Patent Publication Number: US-2022233898-A1

Title: Fire Extinguishing Discharge Nozzle for Helicopter Engine Compartment

Description:
BACKGROUND 
     Aircraft include many systems that facilitate operation and safety of the aircraft. For example, engines provide power, either directly or indirectly, to other systems such as rotor systems, gear boxes, flight control systems, interior environmental control systems, and the like. Such systems include liquids, such as fuel and lubricants, to facilitate operations. For example, fuel is burned to power components and lubricants are employed to reduce wear on components and to transfer heat away from components. These flammable liquids can sometimes escape from their respective systems, which increases the risk of fire in an aircraft engine compartment. Aircraft typically have an onboard system designed to extinguish fires, such as fire bottles located in the fuselage with tubing that brings a fire extinguishing agent into the engine compartment where the agent is disbursed by discharge nozzles. The fire bottles are typically electrically operated after manual selection by the flight crew based upon automatic fire detection. 
     SUMMARY 
     Embodiments are directed to systems and methods for providing a fire extinguishing system having nozzles for distributing a fire extinguishing agent, wherein the nozzles are oriented to prevent accumulation of water, rain, humidity, or other liquids and foreign object debris/damage (FOD). 
     In one example embodiment, a rotorcraft comprises an airframe having an engine compartment, an engine disposed within the engine compartment, a fire bottle configured to hold a fire extinguishing agent, at least one agent tube coupled to the fire bottle and configured to carry the fire extinguishing agent to the engine compartment, and a nozzle on the at least one agent tube, the nozzle positioned above the engine and oriented in a downward-facing direction. The nozzle has at least one opening and is configured to allow liquid or other FOD to drain out of the at least one opening instead of allowing the liquid or other FOD to flow into the at least one agent tube. The nozzle may have a chamfer opening that faces downward. The agent tubes may comprise an inverted trap section that is configured to allow liquid or other FOD to drain out of the at least one agent tube instead collecting in the at least one agent tube. 
     The rotorcraft may further comprise at least one vertical firewall enclosing the engine compartment, wherein the at least one agent tube penetrates the at least one vertical firewall. The fire bottle may be located above the engine. 
     The rotorcraft may further comprise an engine deck below the engine, wherein the at least one agent tube penetrates the engine deck, and wherein the at least one agent tube extends vertically upward to the nozzle, which is oriented facing down above most or all of the engine. The fire bottle may be located below the engine deck. 
     In another example embodiment, a rotorcraft comprises an airframe having an engine compartment, an engine disposed within the engine compartment, a fire bottle configured to hold a fire extinguishing agent, at least one agent tube coupled to the fire bottle and configured to carry the fire extinguishing agent to the engine compartment, and a nozzle on the at least one agent tube, the nozzle positioned below the engine and oriented in an upward-facing direction, wherein the nozzle is configured to prevent liquid from flowing into the at least one agent tube by a cover, valve, or membrane as discussed below. 
     The nozzle may comprise a hinged cover. The hinged cover may be held in a closed position by a spring. The spring may be configured to assert a force that is overcome by pressure generated by a fire extinguishing agent released from the fire bottle. 
     The nozzle may comprise a spring-loaded flapper valve. 
     The nozzle may comprise a discharge port, and a membrane configured to fit over the discharge port. The membrane may be configured to rupture or release when exposed to pressure generated by a fire extinguishing agent released from the fire bottle. 
     The nozzle may comprise a discharge port, and a cap configured to fit over the discharge port. The cap may be configured to expose the discharge port when subject to pressure generated by a fire extinguishing agent released from the fire bottle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein: 
         FIG. 1  shows an aircraft adapted for user with embodiments of the present application. 
         FIG. 2  is a view of an engine compartment of a rotorcraft illustrating one embodiment of the fire extinguishing system. 
         FIG. 3  depicts a prior art engine compartment for an aircraft, such as a rotorcraft. 
         FIG. 4  depicts an engine compartment of an aircraft illustrating an alternative embodiment of a fire extinguishing discharge system. 
         FIG. 5  depicts an alternative fire extinguishing discharge nozzle configuration having a chamfer nozzle. 
         FIG. 6  depicts an alternative fire extinguishing discharge nozzle configuration having a trap nozzle. 
         FIG. 7  depicts an alternative fire extinguishing discharge nozzle configuration having a capped nozzle. 
     
    
    
     While the system of the present application is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the system to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present application as defined by the appended claims. 
     DETAILED DESCRIPTION 
     Illustrative embodiments of the system of the present application are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer&#39;s specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. 
     In the specification, reference may be made to the spatial relationships between various components and to the spatial orientation of various aspects of components as the devices are depicted in the attached drawings. However, as will be recognized by those skilled in the art after a complete reading of the present application, the devices, members, apparatuses, etc. described herein may be positioned in any desired orientation. Thus, the use of terms such as “above,” “below,” “upper,” “lower,” or other like terms to describe a spatial relationship between various components or to describe the spatial orientation of aspects of such components should be understood to describe a relative relationship between the components or a spatial orientation of aspects of such components, respectively, as the device described herein may be oriented in any desired direction. 
       FIG. 1  shows an aircraft  100  in accordance with embodiments of the present application. In the exemplary embodiment, aircraft  100  is a helicopter having a fuselage  101  with an airframe (not shown) and a rotor system  102  coupled to the airframe. A plurality of rotor blades  103  is operably associated with a rotor system  102  for creating flight. The pitch of each rotor blade  103  can be managed or adjusted to selectively control direction, thrust, and lift of the aircraft  100 . 
     A tail boom  104  is depicted that further includes tail rotor and anti-torque system  105 . The tail structure  104  may be used as a horizontal stabilizer. Aircraft  100  further includes a rotor mast  106 , which connects the main rotor  102  to a main rotor gearbox  107 . The main rotor gearbox  107  is connected to one or more accessory gear boxes  108  and one or more reduction gearboxes  109   a ,  109   b . Each reduction gearbox  109   a ,  109   b  is connected to one or more engines  110   a ,  110   b , which are within an engine compartment  111 . A tail rotor drive shaft  112  is connected to the main rotor gearbox  107  and transmits mechanical rotation to the tail rotor gear box  113  via tail rotor drive shaft  114  and intermediate gear box  115 . 
     Engines  110   a ,  110   b  are the primary source of power for aircraft  100 . Torque is supplied to the rotor system  102  and the anti-torque system  105  using engines  110   a  and  110   b . One or both of the engines  110   a ,  110   b  may leak or otherwise expel liquids into the compartment  111 . Such liquids are often flammable and may include, for example, petroleum-based fuel, coolant, heat-transfer fluid, hydraulic fluid, and/or a lubricant. Fire suppression in aircraft  100  may use both passive and active systems to reduce and eliminate fires. Passive methods include, for example, the use of noncombustible materials, separation by firewalls, compartmentalization, isolation, ventilation and cooling, and proper drainage. Active methods include fire detection and extinguishing systems. One or more engine fire bottles  116  and associated engine fire extinguishing tubing  117  are mounted inside fuselage  101  and below engine compartment  111 . Engine fire bottles  116  contain a fire extinguishing agent, such hydrofluorocompounds (HFCs), that may be released into engine compartment  111  upon activation by a pilot. 
     It should be appreciated that the aircraft  100  of  FIG. 1  is merely illustrative of a variety of aircraft that can be used to implement embodiments of the present disclosure. Other aircraft implementations can include, for example, tiltrotors, fixed wing airplanes, hybrid aircraft, unmanned aircraft, gyrocopters, a variety of helicopter configurations, and drones, among other examples. Moreover, it should be appreciated that even though aircraft are particularly well suited to implement embodiments of the present disclosure, the described embodiments can also be implemented using non-aircraft vehicles and devices. 
       FIG. 2  is a view of the engine compartment  111  of aircraft  100  illustrating reduction gearbox  109   a  and engine  110   a . Engine compartment  111  is depicted as partially open, such as by removing maintenance or access panels on fuselage  101 . A firewall  201  separates engine  110   b  from engine  110   a . Firewall  201  provides passive fire suppression by isolating the engines  110   a ,  110   b  from each other so that a fire involving one engine does not spread to the other engine. Firewall  201  may be formed using titanium or other appropriate flameproof bulkhead material that separates the engine compartment from the rest of aircraft  100 . Firewall  201  prevents any hazardous quantity of liquid, gas, or flame from passing through the firewall to other parts of aircraft  100 . 
     In addition to passive fire protection, engine  110   a  also has an active fire extinguishing system comprising extinguishing agent tubes  202 ,  203  that are coupled to fire bottle  204  below engine deck  205 . Agent tubes  202 ,  203  rise from engine deck  205  along and around opposite sides of engine  110   a . Agent tubes  202 ,  203  terminate in nozzles  206 ,  207 , which are positioned above engine  110   a  and configured to maximize distribution of fire extinguishing agent in the event of an engine fire. Nozzles  206  and  207  are generally downward facing so that water and other fluids that drip or splash on tubes  202  and  203  do not get captured by nozzles  206  and  207 . 
     Although  FIG. 2  illustrates agent tubes  202 ,  203  as located within engine compartment  111 , it will be understood that, in other embodiments, the agent tubes may be routed outside engine compartment  111  between fire bottle  204  and a point above engine  110   a . The agent tubes  202 ,  203  and/or nozzles  206 ,  207  may enter the engine compartment  111  through a vertical firewall, for example. In other embodiments, the fire bottle  204  may be located within engine compartment  111 . 
     The deployment of agent tubes  202 ,  203  and nozzles  206 ,  207  above engine  110   a  is an improvement over prior fire suppression systems. Traditionally, engine fire extinguishing discharge nozzles for a helicopter are positioned below the engine and direct agent upwards to fill compartment. The orientation of prior designs is prone to accumulating moisture and FOD in the agent tubes due to water from engine wash, rain, and humidity. As a result, prior fire suppression systems were at risk of fire bottle failures, for example, due to corrosion resulting from wash fluid entering the tubes and back flowing to bottle. Extinguishing agent nozzles that are positioned below the engine are also susceptible to water and soap residue entering the agent tubes, which will corrode the agent tubes and fire bottles. By re-orienting the extinguishing agent nozzles, this can prevent accumulation of water, rain, humidity, and other FOD that could compromise the fire extinguishing system. 
       FIG. 3  depicts a prior art engine compartment  300  for an aircraft, such as a rotorcraft. Fire bottles (not shown) are located below engine deck  301 . Agent tubes  302  and  303  extend from the fire bottles through deck  301  and terminate a short distance above deck  301 . Nozzles  304 ,  305  face upwards and are directed toward an engine (not shown) in compartment  300 . Water and soap may enter compartment  300  through cooling ducts or other gaps. For example, Liquid may enter when the aircraft is subjected to rainy weather conditions and/or pressurized water, such as while washing the engine or fuselage. Other fluids, such as fuel and oil, may also be present in compartment  300  due to leaks and maintenance. Liquid drainage systems will catch some of the water and other liquids and will carry them to locations outside compartment  300 . However, upward-facing nozzles  304 ,  305  will also catch some of the liquids, which will then enter agent tubes  302  and  303 . These liquids may then cause blockages and corrosion, which can impair the operation and reduce efficacy of the aircraft&#39;s fire suppression system. 
       FIG. 4  depicts an alternative fire extinguishing discharge nozzle configuration for a helicopter engine compartment. One or more fire bottles  401  are located above and/or behind engine compartment  111 . Agent tubing  402  extends from fire bottle  401  and branches into agent tubes  403 ,  404 , which enter compartment  111  above engine  110   a  and extend along opposite sides of engine  110   a . Agent tubes  403 ,  404  end in downward-facing nozzles that minimize capture of water or other liquids that are sprayed, splashed, or dripped within compartment  111 . 
     The configuration illustrated in  FIG. 4  also minimizes the length of agent tubes  403  and  404  compared to the configuration shown in  FIG. 2 . The use of shorter agent tubes incurs a lower cost for the fire suppression system. The shorter agent tubes may also provide a higher pressure at the nozzles  405  and  406  compared to systems with longer agent tubes. Agent tubes  403  and  404  are approximately in plane with fire bottle  401 , which also limits pressure drop along the agent tubes. 
     In other embodiments, nozzles  405  and  406  are positioned below fire bottle  401 , which gives the agent lines  403 ,  404  a downward slope relative to the fire bottle  401 . The downward slope will cause any water that does enter nozzles  405 ,  406  to drain back out of the agent tubes  403 ,  404  over time. This slope away from bottle  401  ensures that water does not collect in agent tubes  403  and  404  or at fire bottle  401 , which minimizes corrosion, blockages, and other damage. 
     The embodiment illustrated in  FIG. 4  provides several advantages over prior aircraft fire extinguishing systems. By reducing the opportunity for water and other liquid entering the agent tube, the embodiments disclosed herein eliminate the risk of clogging agent tubes thereby degrading the performance of the fire extinguishing system due to fluid in the agent tubes. The embodiments disclosed herein also eliminate the risk of corrosion on the squib cartridge at the fire bottle. Such corrosion could cause the squib to not fire or improperly fire thereby rendering the fire bottle inoperative. The improvements to the fire extinguishing system also eliminate maintenance inspections required to check and clear the agent tubes after an engine wash or rain. 
       FIG. 5  depicts an engine compartment  500  of an aircraft illustrating an alternative embodiment of a fire extinguishing discharge system. Engine  501  is located in compartment  500 . An aft engine firewall  502  separates engine compartment  500  from engine exhaust  503 , and a forward engine firewall  504  provides a barrier between engine  501  and reduction gearbox  505 . Engine deck  506  separates the engine compartment  500  from the aircraft cabin. Firewall  507  separates engine  501  from a second engine compartment. A fire suppression system  508  provides fire protection to engine  501 . Fire bottle  509  holds a fire extinguishing agent that can be released upon pilot command to flow through agent tube  510 . The agent tube  510  penetrates through aft firewall  502  and ends in a nozzle  511 . The nozzle  511  is configured to disburse the extinguishing agent inside compartment  500  and onto engine  501 . 
     Nozzle  511  has a chamfer end  512  that is cut so that fire extinguishing agent is directed downward toward engine  501 . Water, liquids, and FOD that fall on nozzle  511  is prevented from entering opening  513  due to the downward orientation of the opening  513  on the chamfer end  512 . As result, water, liquid, and FOD do not enter agent tube  510  and do not flow back to fire bottle  509 , which prevents corrosion and other damage to fire suppression system  508 . 
       FIG. 6  depicts an engine compartment  500  as illustrated in  FIG. 5  with an alternative embodiment of a nozzle for a fire extinguishing system. Similar elements in  FIG. 6  are labeled the same as  FIG. 5 . Fire suppression system  601  provides fire protection to engine  501 . Fire bottle  602  holds a fire extinguishing agent that can be released upon pilot command to flow through agent tube  603  to compartment  500 . The agent tube  603  penetrates through aft firewall  502  as agent tube  604 , which ends in a downward-facing nozzle  605 . Agent tube  604  has an inverted trap section  606 . In typical plumping, a P-trap is used to hold water in order to prevent the flow of gas, such as sewer gas, through a pipe. Inverted trap  606  has the opposite effect in that it is intended to not hold water. If water enters nozzle  605 , it will not enter agent tube  604  because inverted trap  606  will cause the water to drain back out through nozzle  605 . The water (or other liquid or FOD) will move vertically up tube section  607  and then gravity will pull the water straight back down and out of nozzle  605 . 
     Although fire bottles  509  and  602  are shown as being on approximately the same level as nozzles  511  and  605 , respectively, it will be understood that in other embodiments the fire bottle may be located above or below the discharge nozzle. Agent tubing  510 ,  603  may be routed as appropriate to connect fire bottles  509  and  602  to nozzles  511  and  605 . For example, in other embodiments, the fire bottle may be located below engine deck  506  and the agent tubing may penetrate deck  506  and extend upward to position the nozzle  511  or  605  above engine  501 . 
       FIG. 7  depicts another alternative embodiment of a nozzle for a fire extinguishing system. Similar elements in  FIG. 7  are labeled the same as  FIG. 5 . Fire suppression system  701  provides fire protection to engine  501 . Fire bottle  702  holds a fire extinguishing agent that can be released upon pilot command to flow through agent tube  703  to compartment  500 . The agent tube  703  penetrates through deck  506  as agent tube  704 , which ends in an upward-facing nozzle or discharge port  705 . A cap  706  covers and protects nozzle  705  and agent tubes  704 ,  703 . Water or other liquid or other FOD in compartment  500  are blocked from entering agent tubes by cap  706 . Under normal operating conditions, cap  706  may be held in the closed position by a spring-loaded hinge  707 . When the fire extinguishing agent needs to be deployed, it is released from fire bottle  702  into agent tubes  703 ,  704 . The fire extinguishing agent will build pressure in agent tube  704 , which then pushes cap  706  out of the way so that nozzle  705  is exposed and the fire extinguishing agent can flow freely into compartment  500 . 
     In other embodiments, nozzle  705  and agent tubes  704 ,  703  may be protected by a closure that is held in a closed position by a mechanical device. The mechanical device is configured to assert a closing force that may be overcome by pressure generated by a fire extinguishing agent that is released from a fire bottle. The closure may be a hinged cover that is held in the closed position by a spring, a spring-loaded flapper valve, a spring-loaded check valve, or any other mechanically activated valve that is spring loaded whereby valve opens when pressure/force exceeds a certain specified threshold. 
     Alternatively, cap  706  may be connected to agent tube  704  by a tether or cable  708  so that cap  706  is blown off of agent tube  704  when the fire extinguishing agent is deployed. The tether or cable  708  keeps cap  706  attached to agent tube  704  so that cap  706  does not become FOD and tumble loosely in engine compartment  500 . 
     In a further embodiment, spring-loaded cap  706  may be replaced with a disposable rupture membrane over the discharge port  705 . The membrane may be thin stainless steel, for example, that would prevent water, liquid, and FOD from entering agent tube  704 . The thin membrane will rupture easily on discharge of fire bottle  702  due to the pressure of the fire extinguishing agent in tube  704 . 
     The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized that such equivalent constructions do not depart from the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention.