Patent Publication Number: US-9421406-B2

Title: Freighter cargo fire protection

Description:
TECHNICAL FIELD 
     The present teachings relate to the field of fire protection and, more particularly, to a system for suppressing and containing fire during transportation of cargo in a cargo freighter such as an aircraft. 
     BACKGROUND 
     The frequency of aircraft freighter main deck cargo fires has increased over the years. Recent NTSB Safety Recommendations to the FAA (Nov. 28, 2012 A-12-68 through 70) suggest various guidelines, including: developing and implementing fire detection system performance requirements for the early detection of fires originating within cargo containers and pallets (A-12-68). (This safety recommendation supersedes Safety Recommendation A-07-98, which is classified “Closed-Acceptable Action/Superseded.”); ensuring that cargo container construction materials meet the same flammability requirements as all other cargo compartment materials in accordance with Title 14 Code of Federal Regulations 25.855. (A-12-69); and requiring the installation and use of active fire suppression systems in all aircraft cargo compartments or containers, or both, such that fires are not allowed to develop (A-12-70). 
     Conversion of passenger aircraft to freighter aircraft is a common practice. Passenger aircraft typically includes a cargo hold or deck for transporting passenger baggage and other cargo and a main deck for transporting passengers. The cargo deck of a passenger aircraft typically includes smoke detection and fire suppression, for example using smoke and/or heat detectors for fire detection and an extinguishing gas or retardant source such as one or more Halon or other fire retardant canisters for dispersion of suppressant. Passenger deck fire suppression typically includes hand-held fire extinguishers delivered by an operator. System level fire protection with the use of an extinguishing gas source in a passenger cabin is not standard practice as this environment is an occupied space and use of portable fire extinguisher is common practice. 
     Conversion of passenger aircraft to freighter aircraft is a common practice. Passenger aircraft typically include a cargo hold for transporting passenger baggage other cargo and a main deck for transporting passengers. The cargo hold of a passenger aircraft typically includes a system for detecting fires, for example using smoke and/or heat detectors inside the cargo hold, and a system for controlling fires through use of fire resistant materials, reducing airflow, and flooding the entire cargo hold with active fire suppressing or inert gases that are remotely discharged from the flight deck. The passenger compartment on the main deck typically relies on the flight crew for fire detection, with the exception of certain spaces such as lavatories and, in some cases, galleys. Fire suppression in the passenger compartment typically uses hand held portable extinguishers operated by the flight crew. A total flooding approach to fire suppression in a passenger compartment is not typically standard practice as this space is occupied by humans. 
     Conversion of a passenger aircraft to an aircraft that can carry freight in place of passengers on the main deck typically includes the addition of a fire or smoke detection system, fire resistant main deck cargo liners, and a way to deprive the fire of oxygen to control the fire. Fire protection within existing cargo holds is not typically modified during conversion of the aircraft from a passenger plane to a freighter. Freighter aircraft have typically used decompression of the main deck cargo space as the technique to deprive the fire of oxygen, this approach is commonly referred to as passive fire suppression. For decompression to be an effective technique for controlling a main deck fire, the aircraft must be flying at an altitude high enough that the oxygen is forced out of the aircraft and the ambient oxygen available is insufficient to allow the fire to grow. Typically, the minimum altitude used for effectively controlling a main deck fire is 25,000 feet above sea level. The overall effectiveness of this approach has been questioned (reference the NTSB Safety Recommendations discussed above), as the aircraft must eventually descend to land, which increases oxygen levels and can cause the smoldering fire to reignite and expand out of control. The NTSB has thus recommended the addition of an active fire suppression system to the main deck fire protection scheme of freighter aircraft. 
     To apply the same total flooding active fire suppression techniques on the main deck that are used for the standard cargo holds of passenger aircraft is problematic due to the large volume of the main deck cargo compartment relative to the cargo holds of the lower deck. The weight of a fire detection and suppression system increases with the volume of area to be protected, for example because the volume of gas is increased. Aviation products/systems are particularly sensitive to increased weight, for example because the cost of hourly operation from fuel and other costs increases as payload weight increases. 
     For example, an initial discharge system (i.e., high rate discharge, HRD) for a lower deck cargo hold of a 747-400 may require about 110 pounds of Halon to achieve a 6.8% maximum concentration forward and 6.2% aft. This quantity of Halon provides a 5% Halon concentration in about 2 minutes and a maximum concentration in about 3 minutes. A metered discharge system (i.e., low rate discharge, LRD) for a cargo deck may require about 160 pounds of Halon to achieve a sustained concentration of about 3.7% forward for a sustained duration of about 3% for a duration of greater than 195 minutes. An HRD system for a main deck of a 747-400 may require about 294 pounds of Halon to achieve a 7.0% maximum concentration. This quantity of Halon provides a 5% Halon concentration in about 40 seconds and a maximum concentration in about 1 minute. An LRD system for the main deck may require about 920 pounds of Halon to achieve a sustained concentration of about 3.2% for a duration of greater than 90 minutes. Halon gross weight for the 747-400 is about 410 pounds for the lower deck cargo holds and about 1680 pounds for the main deck. 
     A fire suppression system and method is disclosed in US Pat. Pub. 2010/0236796, which is incorporated herein by reference in its entirety. 
     A fire suppression and containment system that assists in meeting these recommendations, improves detection time for smoke/ fires, reduces fire damage, and decreases weight compared to some other fire protection systems would be desirable. 
     SUMMARY 
     The following presents a simplified summary in order to provide a basic understanding of some aspects of one or more embodiments of the present teachings. This summary is not an extensive overview, nor is it intended to identify key or critical elements of the present teachings nor to delineate the scope of the disclosure. Rather, its primary purpose is merely to present one or more concepts in simplified form as a prelude to the detailed description presented later. 
     In an embodiment, a fire suppression system for an aircraft including at least a first deck and a second deck may include a fire retardant source and a first fire suppression system component for the first deck. The first fire suppression system component may include a plurality of first sensors on the first deck for detecting a fire and a plurality of first retardant nozzles on the first deck, wherein each first retardant nozzle is in fluid communication with the fire retardant source and at least one first retardant nozzle is paired with one of the first sensors. The fire suppression system may further include a second fire suppression system component for the second deck, including a plurality of second sensors on the second deck for detecting a fire and a plurality of second retardant nozzles on the second deck, wherein each second retardant nozzle is in fluid communication with the fire retardant source and at least one second retardant nozzle is paired with one of the second sensors. 
     In another embodiment, a fire suppression system may include a fire retardant source, a primary release valve in fluid communication with the fire retardant source, a first conduit and a second conduit each in fluid communication with the primary release valve, and a first fire suppression system component for a first deck in fluid communication with the first conduit. The first fire suppression system component may include a plurality of first deck sensors for detecting a fire, a plurality of first deck secondary release valves, wherein each first deck secondary release valve is uniquely paired with one of the plurality of first deck sensors, and a plurality of first deck fire retardant delivery nozzles, wherein each first deck fire retardant delivery nozzle is uniquely paired with one of the plurality of first sensors. The fire suppression system may further include a second fire suppression system component for a second deck in fluid communication with the second conduit, the second fire suppression system component including a plurality of second deck sensors for detecting a fire, a plurality of second deck secondary release valves, wherein each second deck secondary release valve is uniquely paired with one of the plurality of second deck sensors, a plurality of second deck fire retardant delivery nozzles, wherein each second deck fire retardant delivery nozzle is uniquely paired with one of the plurality of second sensors. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present teachings and together with the description, serve to explain the principles of the disclosure. In the figures: 
         FIG. 1  is a schematic plan view of a fire protection system for two or more freighter decks, such as a main deck and a cargo deck; 
         FIG. 2  is a schematic plan view of a fire protection system component for a deck of a cargo freighter; 
         FIG. 3A  is a schematic cross section of a portion of the  FIG. 2  depiction, and  FIG. 3B  is a schematic cross section of another embodiment; 
         FIGS. 4A-4C  are schematic cross sections of a valve that can be used in an embodiment of the present teachings; 
         FIG. 5  is a perspective depiction of a cargo or shipping container in accordance with an embodiment of the present teachings; and 
         FIGS. 6A and 6B  are cross sections of a heat detector (fire detector) in accordance with an embodiment of the present teachings. 
     
    
    
     It should be noted that some details of the FIGS. have been simplified and are drawn to facilitate understanding of the present teachings rather than to maintain strict structural accuracy, detail, and scale. 
     DETAILED DESCRIPTION 
     Reference will now be made in detail to exemplary embodiments of the present teachings, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
     One or more embodiments of the present teachings may result in a fire protection system, for example a fire detection and suppression system, that more quickly detects a fire within a freighter bay than some prior systems. In an embodiment, a fire suppression system may more precisely disperse a fire retardant to a required location than is found with some systems, for example systems that flood an entire open space with retardant. Further, a fire suppression system in accordance with an embodiment of the present teachings may have a reduced weight compared to some other fire suppression systems, thereby decreasing freighter operational costs. An embodiment of the present teachings may include one or more of several elements of the present teachings as described below. 
       FIG. 1  depicts a fire suppression system  10  in accordance with an embodiment of the present teachings. As depicted in  FIG. 1 , a fire retardant source  12 , such as one or more retardant canisters containing an extinguishing gas  22  such as Halon or another extinguishing gas, is in fluid communication, for example through one or more primary conduits  14  and secondary conduits  16 ,  19  with both a cargo deck  18  retardant dispersal system and a main deck  20  retardant dispersal system. The retardant  22  is delivered from the retardant source  12  to the fire location using, for example, one or more primary release valves, diverters, or frangible disks  24 . Using a fire retardant source  12  in fluid communication with both the cargo deck  18  and the main deck  20  reduces weight by eliminating redundant retardant sources, for example a first retardant source for the cargo deck  18  and a second retardant source for the main deck  20 . 
     For illustration,  FIG. 2  depicts a plan view of a fire suppression system component  26  for the main deck  20 , which may be repeated for the cargo deck  18 . It will be understood that the embodiments depicted in each of the FIGS. are generalized schematic illustrations and that other components may added or existing components may be removed or modified. In operation, one or more sensors  28 , such as a smoke detector, heat detector, or flame detector (ultraviolet, infrared, near-infrared, etc.), continually monitors for smoke and/or fire on the main deck  20 . The main deck  20  and the cargo deck  18  may include a plurality of portable cargo or shipping containers  30  (boxes, pallets, cargo container, etc.) for storing cargo during transport. For illustration purposes only, the shipping containers  30  are arranged in an array of three rows, A, B, C, and 10 columns  1 - 10 . In this embodiment, at least one sensor  28  directly overlies each shipping container  30 . 
     Upon sensing a fire event at a sensor location on the main deck  20 , the primary release valve  24  is configured, for example by a controller  32 , into a release position such that retardant  22  is released from the retardant source  12  and directed to the main deck  20  through conduit  19 . The controller  32  may be, for example, a computer device in wired or wireless communication with the primary release valve  24  as well as with the other various components as described herein, and may include a processor, such as a microprocessor, memory, logic devices, etc., not individually depicted for simplicity. The controller  32  may be part of a larger freighter computer network that coordinates emergency signals, for example a system that is integrated into aircraft electronics. In another embodiment, the controller  32  may be part of a stand-alone fire detection and suppression system  10 , and may include an alarm on a cockpit panel that receives a wireless signal from the controller for enunciating an alarm condition. 
     Upon detection of the fire event, the controller  32  positions one or more of a series of secondary release valves  34  so that retardant  22  is precisely directed to the fire event. In an embodiment, each sensor  28  may be paired one-to-one (i.e., uniquely paired) with one secondary release valve  34  so that the fire suppression system  10  more accurately delivers retardant  22  to the detected location of the fire event. For example, if sensor  28  at Row C, Column  1  (i.e., location “ 1 C”) detects smoke or fire, the primary release valve  24  and the secondary release valve  34  at  1 C are opened and all other secondary release valves remain closed so that retardant  22  is directed to location  1 C. In this embodiment, retardant is ejected from only the one or more nozzles paired with the sensor detecting the fire. This is in contrast to some prior systems that flood an entire open space with retardant through all nozzles, which often requires a large volume and weight of retardant. Thus in an embodiment of the present teachings, the amount of retardant  22  required is reduced, as is the weight of the required stored retardant, compared to some prior fire suppression systems, as the system more precisely delivers the retardant  22  to the needed location. Decreasing fire suppression system weight reduces flight costs, for example fuel costs. 
       FIG. 3A  is a cross section along  3 - 3  of  FIG. 2  during release of retardant  22  at location  1 C. As discussed above, in an embodiment, each sensor  28  may be uniquely paired with one secondary release valve  34  as depicted in  FIG. 3  so that the fire suppression system  10  more accurately delivers retardant  22  to the detected location of the fire event. Additionally, each sensor  28  and each secondary release valve  34  may be uniquely paired with one (or more) retardant delivery nozzle  36  that directs retardant  22  onto the precise location of the fire event. In an embodiment, the components of  FIG. 3A , except for containers  30 , are installed as a fixed part of the aircraft. The permanent components may be designed for an anticipated arrangement of containers  30 , which may be used to transport cargo into and out of the aircraft. 
     Other arrangements of nozzles and detectors are also contemplated. For example,  FIG. 3B  depicts a cross section of an alternate embodiment having two or more retardant delivery nozzles  36  that direct retardant  22  onto the precise location of the fire event, for example onto one container  30 . In the  FIG. 3B  embodiment, secondary release valve  34 A may be positioned in the  FIG. 4A  configuration (described below) and secondary release valves  34 B may be positioned in the  FIG. 4B  configuration to deliver retardant to the precise location of the fire event. It will be understood that the various embodiments are not limited to the number or position of the nozzles  36 , containers  30 , valves  24 ,  34 , detectors  28 , or rows/columns except where specified. 
     In another embodiment, if a fire event is detected at location  1 C, other secondary release valves  34  adjacent to  1 C may be opened to ensure sufficient fire control, such as locations  1 B,  2 B, and  2 C. While delivering retardant to more than one location increases an amount of required retardant, the efficiency is improved compared to some prior systems that flood an entire open space with retardant during a fire event. Thus system weight may be reduced. 
     Various secondary release valve  34  configurations are contemplated. For example, two position electromechanical valves may be used, depending on a configuration of tertiary conduits  38 A- 38 C, where the valve position is either ON or OFF so that retardant is either released or not released from a particular nozzle  36 . In another configuration, three position electromechanical ball valves or diverters may be used, such as the electromechanical ball valve  40  depicted in  FIGS. 4A-4C  spaced along each of the conduits  38 A- 38 C. These valves allow L-port and T-port flow paths, and may include a housing  42  that surrounds and seals an electrically-rotatable ball  44  within. In the position depicted in  FIG. 4A , the secondary release valve  40  blocks retardant  22  from passing through either the nozzle  36  or to other downstream secondary release valves. In the position depicted in  FIG. 4B , the secondary release valve  40  permits passthrough of retardant  22  to other downstream secondary release valves  40  (which may be open or closed), but blocks retardant  22  from exiting its paired nozzle  36 . In the position depicted in  FIG. 4C , the secondary release valve  40  allows passthrough of retardant to other downstream secondary release valves  40 , and allows retardant  22  to flow through its paired nozzle  36 . The proper position of each secondary release valve  40  is determined by controller  32  software and/or firmware based on the location of the fire event. The position is set by the controller  32 , which may output a signal to a motor (i.e., electric actuator, not individually depicted for simplicity) associated with each ball valve  40 . The dimensions and orientation of a passthrough channel  46  and a nozzle channel  48  within the ball  44  may be sized and configured to supply a desired amount of retardant  22  through the passthrough channel  46  and the nozzle channel  48 . While  FIG. 4  depicts the nozzle channel  48  intersecting the passthrough channel at an angle of 90°, other angles may be used to deliver a proper and predetermined amount of retardant  22  to the nozzle  36  when the valve is in the  FIG. 4C  position. 
     The conduits for transporting the retardant  22  from the retardant source  12  to the decks  18 ,  20  may include various configurations. For example, a primary conduit  14  transports fire retardant  22  from the retardant source  12  to the primary valve  24 . A first deck (i.e., cargo deck) conduit  16  transports retardant  22  from the primary valve  24  to the secondary release valves  34  on the first deck, and a second deck (i.e., main deck) conduit  19  transports retardant  22  from the primary valve  24  to the secondary release valves  34  on the second deck. Tertiary conduits  38 A- 38 C ( FIG. 2 ) on each of the decks  18 ,  20  transport retardant  22  between the plurality of secondary release valves on each respective deck  18 ,  20 . 
     In another aspect of the present teachings, depicted in the perspective depiction of  FIG. 5 , the cargo containers  30  in proximity to one or more of the sensors  28  may be configured so that heat, smoke, or other fire-indicative gasses  50  are allowed to more quickly escape a cargo container  30  for detection by a sensor  28 . In the  FIG. 5  embodiment, each cargo container  30  includes one or more apertures  52  for the passage of the fire indicator  50 . Apertures  52  may be placed on one or more sides and/or the top of the container. While the apertures  52  may adversely provide increased oxygen to the inside of the container  30 , a decrease in time from initial fire activity to fire detection may be useful in some implementations. 
       FIG. 6  is a schematic depiction of a heat sensor  60  that may be used on or within each container  30  in an embodiment of the present teachings. Heat sensor  60  may be used in place of, or in conjunction with, another sensor such as sensor  28  ( FIG. 2 ). In this embodiment, an electrically conductive solid material  62  is located within a hollow tube  64  or other hollow container. The composition of the solid material  62  is selected such that it remains a solid at ambient temperatures and melts or flows at a temperature encountered during a fire. The solid material  62  may be, for example, lead, a lead alloy, or another suitable material. The material that forms the tube  64  is selected such that it remains a solid during high temperatures for a time sufficient to enable notification of a fire event. The heat sensor  60  may further include a first electrode  66  at a first end of the tube  64  and a second electrode  68  at a second, opposite end of the tube  64 . One or both electrodes  66 ,  68  may be separated from the electrically conductive solid material  62  by a gap or space  67  within the tube  64  as depicted, such that the two electrodes  66 ,  68  remain electrically isolated from each other during normal operation. Each electrode  66 ,  68  is separately electrically coupled, for example with a trace or wire  69 , to detector electronics that may include a battery  70  and a wireless transmitter  72  that may be powered by the battery  70 . In an embodiment, the solid material  62 , tube  64 , and electrodes  66 ,  68  may be located within the container  30 , while the transmitter  72  is located on an external surface of the container  30 . In another embodiment, the entire heat sensor  60  may reside within the container  30 . In another embodiment, the entire heat sensor  60  may reside outside of the container  30  such as on an external surface of the container  30 . 
     During normal operation, the electrodes  66 ,  68  remain electrically isolated from each other such that the heat sensor  60  remains unpowered and inactive to preserve battery life. In another embodiment, the heat sensor  60  may be powered during normal operation, for example to output a signal to specify normal operation or to output results of a self test. 
     During a fire event, heat from the fire melts the solid material  62  within the tube  64  such that it becomes an electrically conductive liquid material  74  within the tube  64 . The electrically conductive liquid material  74  electrically shorts the first  66  and second  68  electrodes together, which completes an electric circuit and causes activation of the wireless transmitter  72 . The powered wireless transmitter  72  may output one or more signals and/or data streams to the controller  32 . In an embodiment, the signal output by the wireless transmitter  72  may include data that notifies the controller  32  of the precise location of the heat sensor  60  and thus the precise location of the fire event. In another embodiment, the controller  32  may determine the location of the wireless transmitter  72 , for example, through triangulation using sensors (not individually depicted for simplicity) within the cargo deck  18  and/or main deck  20 . Thus heat sensor  60  may provide a reliable, low-cost technique for identifying the precise location of a fire event, as it relies on heat to sense the fire location rather than, for example, smoke which is more susceptible to being channeled away from the fire location by air currents. 
     The controller  32  may be in wired and/or wireless communication with one or more of the primary release valve  24  and the plurality of secondary release valves  34 , as well as with other fire suppression system components and aircraft electronics. The primary release valve  24  and secondary release valves may be electromechanical valves such that the controller can control a position of each valve. Further, the controller  32  may be in wired and/or wireless communication with one or more of the plurality of sensors  28 , such that the sensors  28  monitor a fire status over the sensor proximity and provide a fire status to the controller  32 . 
     Some prior systems, such as systems using high rate discharge (HRD), output a large volume of retardant through all nozzles in a short time in an attempt to flood an entire open space to control a fire event, and thus use a large volume of gas over a short duration. HRD systems may subsequently use a secondary low rate discharge (LRD) system through all nozzles in an attempt to control any remaining fire for a duration of time that allows the aircraft to safely land. In an aspect of the present teachings, it is realized that oxygen supply in the cargo areas (for example, cargo deck  18  and main deck  20 ) may be less at higher altitudes. If a fire starts at higher altitudes, the lower oxygen supply may retard the growth of the fire such that it smolders until the aircraft descends to lower altitudes having increased oxygen. Because of the precise deployment of retardant to the fire event with the present teachings, a smaller retardant supply will allow for continuous retardant dispersal at the fire location during descent of the aircraft. Thus, in an embodiment, retardant is continuously dispensed at the precise location of the fire event beginning a time during descent, when descent begins, or from the time the fire event is identified. Once ejection of the extinguishing gas from the nozzle(s) is initiated, ejection may be continuous, for example, up until the time after the aircraft lands and is safely on the ground. 
     As retardant is ejected from less than all the nozzles on the deck on which fire is detected, for example from only the one or more nozzles paired with the sensor detecting the fire, the retardant supply is used sparingly at a low rate which allows retardant deployment for an extended period of time. If the fire continues to spread and is subsequently detected by other sensors, retardant can begin to be ejected from other nozzles paired with the other detecting sensors. 
     Thus an embodiment of the present teachings may include one or more elements. For example, one or more retardant nozzles may be uniquely paired with, and located in proximity to, a single fire event sensor (detector) of a plurality of fire sensors. Further, a plurality of secondary release valves may each be uniquely paired with one of a plurality of fire event sensors, and with one of a plurality of retardant nozzles. Uniquely pairing each secondary release valve with one sensor and with one nozzle places the release valve and nozzle in close proximity to the detector. With this arrangement of elements the fire is more quickly detected and the retardant is more precisely dispensed at the fire than with some prior systems. 
     It will be realized that, in other embodiments, two or more valves and nozzles may be paired with a single detector to cover a larger area with fewer components, for example to decrease costs, with the two or more valves and nozzles simultaneously delivering retardant. This may require more retardant than a system where each detector is uniquely paired with one secondary release valve, and may increase overall weight of the fire suppression system. 
     The close proximity of the nozzle to the sensor delivers retardant more precisely to the fire event location. The fire may then be more quickly controlled which requires a lesser amount of retardant than with some prior systems, which decreases the overall weight of the fire suppression system and flight costs. 
     In another embodiment, a fire suppression system in accordance with the present teachings may include one or more apertures through a surface of each cargo container so that heat, smoke, or other fire-indicative gasses are released from the cargo container more quickly before the fire has time to grow excessively. Detection will provide an action for the decompression of the cargo hold. No fire suppression action is required until the aircraft begins its descent. Activating the fire suppression system will provide fire protection during descent and minimize the quantity of extinguishing gas required to sustain concentration until aircraft has landed, thereby decreasing overall fire suppression system weight. 
     In an embodiment of the present teachings, a fire is more quickly detected than in prior systems, for example because of a higher density of sensors  28  across a cargo space  18 ,  20 . An increased number of sensors  28  improves the likelihood (probability) that a sensor  28  is nearer to the origin of the fire, and thus the fire is more quickly detected. More rapid fire detection results in a more rapid initiation of emergency procedures while the fire is smaller, thus requiring a smaller on-board extinguishing gas supply and less weight. 
     Once the fire is detected, an embodiment of the present teachings may further include the use of an optional decompression of the cargo area. Decompression opens the relatively higher pressure cargo area to the relatively lower pressure atmosphere, thus venting oxygen to the atmosphere, decreasing the oxygen supply to the fire, and slowing the growth of the fire. This is particularly useful at low-oxygen altitudes, for example above about 25,000 feet. Decompression may be performed automatically at higher altitudes, for example at 25,000 feet or above, using a valve (not individually depicted for simplicity) that may be controlled using a wired or wireless signal output by the controller  32 . One or more decompression valves used to decompress a cargo space of an aircraft are known in the art. Upon detection of a fire by a sensor  28 , the controller  32  may send a wired or wireless signal to move the valve from a closed position to an open position to expose the deck to the atmosphere and to decompress the deck  18 ,  20  where the fire has been detected. 
     After decompression, an optional initial HRD which floods the cargo area with an extinguishing gas  22  ejected from some or all of nozzles  36  may be performed. Because of early fire detection and/or decompression, fire intensity and/or growth is retarded, particularly at higher altitudes, and the HRD may be delayed until the initiation of aircraft descent. Decompression further allows the descent and landing of the aircraft to be delayed if required, for example if the aircraft is over a large body of water. An HRD deployment alone may sufficiently retard or extinguish the fire such that subsequent extinguishing gas deployment is not at all required. In other embodiments, an optional extended LRD deployment of extinguishing gas  22  through one or more nozzles  36 , but less than all nozzles  36 , may be performed. The nozzle(s) through which extinguishing gas is deployed may be based on the location of the sensor that first detects the fire. An LRD deployment through less than all of the nozzles  36  decreases the rate of retardant use compared to systems that deploy retardant through all nozzles. Thus a smaller on-board emergency extinguishing gas supply (and a lower weight) is required. The LRD may be continued until after the aircraft has landed safely which, at maximum altitude, is expected to be 20 minutes or less under emergency conditions. 
     Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the present teachings are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any and all sub-ranges subsumed therein. For example, a range of “less than 10” can include any and all sub-ranges between (and including) the minimum value of zero and the maximum value of 10, that is, any and all sub-ranges having a minimum value of equal to or greater than zero and a maximum value of equal to or less than 10, e.g., 1 to 5. In certain cases, the numerical values as stated for the parameter can take on negative values. In this case, the example value of range stated as “less than 10” can assume negative values, e.g. −1, −2, −3, −10, −20, −30, etc. 
     While the present teachings have been illustrated with respect to one or more implementations, alterations and/or modifications can be made to the illustrated examples without departing from the spirit and scope of the appended claims. For example, it will be appreciated that while a process may be described as a series of acts or events, the present teachings are not limited by the ordering of such acts or events. Some acts may occur in different orders and/or concurrently with other acts or events apart from those described herein. Also, not all process stages may be required to implement a methodology in accordance with one or more aspects or embodiments of the present teachings. It will be appreciated that structural components and/or processing stages can be added or existing structural components and/or processing stages can be removed or modified. Further, one or more of the acts depicted herein may be carried out in one or more separate acts and/or phases. Furthermore, to the extent that the terms “including,” “includes,” “having,” “has,” “with,” or variants thereof are used in either the detailed description and the claims, such terms are intended to be inclusive in a manner similar to the term “comprising.” The term “at least one of” is used to mean one or more of the listed items can be selected. Further, in the discussion and claims herein, the term “on” used with respect to two materials, one “on” the other, means at least some contact between the materials, while “over” means the materials are in proximity, but possibly with one or more additional intervening materials such that contact is possible but not required. Neither “on” nor “over” implies any directionality as used herein. The term “about” indicates that the value listed may be somewhat altered, as long as the alteration does not result in nonconformance of the process or structure to the illustrated embodiment. Finally, “exemplary” indicates the description is used as an example, rather than implying that it is an ideal. Other embodiments of the present teachings will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the present teachings being indicated by the following claims. 
     Terms of relative position as used in this application are defined based on a plane parallel to the conventional plane or working surface of a workpiece, regardless of the orientation of the workpiece. The term “horizontal” or “lateral” as used in this application is defined as a plane parallel to the conventional plane or working surface of a workpiece, regardless of the orientation of the workpiece. The term “vertical” refers to a direction perpendicular to the horizontal. Terms such as “on,” “side” (as in “sidewall”), “higher,” “lower,” “over,” “top,” and “under” are defined with respect to the conventional plane or working surface being on the top surface of the workpiece, regardless of the orientation of the workpiece.