees and <NUM> degrees from horizontal. This gradual taper can be difficult to detect by the human eye. Thus, although the first rod 404a may not be perfectly parallel relative to the other rods <NUM>, the first rod 404a can be indistinguishable from the other rods <NUM> when in the lock <NUM> is in the locked position. In some examples, a brush seal or other seal or cap can be positioned within the slot <NUM> to conceal the location of the lock. Such a seal can prevent identification of a location of the lock <NUM> (e.g., the first rod 404a) by a passenger in the passenger area <NUM>. Thus, only authorized personnel would be able to determine which one of the rods <NUM> includes the lock <NUM>.

In some examples, a control system can be employed to automatically move the secondary barrier <NUM> between the deployed position <NUM> and the stowed position <NUM>. In some examples, the control system can be employed to move the secondary barrier <NUM> between the stowed position <NUM> and the deployed position <NUM> based on a position of the primary barrier <NUM>. Additional details of how the lock <NUM> moves between the locked position <NUM> and the unlocked position <NUM> are described below in <FIG>, <FIG>.

<FIG> is partial, perspective view of the example crew area <NUM> of <FIG> with the secondary barrier <NUM> shown in the example stowed position <NUM>. In the stowed position <NUM>, the secondary barrier <NUM> is positioned within the first monument <NUM> of the crew area <NUM>. Specifically, the rods <NUM> are positioned inside the first monument <NUM> when the secondary barrier <NUM> is in the stowed position <NUM>. For instance, the rods <NUM> and the tracks <NUM> are completely positioned within the first monument <NUM> and are not visible to passengers in the passenger area <NUM> (<FIG>). In some examples, the only portion of the secondary barrier <NUM> that is visible to passengers in the passenger area <NUM> when the secondary barrier <NUM> is in the stowed position <NUM> is the outer surface <NUM> of the panel <NUM>. In other words, the secondary barrier <NUM> is hidden from view when in the stowed position <NUM> and, thus, is aesthetically appealing.

The panel <NUM> of the illustrated example is flush relative to the outer surface <NUM> of the first monument <NUM>. In this manner, the outer surface <NUM> of the panel <NUM> and the outer surface <NUM> of the first monument <NUM> form a substantially continuous overall outer surface or first wall <NUM> (e.g., an outer wall) when the secondary barrier <NUM> is in the stowed position <NUM>. As used herein, "substantially continuous" means that the outer surface <NUM> of the panel <NUM> and the first wall <NUM> of the first monument <NUM> do not form a raised surface or discontinuous surface at or across an interface <NUM> between the panel <NUM> and the first monument <NUM>. In other words, the outer surface <NUM> of the first monument <NUM> and the outer surface <NUM> of the panel <NUM> define the first wall <NUM> of the first monument <NUM>. Thus, the panel <NUM> is to define at least a portion of the first wall <NUM> of the first monument <NUM> when the secondary barrier <NUM> is in the stowed position <NUM>. In the stowed position <NUM>, the secondary barrier <NUM> enables access to the crew area <NUM> via the aisle <NUM>.

<FIG> is another partial, perspective view of the crew area <NUM> of the example aircraft <NUM> of <FIG>. Specifically, a second surface or second wall <NUM> of the second monument <NUM> of the crew area <NUM> is shown in <FIG>. The second wall <NUM> of the second monument <NUM> is opposite the outer surface <NUM> of the first monument <NUM>. In the deployed position <NUM>, the secondary barrier <NUM> engages the second surface of the second monument <NUM>.

<FIG> is a side view of the example crew area <NUM> with the secondary barrier <NUM> shown in the deployed position <NUM>. As noted above, the secondary barrier <NUM> is movable relative to the first monument <NUM> between the deployed position <NUM> and the stowed position <NUM>. Specifically, the secondary barrier <NUM> is to extend between the first wall <NUM> (<FIG>) or the outer surface <NUM> of the first monument <NUM> and the second wall <NUM> (<FIG>) opposite the first wall <NUM>. In the deployed position <NUM>, the panel <NUM> interfaces with the second monument <NUM> opposite the first monument <NUM>. In the deployed position <NUM>, the rods <NUM> extend between the first monument <NUM> and the second monument <NUM>. The second wall <NUM> provides a brace for the panel <NUM> when the secondary barrier <NUM> is in the deployed position <NUM>. In other words, the secondary barrier <NUM> (e.g., the gate <NUM>) extends between the first monument <NUM> and the second monument <NUM> to block access to the primary barrier <NUM> via the aisle <NUM>. As further described in <FIG>, <FIG>, the lock <NUM> prevents movement of the secondary barrier <NUM> between the deployed position <NUM> and the stowed position <NUM> when the lock <NUM> is in the locked position <NUM> (<FIG>).

<FIG> is a perspective, exploded view of the first rail assembly <NUM> and the lock <NUM> of <FIG>. <FIG> is a perspective view of the first rail assembly <NUM> and the lock <NUM> shown in the unlocked position <NUM>. The lock <NUM> of the illustrated example is formed (e.g., integrally formed) with the first rod 404a and the first track 402a. Specifically, the lock <NUM> is formed by a keyed interface <NUM> defined by the first rod 404a and the first track 402a associated with the first rod 404a. The keyed interface <NUM> includes a protrusion <NUM> formed on the first rod 404a and an opening <NUM> formed in the first track 402a. The protrusion <NUM> of the illustrated example is an annular cylindrical or body <NUM> formed on an outer surface <NUM> of the first rod 404a. For example, the outer surface <NUM> of the first rod 402a has a first diameter <NUM> (<FIG>) and the protrusion <NUM> has a second diameter <NUM> (<FIG>) greater than the first diameter <NUM>. The protrusion <NUM> of the illustrated example includes a stop <NUM> (e.g., a flat surface) and a tapered portion <NUM>.

The opening <NUM> includes a first aperture <NUM> and a second aperture <NUM>. The first aperture <NUM> and the second aperture <NUM> form a key-hole shape. The first aperture <NUM> is sized (e.g., has a diameter) to enable the protrusion <NUM> to pass through the opening <NUM>. The second aperture <NUM> is sized (has a diameter or area) to prevent passage of the protrusion <NUM> through the opening <NUM>. Thus, the first aperture <NUM> has a first area (e.g., diameter) that is greater than the first diameter <NUM> of the first rod 404a and the second diameter <NUM> of the protrusion <NUM>. Additionally, the second aperture <NUM> has a second area (e.g., a diameter) that is less than the second diameter <NUM> of the protrusion and greater than the first diameter <NUM> of the first rod 404a. The second aperture <NUM> enables the first rod 404a to move relative to the first track 402a in the direction <NUM> non-parallel (e.g., perpendicular to or vertical) relative to the longitudinal axis <NUM> of the first track 402a.

During operation, the opening <NUM> (<FIG> and <FIG>) of the first track 402a maintains or guides the first rod 404a in substantial alignment (e.g., coaxial alignment) with the first aperture <NUM> until the protrusion <NUM> exits the opening <NUM> of the first track 402a. As the protrusion <NUM> exits the opening <NUM> of the first track 402a via the first aperture <NUM>, an end <NUM> of the first rod 404a moves in the direction <NUM> and into the second aperture <NUM> to the locked position <NUM>. For example, gravity can automatically cause the end <NUM> of the first rod 404a to move into the second aperture <NUM> as the protrusion <NUM> exits the first track 402a. In the locked position <NUM>, the stop <NUM> (e.g., a flat surface or an end of the protrusion <NUM>) engages an outer surface <NUM> of the first track 402a, providing an interference to prevent movement of the first rod 404a toward the stowed position <NUM> along the longitudinal axis <NUM> of the first track 402a. The first track 402a prevents movement of the first rod 404a toward the stowed position <NUM> when the stop (e.g., an end) of the protrusion <NUM> is in direct engagement with the outer surface <NUM> of the first track 402a adjacent the second aperture <NUM>.

<FIG> is a cross-sectional side view of the first rail assembly <NUM> with the lock <NUM> shown in the unlocked position <NUM>. <FIG> is a cross-sectional side view of the first rail assembly <NUM> shown with the lock <NUM> in the locked position <NUM>. The lock <NUM> prevents movement of the secondary barrier <NUM> in the direction <NUM> parallel relative to the longitudinal axis <NUM> of the first track 402a when the secondary barrier <NUM> is in the deployed position <NUM>. In operation, the first rod 404a is to allow movement of the secondary barrier <NUM> from the deployed position <NUM> to the stowed position <NUM> when the longitudinal axis <NUM> of the first rod 404a is substantially parallel and/or substantially aligned (e.g., exactly coaxially aligned or approximately coaxially aligned) relative to the longitudinal axis <NUM> of the first track 402a. The first rod 404a is to prevent movement of the secondary barrier <NUM> from the deployed position <NUM> to the stowed position <NUM> when the longitudinal axis <NUM> of the first rod 404a is not substantially parallel (e.g., is non-parallel or at an angle that is greater than between <NUM> degree and <NUM> degrees) relative to the longitudinal axis <NUM> of the first track 402a. When the protrusion <NUM> of the first rod 1002a exits the opening <NUM> of the first track 402a, the first rod 404a moves (e.g., automatically via gravity) in the direction <NUM> non-parallel (e.g., a downward direction in the orientation of <FIG>) relative to the longitudinal axis <NUM> of the first track 402a to move the lock <NUM> from the unlocked position <NUM> to the locked position <NUM>. For example, the end <NUM> of the first rod 404a moves from the first aperture <NUM> to the second aperture <NUM> of the opening <NUM> (<FIG>). In the locked position <NUM>, the stop <NUM> of the protrusion <NUM> engages (e.g., directly engages) the outer surface <NUM> of the first track 402a to prevent movement of the first rod 404a relative to the first track 402a.

To move the lock <NUM> to the unlocked position <NUM> and move the secondary barrier <NUM> to the stowed position <NUM>, the first rod 404a is moved in the direction <NUM> (e.g., non-parallel or perpendicular) relative to the longitudinal axis <NUM> of the first track 402a. Specifically, the end <NUM> of the first rod 404a is moved in upward in the orientation of <FIG> to align (e.g., coaxially align) the longitudinal axis <NUM> of the first rod 404a and the longitudinal axis <NUM> of the first track 402a. In other words, the first rod 404a is repositioned to align with the first aperture <NUM> of the opening <NUM>. In some examples, a user (e.g., a pilot, authorized personnel) can move the first rod 404a manually in the direction <NUM> to move the lock <NUM> from the locked position <NUM> to the unlocked position <NUM>.

In some examples, the lock <NUM> can operate (e.g., be positioned) between the locked position <NUM> and the unlocked position <NUM> via a control system that includes a controller and a motor (e.g., an actuator) operatively coupled to the lock <NUM> that can move the secondary barrier <NUM> in the direction <NUM> (e.g., a sideways direction) via a transmission or gear train and/or move the first rod 404a in the direction <NUM> between the locked position <NUM> and the unlocked position <NUM>. In some examples, the control system can automatically move the secondary barrier <NUM> to the stowed position <NUM> when the primary barrier <NUM> is in the closed position <NUM>. In some examples, the control system can automatically move the secondary barrier <NUM> to the deployed position <NUM> when the primary barrier <NUM> moves to the open position <NUM>. In some examples, the lock <NUM> can be an actuator (e.g., a hydraulic or air operated actuator) that can maintain or lock the secondary barrier <NUM> in the deployed position <NUM> and prevent unauthorized movement of the secondary barrier <NUM> toward the stowed position <NUM> when the primary barrier <NUM> (<FIG>) is in the open position <NUM>. In such examples, the lock <NUM> is not formed by a keyed interface. Additionally, although the first rod 404a of the illustrated example can pivot to move the end <NUM> in the direction <NUM> (e.g., a vertical direction) to move the lock <NUM> between the unlocked position <NUM> and the locked position <NUM>, the first rod 404a maintains a substantially straight profile relative to the other rods <NUM> so that the lock <NUM> is discrete. Thus, only authorized personnel would be informed of which one of the rods <NUM> of the secondary barrier <NUM> includes the lock <NUM>. In some examples, two or more rods <NUM> can include the lock <NUM>. In some examples, a user input (e.g., a pin code via a keypad, facial recognition, etc.) can be provided to enable movement of the lock <NUM> from the locked position <NUM> to the unlocked position <NUM>.

<FIG> is a perspective view of the second monument <NUM> of the aircraft <NUM> of <FIG>. <FIG> is a top view of <FIG>. Specifically, a retainer <NUM> is provided on the second wall <NUM> of the second monument <NUM>. For example, the retainer <NUM> is fastened or attached to a frame of the second monument <NUM> via one or more fasteners, a weld, etc. The retainer <NUM> of the illustrated example is to interface with the panel <NUM> to retain the panel <NUM> and, thus, the secondary barrier <NUM> in the deployed position <NUM>. Additionally, the retainer <NUM> prevents or restricts movement of the secondary barrier <NUM> in a fore-aft direction <NUM> (e.g., a horizontal direction toward the primary barrier <NUM> of <FIG>). For example, the fore-aft direction <NUM> is substantially perpendicular (e.g., perfectly perpendicular or within <NUM> degree of perfect perpendicularity) relative to the direction <NUM> (e.g., the sideways direction) and the direction <NUM> (e.g., the vertical direction) of <FIG>. Additionally, the retainer <NUM> of the illustrated example restricts movement of the secondary barrier <NUM> toward the stowed position <NUM> when the retainer <NUM> retains the secondary barrier <NUM> in the deployed position <NUM>. In some examples, the retainer <NUM> and the panel <NUM> provide a lock interface <NUM>. For example, the lock interface <NUM> can include an aperture <NUM> formed through a portion <NUM> of the retainer <NUM> and a lip <NUM> of the panel <NUM> to receive a shackle of a lock (e.g., a pad lock). In some such examples, the lock interface <NUM> is omitted. The retainer <NUM> of the illustrated example includes a base <NUM> and side walls <NUM> protruding from the base <NUM> to define a cavity <NUM> that receives the panel <NUM>.

<FIG> is a top view of a portion of an aircraft cabin <NUM> of an aircraft <NUM> implemented with another example secondary barrier <NUM> (e.g., a gate) disclosed herein. In the illustrated example, the secondary barrier <NUM> is a barrier module <NUM> (e.g., a unitary unit or assembly). In some examples, the barrier module <NUM> can be retrofit to aircraft in the field. The secondary barrier <NUM> of the illustrated example includes a housing <NUM> that couples (e.g., attaches) to a monument <NUM> (e.g., the first monument <NUM>, a wall, etc.) of the aircraft <NUM>. Thus, the secondary barrier <NUM> of the illustrated example is a self-contained unit or assembly that can be installed in an aircraft by attaching the housing <NUM> to a first wall <NUM> of the aircraft cabin <NUM>. The secondary barrier <NUM> prevents access to a primary barrier <NUM> via an aisle <NUM> when the primary barrier is an open position <NUM> and the secondary barrier <NUM> is in a deployed position <NUM>. In the deployed position <NUM>, the secondary barrier <NUM> extends from the housing <NUM> across the aisle <NUM> and engages a second wall <NUM> of a second monument <NUM>.

<FIG> is a perspective view of the secondary barrier <NUM> shown in an example stowed position <NUM>. <FIG> is a perspective view of the secondary barrier <NUM> shown in the example deployed position <NUM>. Referring to <FIG>, the secondary barrier <NUM> includes a plurality of tracks <NUM> and a plurality of rods <NUM> (e.g., defining a gate). The tracks <NUM> of the illustrated example are positioned within the housing <NUM>. Specifically, the tracks <NUM> of the illustrated example are slots or openings formed in the housing <NUM> between a first side edge <NUM> and a second side edge <NUM> opposite the first side edge <NUM>. Respective ones of the rods <NUM> slidably couple to respective ones of the tracks <NUM>. A panel <NUM> is coupled to respective ends of the rods <NUM>. The panel <NUM> enables movement of the rods <NUM> relative to the tracks <NUM> between the stowed position <NUM> and the deployed position <NUM>. The rods <NUM> in the stowed position <NUM> are positioned entirely (e.g., completely) within the housing <NUM> (e.g., such that the rods <NUM> are not visible to a passenger in a passenger area of the aircraft <NUM>). The rods <NUM> in the deployed position extend externally from the housing <NUM>. The panel <NUM> is an extension of the housing <NUM> and defines an outer wall <NUM> of the housing <NUM> when the panel <NUM> is in the stowed position <NUM>. In some examples, the secondary barrier <NUM> includes a lock (e.g., the lock <NUM>) to prevent movement of the panel <NUM> relative to the housing <NUM> when the panel <NUM> is in the deployed position <NUM> and the lock is in a locked condition. The lock can be provided by a key interface (e.g., the key interface or lock <NUM> of <FIG>) formed between a first rod 1406a and a first track 1404a. In some examples, operation of the secondary barrier <NUM> can be controlled by a control system operatively coupled to the secondary barrier <NUM>.

<FIG> is a flowchart representative of a method for forming or installing a secondary barrier in an aircraft. The installation process described can be performed during manufacturing of an aircraft or retrofitting existing aircraft in the field. The method begins at block <NUM> by attaching a plurality of tracks <NUM> to a surface defining a cavity of at least one of a housing <NUM> or a monument (e.g., the first monument <NUM>) located in an aircraft cabin <NUM>, <NUM> of an aircraft <NUM>, <NUM>. In some examples, the cavity is formed in the first monument <NUM> of the aircraft <NUM>. In some examples, a plurality of slots or openings <NUM> are formed in (e.g., the first wall <NUM>) the first monument <NUM> to receive respective ones of the tracks <NUM>. The tracks <NUM> can be attached via fasteners, brackets, welding, chemical fasteners, and/or any other fasteners. In some examples, the tracks <NUM> can be integrally formed with the at least one of the housing <NUM> or the first monument <NUM>. After the tracks <NUM>, <NUM> are installed, a plurality of rods <NUM>, <NUM> are slidably coupled to corresponding ones of the tracks <NUM>, <NUM>. (block <NUM>). A panel <NUM>, <NUM> is then coupled to respective ends of the rods <NUM>, <NUM> (block <NUM>). In some examples, a recess or a slot <NUM> is formed in the housing <NUM> or the first monument <NUM> to enable the panel <NUM>, <NUM> to flush mount with the at least one of the housing <NUM> or the first monument <NUM> when the secondary barrier <NUM>, <NUM> is in the stowed position <NUM>, <NUM>. In some examples, a retainer <NUM> is attached to the second wall <NUM> of a second monument <NUM> of a cabin <NUM> opposite the first monument <NUM>.

Although each example secondary barrier <NUM> and <NUM> disclosed above has certain features, it should be understood that it is not necessary for a particular feature of one example to be used exclusively with that example. Instead, any of the features described above and/or depicted in the drawings can be combined with any of the examples, in addition to or in substitution for any of the other features of those examples, insofar as the resulting example remains within the scope of the appended claims. Features of one example are not mutually exclusive to features of another example. In some examples, the secondary barrier <NUM> can be used in conjunction with the secondary barrier <NUM>. In some examples, one or more of the components of the secondary barrier <NUM> (e.g., the retainer <NUM>, the lock <NUM>, etc.) can be used with the secondary barrier <NUM>.

As used herein in the context of describing structures, components, items, objects and/or things, the phrase "at least one of A and B" is intended to refer to implementations including any of (<NUM>) at least one A, (<NUM>) at least one B, and (<NUM>) at least one of A and at least one of B. As used herein in the context of describing the performance or execution of processes, instructions, actions, activities and/or steps, the phrase "at least one of A and B" is intended to refer to implementations including any of (<NUM>) at least A, (<NUM>) at least B, and (<NUM>) at least A and at least B. Similarly, as used herein in the context of describing the performance or execution of processes, instructions, actions, activities and/or steps, the phrase "at least one of A or B" is intended to refer to implementations including any of (<NUM>) at least A, (<NUM>) at least B, and (<NUM>) at least A and at least B.

From the foregoing, it will be appreciated that the disclosed secondary barriers improve aircraft safety while improving aircraft efficiency by reducing aircraft weight. Additionally, example secondary barriers disclosed herein improve aircraft aesthetics by providing a gate or door-like retractable structure that is not visible when the secondary barrier is in a stowed or open position. Unlike traditional secondary barriers, the secondary barriers disclosed herein do not include a frame that is visible when the secondary barrier is in a non-use position (e.g., an open or a stowed position).

Claim 1:
A secondary barrier (<NUM>, <NUM>) comprising:
a plurality of tracks (<NUM>, 402a, <NUM>, 1404a) configured to mount to a first monument (<NUM>, <NUM>, <NUM>) in a cabin (<NUM>, <NUM>) of an aircraft (<NUM>, <NUM>);
a plurality of rods (<NUM>, 404a, <NUM>, 1406a), respective ones of the rods (<NUM>, <NUM>) to slidably engage respective ones of the tracks (<NUM>, 402a, <NUM>, 1404a);
a panel (<NUM>, <NUM>) coupled to respective ends of the rods (<NUM>, 404a, <NUM>, 1406a), the rods (<NUM>, 404a, <NUM>, 1406a) being configured to move relative to the tracks (<NUM>, 402a, <NUM>, 1404a) between a stowed position (<NUM>, <NUM>) and a deployed position (<NUM>, <NUM>) corresponding to a stowed position (<NUM>,<NUM>) and a deployed position (<NUM>, <NUM>) of the secondary barrier (<NUM>, <NUM>), the panel (<NUM>, <NUM>) in the deployed position (<NUM>, <NUM>) being configured to interface with a second monument (<NUM>, <NUM>, <NUM>) in the cabin opposite the first monument (<NUM>, <NUM>, <NUM>), in use the rods (<NUM>, 404a, <NUM>, 1406a) being configured to extend between the first monument (<NUM>, <NUM>, <NUM>) and the second monument (<NUM>, <NUM>, <NUM>) when the secondary barrier (<NUM>, <NUM>) is in the deployed position (<NUM>, <NUM>),
wherein the panel (<NUM>, <NUM>) is a metallic strip cap.