Patent Description:
An airplane fuselage includes a fuselage wall and a door for opening and closing an opening in the fuselage wall. A rubber seal element is included to provide a sealed interface between the door and the fuselage wall. Degradation of this seal element may lead to gas leakage (e.g., atmospheric pressure leakage) across the sealed interface and out of the airplane fuselage. However, it may be difficult to detect such gas leakage until the leak is relatively large using existing airplane decompression detection systems. There is a need in the art therefore for systems and methods for detecting a fluid leak / an unexpected change in pressure at, inter alia, an airplane door.

<CIT> discloses a prior art assembly according to the preamble of claim <NUM>.

<CIT> discloses an aircraft door leakage detection system based on fluid pressure detection.

The invention is defined by independent claims <NUM> and <NUM>.

According to an aspect of the present invention, an assembly is provided for an aircraft. This aircraft assembly includes a fuselage and a second system. The fuselage includes a wall and a hatch configured to close an opening in the wall. The sensor system includes an optical fiber, a transmitter and a receiver. The optical fiber is arranged at an interface between the hatch and the wall. The transmitter is configured to transmit first electromagnetic radiation into the optical fiber. The receiver is configured to detect second electromagnetic radiation received from the optical fiber to provide receiver data. The sensor system is configured to detect fluid leakage across the interface between the hatch and the wall based on the receiver data.

According to another aspect of the present invention, a method is provided involving an aircraft fuselage including a wall and a hatch. During this method, first electromagnetic radiation is transmitted into an optical fiber. The optical fiber is arranged at an interface between the hatch and the wall. The hatch is configured to close an opening in the wall. Actual second electromagnetic radiation received from the optical fiber is detected. A fluid leak across the interface between the hatch and the wall is detected based on a wavelength shift between the actual second electromagnetic radiation and expected second electromagnetic radiation.

The following optional features may be applied to any of the above aspects of the invention.

The sensor system may also be configured to process the receiver data to determine a difference between the second electromagnetic radiation and expected electromagnetic radiation. The sensor system may still also be configured to detect the fluid leakage based on the difference between the second electromagnetic radiation and the expected electromagnetic radiation.

The difference between the second electromagnetic radiation and the expected electromagnetic radiation may be or include a wavelength shift between the second electromagnetic radiation and the expected electromagnetic radiation.

The sensor system may also be configured to determine a flowrate of the fluid leakage across the interface between the hatch and the wall based on the receiver data.

The sensor system may also be configured to provide an indicator signal when the flowrate of the fluid leakage across the interface is greater than a threshold.

The sensor system may also be configured to determine a location of the fluid leakage across the interface.

The optical fiber may include a grating configured to shift a wavelength of the first electromagnetic radiation.

The first electromagnetic radiation may interact with and pass through the grating to at least partially provide the second electromagnetic radiation.

The second electromagnetic radiation may include a reflection of at least a portion of the first electromagnetic radiation by the grating.

The optical fiber may include a plurality of gratings arranged at discrete locations along the interface between the hatch and the wall. The gratings may include a first grating and a second grating. The first grating may be configured to reflect a first wavelength of electromagnetic radiation. The second grating may be configured to reflect a second wavelength of electromagnetic radiation.

The optical fiber may include a plurality of gratings arranged at discrete locations along the interface between the hatch and the wall. Each of the gratings may be associated with unique electromagnetic radiation transmitted into the optical fiber.

The optical fiber may extend longitudinally between a first end and a second end. The transmitter and the receiver may be arranged at the first end.

The optical fiber may extend longitudinally between a first end and a second end. The transmitter may be arranged at the first end. The receiver may be arranged at the second end.

The aircraft assembly may also include a seal element arranged at the interface between the hatch and the wall. The optical fiber may be disposed along and outside of the seal element.

The aircraft assembly may also include a seal element arranged at the interface between the hatch and the wall. At least a portion of the optical fiber may be disposed within the seal element.

The optical fiber may be disposed at an exterior side of the interface between the hatch and the wall.

The optical fiber may be disposed at an interior side of the interface between the hatch and the wall.

The aircraft assembly may also include a second sensor system including a second optical fiber, a second transmitter and a second receiver. The second optical fiber may be arranged at the interface between the hatch and the wall. The second transmitter may be configured to transmit third electromagnetic radiation into the second optical fiber. The second receiver may be configured to detect fourth electromagnetic radiation received from the second optical fiber to provide second receiver data. The second sensor system may be configured to detect fluid leakage across the interface between the hatch and the wall based on the second receiver data.

<FIG> is an illustration of an aircraft <NUM>. This aircraft <NUM> may be configured as an airplane such as, but not limited to, a passenger plane or a cargo plane. The aircraft <NUM> of <FIG> includes an aircraft fuselage <NUM>. This aircraft fuselage <NUM> includes a fuselage wall <NUM> and one or more fuselage hatches <NUM>; e.g., doors, removable panels, etc. Each hatch <NUM> is configured to open and close a respective opening <NUM> in the wall <NUM>.

Referring to <FIG>, in a closed position, each hatch <NUM> engages the wall <NUM> at a hatch-wall interface <NUM> between the respective hatch <NUM> and the wall <NUM>. The hatch-wall interface <NUM> of <FIG> is configured as a sealed interface with a polymer hatch seal element <NUM> (e.g., a rubber seal element) arranged between and engaging (e.g., contacting, pressed against) a surface <NUM> of the wall <NUM> and a surface <NUM> of the respective hatch <NUM>. The seal element <NUM> is located at the hatch-wall interface <NUM>. The seal element <NUM> of <FIG> extends longitudinally along the hatch-wall interface <NUM> and about (e.g., completely around) the respective wall opening <NUM>. The seal element <NUM> of <FIG> may thereby seal a gap between the wall <NUM> and the respective hatch <NUM> at the hatch-wall interface <NUM>.

<FIG> schematically illustrates an assembly <NUM> for the aircraft <NUM>. This aircraft assembly <NUM> includes the wall <NUM>, one or more of the hatches <NUM> and one or more sensor systems <NUM>. Each of the sensor systems <NUM> is configured to monitor the hatch-wall interface <NUM> between the wall <NUM> and a respective one of the hatches <NUM>. More particularly, each sensor system <NUM> is configured to detect fluid leakage (e.g., airflow) across the hatch-wall interface <NUM> between the wall <NUM> and the respective hatch <NUM>.

Referring to <FIG>, each sensor system <NUM> includes an optical fiber <NUM> (e.g., a strand of fiber optics), an electromagnetic radiation transmitter <NUM> and an electromagnetic radiation receiver <NUM>. Each sensor system <NUM> also includes a processing system <NUM>.

The optical fiber <NUM> is arranged at (e.g., on, adjacent or proximate) the hatch-wall interface <NUM> with the seal element <NUM>. The optical fiber <NUM> extends along a longitudinal centerline between a first end <NUM> of the optical fiber <NUM> and a second end <NUM> of the optical fiber <NUM>.

The optical fiber <NUM> of <FIG> is configured with one or more internal gratings 54A-H (generally referred to as "<NUM>"; schematically shown) (e.g., fiber Bragg gratings (FBG)) within a fiber core of the optical fiber <NUM>. These gratings <NUM> are arranged (e.g., distributed) at discrete locations along the longitudinal centerline between the fiber first end <NUM> and the fiber second end <NUM>. Each of the gratings <NUM> is configured to reflect one or more specific wavelengths of electromagnetic radiation (e.g., light) while permitting the remaining wavelengths of the electromagnetic radiation to pass / travel therethrough. Each grating <NUM> may thereby filter the one or more specific wavelengths of electromagnetic radiation. Each of the gratings <NUM> may be provided by forming a periodic variation in a refractive index of the fiber core of the optical fiber <NUM>; e.g., by constructing a distributed Bragg reflector within a short segment of the optical fiber <NUM>.

Each of the gratings <NUM> within the optical fiber <NUM> is tuned for (e.g., configured to reflect / filter) a different wavelength (or wavelengths) of the electromagnetic radiation. The first grating 54A, for example, may be tuned for a first wavelength of the electromagnetic radiation. The second grating 54B may be tuned for a second wavelength of the electromagnetic radiation which is different than the first wavelength of the electromagnetic radiation. The second wavelength of the electromagnetic radiation may also be separated (e.g., spaced) from the first wavelength of the electromagnetic radiation by one or more intermediate wavelengths of the electromagnetic radiation to provide further differentiation between the different wavelengths of the electromagnetic radiation.

The transmitter <NUM> is configured transmit one or more wavelengths (e.g., a spectrum) of the electromagnetic radiation into the optical fiber <NUM>. The transmitter <NUM>, for example, may be configured as an electromagnetic radiation emitting device. The transmitter <NUM> of <FIG> is disposed at and/or otherwise in communication (e.g., optically coupled) with the fiber first end <NUM>.

The receiver <NUM> is configured to receive radiation (e.g., optical) information via electromagnetic radiation received from the optical fiber <NUM>. The receiver <NUM> is also configured to provide receiver data generated from and/or indicative of the radiation information. The receiver <NUM>, for example, may be configured as an optical receptor or any other electromagnetic radiation receptor / sensor. The receiver <NUM> of <FIG> is disposed at and/or otherwise in communication (e.g., optically coupled) with the fiber second end <NUM>. However in other embodiments, referring to <FIG>, the receiver <NUM> may alternatively be disposed at and/or otherwise in communication with the fiber first end <NUM>.

Referring again to <FIG>, the processing system <NUM> is in signal communication with the transmitter <NUM> and the receiver <NUM>. The processing system <NUM>, for example, may be hardwired and/or wirelessly coupled with the transmitter <NUM> and the receiver <NUM>.

The processing system <NUM> may be implemented with a combination of hardware and software. The hardware may include a memory and at least one processing device, which processing device may include one or more single-core and/or multi-core processors. The hardware may also or alternatively include analog and/or digital circuitry other than that described above.

The memory is configured to store software (e.g., program instructions) for execution by the processing device, which software execution may control and/or facilitate performance of one or more operations such as those described in the method below. The memory may be a non-transitory computer readable medium. For example, the memory may be configured as or include a volatile memory and/or a nonvolatile memory. Examples of a volatile memory may include a random access memory (RAM) such as a dynamic random access memory (DRAM), a static random access memory (SRAM), a synchronous dynamic random access memory (SDRAM), a video random access memory (VRAM), etc. Examples of a nonvolatile memory may include a read only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a computer hard drive, etc..

<FIG> is a flow diagram of a method <NUM> involving an aircraft such as the aircraft <NUM> described above. This method <NUM> is described below for detecting fluid (e.g., air) leakage across a select one of the hatch-wall interfaces <NUM> (see <FIG>) during aircraft flight. However, the method <NUM> may alternatively be performed for detecting fluid leakage across more than one (e.g., all) of the hatch-wall interfaces <NUM>. Furthermore, while the method <NUM> is described as being performed during aircraft flight, the present disclosure is not limited thereto.

In step <NUM>, first electromagnetic radiation (e.g., a first spectrum of light) is transmitted into the optical fiber <NUM>. The processing system <NUM>, for example, may signal the transmitter <NUM> to emit the first electromagnetic radiation, which enters the optical fiber <NUM> at the fiber first end <NUM>.

In step <NUM>, the first electromagnetic radiation travels within the optical fiber <NUM> and interacts with the one or more gratings <NUM> to provide second electromagnetic radiation (e.g., a second spectrum of light). The first electromagnetic radiation input by the transmitter <NUM>, for example, travels through a first segment (e.g., 56A) of the optical fiber <NUM> to the first grating 54A. The first electromagnetic radiation interacts with the first grating 54A, where at least one wavelength of the first electromagnetic radiation is reflected and the remaining wavelengths of the first electromagnetic radiation pass through the first grating 54A to provide first filtered electromagnetic radiation. This first filtered electromagnetic radiation travels through a second segment (e.g., 56B) of the optical fiber <NUM> from the first grating 54A to the second grating 54B. The first filtered electromagnetic radiation interacts with the second grating 54B, where at least one wavelength of the first filtered electromagnetic radiation is reflected and the remaining wavelengths of the first filtered electromagnetic radiation passes through the second grating 54B to provide second filtered electromagnetic radiation. This electromagnetic radiation propagation and filtering process is repeated along the optical fiber <NUM> with each grating <NUM> (e.g., 54C-H) until the second electromagnetic radiation is provided following interaction (e.g., filtering) with the last grating <NUM>; e.g., the eighth grating <NUM> in <FIG>. Thus, the second electromagnetic radiation at the fiber second end <NUM> is different than (e.g., a derivation of) the first electromagnetic radiation at the fiber first end <NUM>.

In step <NUM>, receiver data (e.g., sensor data) is provided. The receiver <NUM>, for example, detects, captures and/or otherwise receives at least a portion or all of the second electromagnetic radiation at the fiber second end <NUM>. The receiver <NUM> may convert the received second electromagnetic radiation into the receiver data, which receiver data is indicative of the received second electromagnetic radiation.

In step <NUM>, at least one condition of the hatch-wall interface <NUM> is determined. The processing system <NUM>, for example, receives the receiver data from the receiver <NUM>. The processing system <NUM> may process this receiver data to determined whether or not there is fluid leakage across the hatch-wall interface <NUM>. The actual receiver data provided by the receiver <NUM>, for example, may be compared to (e.g., predetermined or modeled) expected receiver data, which expected receiver data is data that is expected to be received by the receiver <NUM> based on one or more parameters such as, but not limited to, a fully sealed hatch-wall interface <NUM>, current flight conditions and/or current aircraft cabin conditions. The actual receiver data may be different than the expected receiver data where, for example, a fluid leak (e.g., air pressure leakage) forms across the hatch-wall interface <NUM>. Such a fluid leak (e.g., air pressure leakage) may cause a local drop in fluid (e.g., air) temperature at the location of the fluid leak, which drop in temperature may alter the (e.g., reflection, filtering) characteristics of one or more nearby gratings <NUM>. For example, the drop in temperature may cause a nearby grating <NUM> to physically contract. This change in the grating characteristics may result in provision of altered filtered electromagnetic radiation received (e.g., detected) by the receiver <NUM> such that, for example, there is one or more wavelength shifts / differences between the actual receiver data and the expected receiver data. The magnitude of the wavelength shift(s) are indicative of a temperature at the grating(s) <NUM>, and may be used to predict a flowrate of the fluid leaking across the hatch-wall interface <NUM> based on the temperature.

Where the actual receiver data is the same as the expected receiver data, the processing system <NUM> may determine that the condition of the hatch-wall interface <NUM> is fully operational and serviceable. In some embodiments, slight fluid leakage across the hatch-wall interface <NUM> may be expected, acceptable and/or accommodatable by an aircraft cabin pressurization system. In such embodiments, the processing system <NUM> may also determine that the condition of the hatch-wall interface <NUM> is fully operational and serviceable where the magnitude of the wavelength shift(s) / difference between the actual receiver data and the expected receiver data is less than a first threshold. Where the magnitude of the wavelength shift(s) / difference between the actual receiver data and the expected receiver data is equal to or greater than the first threshold, but less than a second threshold, the processing system <NUM> may determine that the hatch-wall interface <NUM> is still serviceable, but no longer fully operational. With such a determination, the processing system <NUM> may provide a maintenance notification signal (e.g., an alert) such that future maintenance may be planned and performed. Thus, the aircraft <NUM> may finish its current flight (and possibly one or more additional flights) since the fluid leakage is caught / detected at an early stage. Where the magnitude of the wavelength shift(s) / difference between the actual receiver data and the expected receiver data is equal to or greater than the second threshold, the processing system <NUM> may determine that the condition of the hatch-wall interface <NUM> is no longer serviceable. With such a determination, the processing system <NUM> may provide a notification signal (e.g., an alert) such that (e.g., immediate or otherwise timely) action may be taken. For example, the aircraft <NUM> may be diverted to a closer airport or maintenance may be performed at the destination airport; but, deployment of oxygen masks may be averted.

The processing system <NUM> may also determine a predicted location of the fluid leak when that leak is detected as described above. For example, since each of the gratings 54A-H within the optical fiber <NUM> is tuned for (e.g., configured to reflect / filter) an individualized / different wavelength (or wavelengths) of the electromagnetic radiation, the processing system <NUM> may analyze the receiver data to determine which grating <NUM> was most likely affected to cause the wavelength shift(s) in the actual receiver data. Maintenance personnel may thereby inspect a certain area of the hatch-wall interface <NUM> and the associated portion of the seal element <NUM> to determine what repair or part (e.g., seal element) replacement is needed.

As described above, the method <NUM> may be performed for each of the sensor systems <NUM> such that each of the hatch-wall interfaces <NUM> is monitored for fluid leakage. Each of the processing systems <NUM> of <FIG> may be in signal communication (e.g., hardwired and/or wirelessly coupled) with a central processing system <NUM>; e.g., a controller. This central processing system <NUM> may receive the notification signal(s) from the sensor system(s) <NUM>, and then relay notification information to a pilot and/or other personnel. The central processing system <NUM> may also or alternatively store the notification information for consideration (e.g., review, analysis, etc.) by, for example, a ground maintenance crew. Of course, in other embodiments, some or all of the sensor systems <NUM> may share a single central processing system <NUM> where the processing systems <NUM> (see <FIG>, <FIG>) are integrated into the central processing system <NUM>. In such embodiments, however, the gratings <NUM> in each sensor system <NUM> may be discretely tuned such that the wavelength shift(s) may identify which one of the hatch-wall interfaces <NUM> is associated with the fluid leakage.

The second electromagnetic radiation described above includes the wavelength(s) of electromagnetic radiation that pass through the various gratings <NUM> within the optical fiber <NUM>. In such embodiments, referring to <FIG>, the transmitter <NUM> may be located at the fiber first end <NUM> and the receiver <NUM> may be located at the fiber second end <NUM>. Such an arrangement may be implemented for various installations including, but not limited to, those where a longitudinal length of the optical fiber <NUM> is relatively short and both fiber ends <NUM> and <NUM> are open. However, in other embodiments, the second electromagnetic radiation may include the electromagnetic radiation that is reflected by the gratings <NUM>. In such embodiments, referring to <FIG>, the transmitter <NUM> and the receiver <NUM> may both be located at a common fiber end <NUM>, <NUM>; e.g., the fiber first end <NUM>. Such an arrangement may be implemented for various installations including, but not limited to, those where the longitudinal length of the optical fiber <NUM> is relatively long and one of the ends <NUM>, <NUM> (e.g., the fiber second end <NUM>) is closed; e.g., capped.

In some embodiments, referring to <FIG>, at least a portion or an entirety of the optical fiber <NUM> may be disposed along and outside of the seal element <NUM> at the hatch-wall interface <NUM>. The optical fiber <NUM>, for example, may be located next to and may extend longitudinally along an exterior surface <NUM> of the seal element <NUM>. The optical fiber <NUM> may engage (e.g., contact) the seal element <NUM>. Alternatively, the optical fiber <NUM> may be (e.g., slightly) spaced from and disengaged with (e.g., not contacting) the seal element <NUM>.

In some embodiments, referring to <FIG>, at least a portion or an entirety of the optical fiber <NUM> may be disposed along and within the seal element <NUM> at the hatch-wall interface <NUM>. The optical fiber <NUM>, for example, may be integrated into material <NUM> of / a body <NUM> of the seal element <NUM>.

In some embodiments, referring to <FIG>, at least a portion or an entirety of the optical fiber <NUM> may be disposed at (e.g., on, towards, etc.) an exterior side <NUM> of the hatch-wall interface <NUM>. The optical fiber <NUM>, for example, may be located closer to the exterior side <NUM> of the hatch-wall interface <NUM> than an interior side <NUM> of the hatch-wall interface <NUM>. The exterior side <NUM> of the hatch-wall interface <NUM> is next to or proximate an external environment <NUM> outside of the aircraft fuselage <NUM>. The interior side <NUM> of the hatch-wall interface <NUM> is next to or proximate an internal environment <NUM> inside of the aircraft fuselage <NUM>; e.g., the aircraft cabin.

In some embodiments, referring to <FIG>, at least a portion or an entirety of the optical fiber <NUM> may be disposed at (e.g., on, towards, etc.) the interior side <NUM> of the hatch-wall interface <NUM>. The optical fiber <NUM>, for example, may be located closer to the interior side <NUM> of the hatch-wall interface <NUM> than the exterior side <NUM> of the hatch-wall interface <NUM>.

In some embodiments, referring to <FIG>, each hatch-wall interface <NUM> may be associated with a single sensor system <NUM>. In other embodiments, referring to <FIG>, one or more of the hatch-wall interfaces <NUM> may each be associated with a plurality of the sensor systems 40A and 40B. One of these sensor systems 40A may be disposed at the exterior side <NUM> of the hatch-wall interface <NUM>, and the other one of the sensor systems <NUM> may be disposed at the interior side <NUM> of the hatch-wall interface <NUM>. The multiple sensor systems <NUM> may thereby provide redundancy to reduce or eliminate provision of false positives.

While various embodiments of the present invention have been disclosed, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the invention as defined by the claims.

Claim 1:
An assembly (<NUM>) for an aircraft (<NUM>), comprising:
a fuselage (<NUM>) including a wall (<NUM>) and a hatch (<NUM>) configured to close an opening (<NUM>) in the wall (<NUM>); and
a sensor system (<NUM>) including an optical fiber (<NUM>), a transmitter (<NUM>) and a receiver (<NUM>), the optical fiber (<NUM>) arranged at an interface (<NUM>) between the hatch (<NUM>) and the wall (<NUM>), the transmitter (<NUM>) configured to transmit first electromagnetic radiation into the optical fiber (<NUM>), the receiver (<NUM>) configured to detect second electromagnetic radiation received from the optical fiber (<NUM>) to provide receiver data;
characterised in that:
the sensor system (<NUM>) is configured to detect fluid leakage across the interface (<NUM>) between the hatch (<NUM>) and the wall (<NUM>) based on the receiver data.