Patent Description:
The present disclosure relates to aircraft evacuation assemblies for aircraft, and, more specifically, to release systems for evacuation slides.

An evacuation slide assembly may include an inflatable slide that helps passengers disembark from an aircraft in the event of an emergency or other evacuation event. Conventionally, deployment of the inflatable slide generally includes multiple release assemblies configured to facilitate the release of the inflatable slide from its stored position on the aircraft. For example, inflatable slides may be generally stored within a soft cover that is disposed within a container, such as a packboard. <CIT> describes a valve for an aircraft inflation system. <CIT> describes a shape memory alloy actuator. <CIT> describes an adjustable release lanyard.

A release system for an evacuation slide assembly of an aircraft is disclosed herein. The release system includes a blowout panel and a first actuator comprising a first housing, a first shape memory alloy spring, a first compression spring, and a first spindle. The first shape memory alloy spring is configured to bias the first spindle to retract into the first housing in response to being electrically energized to deploy the blowout panel.

In various embodiments, the release system further comprises a power source, wherein the first shape memory alloy spring is configured to be electrically energized in response to an evacuation event.

In various embodiments, the release system further comprises a soft cover and a second actuator comprising a second housing, a second shape memory alloy spring, a second compression spring, and a second spindle. The second shape memory alloy spring may be configured to bias the second spindle to retract into the second housing in response to being electrically energized to deploy the soft cover.

In various embodiments, the release system further comprises a control unit, a first switch coupled between the power source and the first actuator, and a second switch coupled between the power source and the second actuator. The control unit may be configured to close the first switch and the second switch in response to the evacuation event to energize the first SMA spring and the second SMA spring.

In various embodiments, the first actuator is a ball lock, the first actuator further comprising a ball bearing, and the first shape memory alloy spring is configured to bias the first spindle away from the ball bearing in response to being electrically energized.

In various embodiments, the first actuator further comprises a frangible rod configured to extend through the first spindle.

In various embodiments, the first actuator further comprises a first nose fitting coupled to the first housing, wherein the first shape memory alloy spring is disposed in a first main chamber of the first housing, the first shape memory alloy spring is disposed between a first flange of the first spindle and the first nose fitting.

In various embodiments, in a locked state, the first actuator is configured to secure the blowout panel, and in response to being electrically energized, the first actuator is configured to transition to an unlocked state to release the blowout panel.

In various embodiments, in a locked state, the second actuator is configured to retain an evacuation slide enclosed within the soft cover, and in response to being electrically energized, the second actuator is configured to transition to an unlocked state to allow release of the evacuation slide from enclosure within the soft cover.

In various embodiments, the second actuator is configured to release a key-loop of a lacing to allow the lacing to unfurl.

An evacuation slide assembly for use with an aircraft is disclosed, in accordance with claim <NUM>.

In various embodiments, the evacuation slide assembly further comprises a packboard configured to be mounted to the aircraft, wherein the packboard comprises a packboard compartment.

In various embodiments, the evacuation slide is mounted to the packboard.

In various embodiments, the blowout panel extends across an opening of the packboard compartment, wherein the first actuator, in a first locked state, secures the blowout panel relative to the packboard to retain the evacuation slide within the packboard compartment.

In various embodiments, the soft cover is disposed within the packboard compartment and comprises lacing, wherein the second actuator, in a second locked state, retains the evacuation slide within the soft cover.

In various embodiments, the evacuation slide assembly further comprises a valve for controlling flow of the fluid from the charged tank.

In various embodiments, the first shape memory alloy spring surrounds the first spindle and abuts a flange of the first spindle.

A method of deploying an evacuation slide of an aircraft is disclosed, the method comprising flowing fluid from a fluid source to the evacuation slide, actuating a first actuator by flowing electrical current from a power source to a first shape memory alloy spring of the first actuator to release a blowout panel, and actuating a second actuator by flowing electrical current from the power source to a second shape memory alloy spring of the second actuator to release a soft cover.

In various embodiments, flowing the fluid from the fluid source to the evacuation slide, actuating the first actuator, and actuating the second actuator occur substantially simultaneously in response to an evacuation event.

In various embodiments, in response to flowing electrical current from the power source to the first shape memory alloy spring, the first shape memory alloy spring is configured to bias a first spindle to retract into a first housing.

A more complete understanding of the present disclosure, however, may best be obtained by referring to the detailed description and claims when considered in connection with the following illustrative figures. In the following figures, like reference numbers refer to similar elements and steps throughout the figures.

The detailed description of exemplary embodiments herein makes reference to the accompanying drawings, which show exemplary embodiments by way of illustration. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosures, it should be understood that other embodiments may be realized and that logical changes and adaptations in design and construction may be made in accordance with this disclosure and the teachings herein, insofar as they fall within the scope of the appended claims.

The scope of the disclosure is defined by the appended claims rather than by merely the examples described. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Also, any reference to tacked, attached, fixed, coupled, connected or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option. Surface shading lines may be used throughout the figures to denote different parts but not necessarily to denote the same or different materials.

As used herein, "aft" refers to the direction associated with the tail (e.g., the back end) of an aircraft, or generally, to the direction of exhaust of the gas turbine. As used herein, "forward" refers to the direction associated with the nose (e.g., the front end) of an aircraft, or generally, to the direction of flight or motion.

A release system for an evacuation slide of the present disclosure may include an electrically activated actuator comprising a SMA (shape memory alloy) spring. By providing an electrically activated actuator (as opposed to a pneumatically actuated actuator), additional pressurized gas is not used to operate the ball locks and actuator pin to release the cover (blowout) panel and soft cover. A release system of the present disclosure may reduce the weight and cost of the packboard assembly compared to existing designs as the number of components may be reduced. A release system of the present disclosure may be implemented in gas free/electrified inflation slide/raft deployment systems. A release system of the present disclosure may not utilize activate/de active keys to lock and unlock the ball lock assembly to open and close the cover (blowout) panel during maintenance. A release system of the present disclosure may be integrated with existing designs without impacting the frangible rod function. A release system of the present disclosure may avoid complicated regulator valve design as no pressurized gas is utilized to release the ball locks and actuator pin. By using electrically activated actuators, secondary operations related to ball lock and actuator pin gas delivery manifold tube routings on the packboard shell of various existing designs is not necessary.

Referring to <FIG>, an exemplary aircraft <NUM> is shown, in accordance with various embodiments. Aircraft <NUM> may comprise a fuselage <NUM> with wings <NUM> fixed to fuselage <NUM>. Emergency exit door <NUM> may be disposed on fuselage over wing <NUM> such that passengers exiting emergency exit door <NUM> would exit onto wing <NUM>. An evacuation slide assembly <NUM> may be disposed aft of emergency exit door <NUM>. Blowout panel <NUM> may cover evacuation slide assembly <NUM> when installed on the aircraft <NUM>. In various embodiments, the evacuation slide assembly <NUM> may include and/or be housed within a packboard mounted to the aircraft <NUM>.

The evacuation slide assembly <NUM> may jettison the blowout panel <NUM> and deploy an evacuation slide <NUM> (<FIG>), such as an inflatable slide, in response to emergency exit door <NUM> opening or in response to another evacuation event. The evacuation slide <NUM> may be packed within and otherwise stored and/or retained within a soft cover <NUM> (<FIG>). As described in greater detail below, the evacuation slide assembly <NUM> may include a release system <NUM> (<FIG>) that facilitates the deployment of the evacuation slide <NUM> and the release of both the blowout panel <NUM> and the soft cover <NUM>. In various embodiments, as described in greater detail below, the release system <NUM> may be actuated using a power source, such as an electrical power source. In various embodiments, actuation of the release system <NUM>, and thus deployment of the evacuation slide <NUM> and the deployment/release of both the blowout panel <NUM> and the soft cover <NUM>, may be electrically actuated.

With reference to <FIG>, the release system <NUM> of the evacuation slide assembly <NUM> is shown, as viewed from an inboard perspective, in accordance with various embodiments. The evacuation slide assembly <NUM> may include and/or may be housed within a packboard <NUM>. The release system <NUM> may include a fluid delivery manifold <NUM>. The fluid delivery manifold <NUM> may be capable of being fluidly coupled or fluidly coupled to a fluid source, such as a charged tank <NUM> of fluid. The charged tank <NUM> may be mounted to the back of the packboard <NUM>. In various embodiments, the charged tank <NUM> may contain a compressed fluid. For example, the charged tank <NUM> may be a pneumatic gas cylinder and flow of the compressed fluid from the charged tank <NUM> may actuate a portion of the release system <NUM>. In various embodiments, the fluid delivery manifold <NUM> may route fluid from the charged tank <NUM> to the evacuation slide to inflate the slide in response to an evacuation event. The charged tank <NUM> may provide pressurized gas to inflate the evacuation slide <NUM>.

The fluid delivery manifold <NUM> may include piping and/or tubes through which the fluid from charged tank <NUM> flows. The fluid delivery manifold <NUM> may include and/or be fluidly coupled to a valve <NUM>. The valve <NUM> may control flow of fluid from the charged tank <NUM> to the evacuation slide <NUM>, in accordance with various embodiments. In various embodiments, valve <NUM> may be, for example, electrically actuated in response to the emergency exit door <NUM> opening and/or in response to an evacuation event. However, it is contemplated herein that valve <NUM> may be actuated (i.e., opened) via any suitable method (e.g., mechanically actuated, pneumatically actuated, electrically actuated, etc.) in response to the emergency exit door <NUM> opening and/or in response to an evacuation event.

In various embodiments, the release system <NUM> further includes an actuator <NUM> (also referred to herein as a blowout panel actuator, an SMA spring-activated actuator, a ball lock, and/or a first actuator) and an actuator <NUM> (also referred to herein as a soft cover actuator, an SMA spring-activated actuator, an actuator pin, a piston actuator, and/or a second actuator). Blowout panel actuator <NUM> and/or soft cover actuator <NUM> may be electrically actuated. In various embodiments, the release system <NUM> further includes a power source <NUM>. The blowout panel actuator <NUM>, according to various embodiments, is electrically coupled to a power source <NUM> and may be configured to release the blowout panel <NUM> of the evacuation slide assembly <NUM> in response to the evacuation event and/or in response to electrical current flowing into the blowout panel actuator <NUM>.

In various embodiments, power source <NUM> comprises a battery, a capacitor, or any other suitable power source capable of electrically energizing blowout panel actuator <NUM>. In various embodiments, the release system <NUM> further includes a control unit <NUM> configured to regulate electric power supplied by the power source <NUM>. In various embodiments, the control unit <NUM> includes one or more controllers (e.g., processors) and one or more tangible, non-transitory memories capable of implementing digital or programmatic logic. In various embodiments, for example, the one or more controllers are one or more of a general purpose processor, digital signal processor (DSP), application specific integrated circuit (ASIC), field programmable gate array (FPGA), or other programmable logic device, discrete gate, transistor logic, or discrete hardware components, or any various combinations thereof or the like. In various embodiments, the control unit <NUM> controls, at least various parts of, and operation of various components of, the release system <NUM>.

The blowout panel actuator <NUM>, in accordance with various embodiments, is configured to release the blowout panel <NUM> of the evacuation slide assembly <NUM> in response to being electrically energized. That is, according to various embodiments, the blowout panel <NUM> may be at least partially retained in place by the blowout panel actuator <NUM> until an evacuation event and/or until the blowout panel actuator <NUM> is electrically energized by power source <NUM>. In response to the evacuation event and/or blowout panel actuator <NUM> being electrically energized (e.g., electrical current flowing into the blowout panel actuator <NUM> from power source <NUM>), the blowout panel actuator <NUM> may release the blowout panel <NUM>, thus allowing the blowout panel <NUM> to be jettisoned, in accordance with various embodiments. In various embodiments, the act of jettisoning of the blowout panel <NUM> may be accomplished indirectly via inflation of the evacuation slide.

In various embodiments, the blowout panel actuator <NUM> may include multiple actuators spaced apart from each other and distributed along a length of the packboard <NUM>. In various embodiments, the blowout panel actuator or blowout panel actuators <NUM> may be ball locks. The ball locks may engage a lip or other surface of the blowout panel <NUM> and thus may securely retain, or at least facilitate retaining, the blowout panel <NUM> in place over an opening to the packboard compartment. In response to the blowout panel actuator or blowout panel actuators <NUM> being electrically energized, the electrical energy may activate the blowout panel actuator or blowout panel actuators <NUM> to release the blowout panel <NUM>.

The release system <NUM> may further include a manual switch <NUM> for manually operating blowout panel actuator <NUM>, for example during a maintenance and/or repair procedure. Manually manipulating manual switch <NUM> may cause blowout panel actuator <NUM> to be electrically energized by power source <NUM>. Additional details pertaining to the blowout panel actuator <NUM> are included herein with reference to <FIG>.

In various embodiments, the release system <NUM> further includes a soft cover actuator <NUM> which may be electrically actuated. The soft cover actuator <NUM>, according to various embodiments, is electrically coupled to the power source <NUM> and may be configured to release the soft cover <NUM> of the evacuation slide assembly <NUM> in response to the evacuation event and/or in response to electrical current flowing into the soft cover actuator <NUM>. Additional details pertaining to the soft cover actuator <NUM> are included herein with reference to <FIG> and <FIG> through <FIG>.

With reference to <FIG>, the evacuation slide assembly <NUM> may comprise soft cover <NUM> containing evacuation slide <NUM>. Soft cover <NUM> may have lacing <NUM> to enclose soft cover <NUM> and to retain the evacuation slide <NUM>. Lacing <NUM> may be in a daisy chain or speed lacing configuration. The lacing <NUM> may have a key-loop that, once released or unlocked, allows the remainder of the lacing <NUM> to be unfurled. Thus, in response to releasing the key-loop, the evacuation slide <NUM> may be released (or may at least be releasable).

In various embodiments, the soft cover actuator <NUM> may be coupled to the lacing <NUM> and actuation of the soft cover actuator <NUM>, in response to being electrically energized, may unlock the key-loop or other such feature of the lacing <NUM>, thereby allowing the lacing <NUM> to be unfurled. In various embodiments, the lacing <NUM> may include a pin that locks the key-loop. The pin may be slidably coupled to the lacing <NUM> and may be coupled to the soft cover actuator <NUM>. Movement of the soft cover actuator <NUM> may cause the pin to move, thus unlocking the lacing <NUM>. In various embodiments, the soft cover actuator <NUM> may be an electrically drivable actuator pin, as described herein in further detail.

With reference to <FIG>, a schematic view of the release system <NUM> is illustrated, in accordance with various embodiments. Control unit <NUM> may receive an input signal <NUM> in response to the emergency exit door <NUM> opening and/or in response to an evacuation event. Input signal <NUM> may be received via a wired or wireless connection. In various embodiments, input signal <NUM> is received from a door position sensor. In various embodiments, input signal <NUM> is received from an onboard controller configured to indicate to release system <NUM> to deploy the emergency slide. In response to input signal <NUM>, control unit <NUM> may cause switch <NUM> and/or switch <NUM> to close to energize blowout panel actuator <NUM> and/or soft cover actuator <NUM> with power source <NUM>.

In various embodiments, switch <NUM> may be manually (e.g., via manual switch <NUM>) and/or electronically (e.g., via control unit <NUM>) opened and closed. In this regard, switch <NUM> may be referred to herein as a manual switch and/or an automatic switch. Moreover, it is contemplated herein that switch <NUM> may be separated into two separate switches; one automatic switch and one manual switch, both of which are individually and/or independently operable to close the power supply circuit to blowout panel actuator <NUM>.

In various embodiments, switch <NUM> may be electronically opened and closed to close the power supply circuit to soft cover actuator <NUM>. In various embodiments, control unit <NUM> operates switch <NUM> and switch <NUM> simultaneously or substantially simultaneously to release blowout panel <NUM> and soft cover <NUM>, respectively.

With reference to <FIG>, a ball lock actuator <NUM> is illustrated, in accordance with various embodiments. Blowout panel actuator <NUM> (see <FIG>) may be similar to ball lock actuator <NUM>, in accordance with various embodiments. Ball lock actuator <NUM> may include a frangible rod <NUM>, at least one ball bearing <NUM>, a nose fitting <NUM>.

In various embodiments, frangible rod <NUM> is coupled to housing <NUM> via a fastener <NUM>. In various embodiments, fastener <NUM> is a threaded nut threadingly coupled to frangible rod <NUM>. A lock washer <NUM> may be provided to secure nut fastener <NUM> with respect to frangible rod <NUM>.

Housing <NUM> may comprise a passage <NUM> for receiving electrical wire <NUM>. Electrical wire <NUM> may carry electrical current from power source <NUM> (see <FIG>) to SMA spring <NUM>. In this manner, SMA spring <NUM> may vary in length in response to being electrically energized to translate spindle <NUM> along longitudinal axis <NUM> with respect to nose fitting <NUM> and housing <NUM> to actuate ball lock actuator <NUM> between a locked state (see <FIG>) and an unlocked state (see <FIG>).

With particular focus on <FIG>, housing <NUM> comprises a main chamber <NUM>. Spindle <NUM> may comprise a flange <NUM> which divides the main chamber <NUM> into a first portion <NUM> and a second portion <NUM>. The SMA spring <NUM> may be disposed in the first portion <NUM> and the compression spring <NUM> may be disposed in the second portion <NUM>. In this manner, SMA spring <NUM> may be energized, via electrical wire <NUM>, which causes the SMA spring <NUM> to extend in length, thereby biasing the spindle <NUM> to retract into the housing <NUM> and compressing the compression spring <NUM> (see <FIG>). In response to SMA spring <NUM> being deenergized (i.e., SMA spring <NUM> is electrically decoupled from the power source), SMA spring <NUM> may decrease in length and compression spring <NUM> may increase in length (i.e., decompress) to bias the spindle <NUM> to extend from the housing <NUM> (see <FIG>).

With reference to <FIG>, SMA spring <NUM> is illustrated in a first state (also referred to herein as a deenergized state) with spindle <NUM> in an extended position and biasing ball bearings <NUM> outwards to project from nose fitting <NUM>. In the first state, compression spring <NUM> overcomes the bias of SMA spring <NUM> and biases spindle <NUM> to the extended position. In various embodiments, in the extended position, a first end of spindle <NUM> may abut nose fitting <NUM> and a second end of spindle <NUM> may abut compression spring <NUM>. Moreover, ball bearings <NUM> may abut the outer surface of spindle <NUM> to secure ball bearings <NUM> in the protruding position.

With reference to <FIG>, SMA spring <NUM> is illustrated in a second state (also referred to herein as an energized state) with spindle <NUM> in a retracted position. In the retracted position, spindle <NUM> is moved away from the ball bearings <NUM> to allow the ball bearings <NUM> to move inward toward longitudinal axis <NUM> and within the outer periphery of nose fitting <NUM>. In the second state, SMA spring <NUM> overcomes the bias of compression spring <NUM> and biases spindle <NUM> to the retracted position. In various embodiments, ball bearings <NUM> may abut the outer surface of frangible rod <NUM> when SMA spring <NUM> is in the second state. In various embodiments, spindle <NUM> may abut a shoulder <NUM> of housing <NUM> when SMA spring <NUM> is in the second state. Shoulder <NUM> partially defines main chamber <NUM>.

In various embodiments, spindle <NUM> comprises a hollow tube <NUM> extending longitudinally (i.e., parallel longitudinal axis <NUM>) from flange <NUM>. Frangible rod <NUM> may extend through hollow tube <NUM>. Frangible rod <NUM> and hollow tube <NUM> may be concentrically positioned about longitudinal axis <NUM>. In various embodiments, SMA spring <NUM> surrounds the spindle <NUM>. SMA spring <NUM> may surround the hollow tube <NUM>. SMA spring <NUM> may be disposed in main chamber <NUM> between flange <NUM> and nose fitting <NUM>.

<FIG> and <FIG> schematically illustrate a portion of a packboard <NUM> and a portion of a blowout panel <NUM>. Ball lock actuator <NUM> may be mounted to packboard <NUM>. With the ball bearings <NUM> extending from the periphery of nose fitting <NUM>, the ball bearings <NUM> may prevent the blowout panel <NUM> from moving longitudinally away from packboard <NUM>, thereby securing the blowout panel <NUM> to the packboard <NUM>. Stated differently, the blowout panel <NUM> may be clamped between the ball bearings <NUM> and the packboard <NUM>. In response to the SMA spring <NUM> being energized, the spindle <NUM> retracting, and the ball bearings <NUM> retracting into the nose fitting <NUM>, the blowout panel <NUM> may be released from packboard <NUM> (see <FIG>) to allow the inflatable evacuation slide to deploy.

With reference to <FIG>, a soft cover actuator <NUM> is illustrated, in accordance with various embodiments. Soft cover actuator <NUM> (see <FIG>) may be similar to soft cover actuator <NUM>, in accordance with various embodiments. Soft cover actuator <NUM> may include a nose fitting <NUM>, a SMA spring <NUM>, a spindle <NUM>, a compression spring <NUM>, and a housing <NUM>.

Housing <NUM> may comprise a passage <NUM> for receiving electrical wire <NUM>. Electrical wire <NUM> may carry electrical current from power source <NUM> (see <FIG>) to SMA spring <NUM>. In this manner, SMA spring <NUM> may vary in length in response to being electrically energized to translate spindle <NUM> along longitudinal axis <NUM> with respect to nose fitting <NUM> and housing <NUM> to actuate soft cover actuator <NUM> between a locked state (see <FIG>) and an unlocked state (see <FIG>).

With reference to <FIG>, SMA spring <NUM> is illustrated in a first state (also referred to herein as a deenergized state) with spindle <NUM> in an extended position and projecting longitudinally outwards from nose fitting <NUM>. In the first state, compression spring <NUM> overcomes the bias of SMA spring <NUM> and biases spindle <NUM> to the extended position. In various embodiments, in the extended position, a first end of spindle <NUM> may extend from nose fitting <NUM> and a second end of spindle <NUM> may abut compression spring <NUM>.

With reference to <FIG>, SMA spring <NUM> is illustrated in a second state (also referred to herein as an energized state) with spindle <NUM> in a retracted position. In the second state, SMA spring <NUM> overcomes the bias of compression spring <NUM> and biases spindle <NUM> to the retracted position. In various embodiments, spindle <NUM> may abut a shoulder <NUM> of housing <NUM> when SMA spring <NUM> is in the second state. Shoulder <NUM> partially defines main chamber <NUM>.

In various embodiments, spindle <NUM> comprises a hollow tube <NUM> extending longitudinally (i.e., parallel longitudinal axis <NUM>) from flange <NUM>. Compression spring <NUM> may extend into hollow tube <NUM>. In this manner, compression spring <NUM> is secured in the installed position with respect to housing <NUM> and spindle <NUM>. Compression spring <NUM> and hollow tube <NUM> may be concentrically positioned about longitudinal axis <NUM>.

With combined reference to <FIG>, <FIG>, and <FIG>, spindle <NUM> may be configured to couple to the key-loop or pin <NUM> of the lacing <NUM>. The arm of the soft cover actuator <NUM> (e.g., spindle <NUM> of soft cover actuator <NUM>) may be in an extended position when the soft cover actuator <NUM> is deenergized (i.e., when the SMA spring <NUM> is deenergized (e.g., relaxed and/or compressed)). Upon electrically energizing the soft cover actuator <NUM> (e.g., energizing the SMA spring <NUM>), the arm of the soft cover actuator <NUM> may retract into the housing (e.g., spindle <NUM> may retract into housing <NUM>), thus sliding the pin <NUM> or otherwise unlocking the key-loop of the lacing <NUM> to allow the lacing <NUM> to unfurl and release the evacuation slide <NUM> from the soft cover <NUM>.

With reference to <FIG>, a SMA spring <NUM> is illustrated, in accordance with various embodiments. SMA spring <NUM> (see <FIG>) and/or SMA spring <NUM> (see <FIG>) may be similar to SMA spring <NUM>, in accordance with various embodiments. SMA spring <NUM> may comprise two concentrically oriented helical coils connected at a first end <NUM> and terminating at a second end <NUM>. In this manner, SMA spring <NUM> may be referred to herein as a double coil spring comprising an inner coil <NUM> and an outer coil <NUM>. The outer coil <NUM> and inner coil <NUM> may wind in different directions. For example, if the outer coil <NUM> is a right-hand winding, then the inner coil <NUM> is a left-hand winding, or vice versa.

Both ends of SMA spring <NUM> may be located at second end <NUM>. In this manner, electric wires may be attached at a common location (e.g., at the same end of SMA spring <NUM>) for ease of routing wires to SMA spring <NUM>. For example, passage <NUM> (see <FIG>) may be located at second end <NUM> of SMA spring <NUM>. In <FIG>, a circuit diagram of a power source is schematically shown coupled to the SMA spring <NUM>. A first terminus <NUM> of the inner coil <NUM> may be coupled to a first terminal (e.g., a negative terminal in the illustrated embodiment) of the power source and a second terminus <NUM> of the outer coil <NUM> may be coupled to a second terminal (e.g., a positive terminal in the illustrated embodiment) of the power source. It should be understood that the polarity of the SMA spring <NUM> may be reversed as desired without departing from the scope of the appended claims. In this manner, electric current may be supplied to the SMA spring <NUM>.

With reference to <FIG>, SMA spring <NUM> is illustrated in a relaxed stated (i.e., without being energized). SMA spring <NUM> may comprise a first length <NUM> in the relaxed state.

With reference to <FIG>, SMA spring <NUM> is illustrated in an energized stated. SMA spring <NUM> may comprise a second length <NUM> in the energized state. The second length <NUM> is greater than the first length <NUM>. SMA spring <NUM> may increase in length to a predefined length (e.g., second length <NUM>) when electrically energized and may gradually return to its default length (e.g., first length <NUM>) after the electricity is cut-off. When the power supply circuit is closed, the electrical current flows through the SMA spring <NUM> heating it due to the resistance inherent in the SMA material of which the SMA spring <NUM> is made. Heating of the SMA spring <NUM> to a sufficient temperature may cause the SMA material properties to change from martensite to austenite crystalline structure, which causes a length change in the SMA spring <NUM>. Changing the electrical current changes the temperature and therefore changes the length of the SMA spring <NUM>, which is used to actuate and de-actuate the actuator (e.g., blowout panel actuator <NUM> and/or soft cover actuator <NUM> of <FIG>) to control the movement of the actuator in at least the longitudinal direction (e.g., parallel to longitudinal axis <NUM> of <FIG> and/or longitudinal axis <NUM> of <FIG>). In various embodiments, SMA spring <NUM> comprises a nickel-titanium alloy.

<FIG> illustrates a schematic flow chart diagram of a method <NUM> of deploying an evacuation slide of an aircraft, in accordance with various embodiments. The method <NUM> may include flowing fluid from a fluid source, such as the charged tank <NUM>, to the evacuation slide via the fluid delivery manifold <NUM> at step <NUM>. The method <NUM> may further include actuating a first actuator by electrically energizing the SMA spring of the first actuator to release a blowout panel at step <NUM> and actuating a second actuator by electrically energizing the SMA spring of the second actuator to release a soft cover at step <NUM>.

Claim 1:
A release system (<NUM>) for an evacuation slide assembly of an aircraft, the release system comprising:
a blowout panel (<NUM>); and
a first actuator (<NUM>) comprising a first housing (<NUM>), a first shape memory alloy spring (<NUM>), a first compression spring (<NUM>), and a first spindle (<NUM>);
wherein the first shape memory alloy spring (<NUM>) is configured to bias the first spindle to retract into the first housing in response to being electrically energized to deploy the blowout panel (<NUM>).