Patent ID: 12234037

DETAILED DESCRIPTION

The present disclosure relates to apparatuses and methods that facilitate the maintenance of levered landing gears by monitoring the condition of the stop pads of such landing gears. An aircraft with levered landing gear employs the landing gear in an extended position to give additional height to the landing gear compared to the static position to thereby affect the angles of attack possible during takeoff and/or landing. While that aircraft is on the ground (e.g., resting, taxiing), the levered landing gear of the aircraft are in a static position in which the stop pads that support the weight of the aircraft are subject to various static, dynamic, and impact loads. The contacting surfaces of the stop pads, as well as other portions of the stop pads, are not visible while in the static position, which prevents maintenance and service personnel from inspecting the stop pads. To inspect the stop pads, the aircraft must be lifted off of its landing gear so that the levered landing gear may travel to an extended position in which the stop pads are visible. As will be appreciated, lifting an aircraft takes the aircraft out of service for a significant period of time, and thus can be very costly to the operators of the aircraft.

To reduce the costs associated with employing levered landing gears and the servicing thereof, the stop pads are often inspected on a scheduled basis (allowing the downtime to be predictable and co-scheduled with other maintenance) and are made of robust materials to extend the life of the stop pads past the scheduled maintenance periods. As will be appreciated, scheduled maintenance may result in premature replacement of parts, such as a pad with a five-year operation life but a three-year inspection schedule being replaced after only three years of operation. As will also be appreciated, the reliance on scheduled maintenance can lead to over-engineered parts being used, which increase the cost of the landing gear and result in heavier landing gear assemblies (affecting cost of the aircraft and the fuel efficiency of the aircraft in turn).

The present disclosure presents systems and methods to inspect the stop pads outside of the scheduled maintenance periods, thus enabling conditional maintenance to be performed in addition to the scheduled inspection and/or servicing of the levered landing gears. Various sensors are included in the stops pads and the levered landing gear assemblies that monitor the health of the stop pads and alert maintenance personnel when a non-conformance from the operational profile of the stop pad is noticed. Depending on the sensors used, non-conformances include the thicknesses of the pads, the surface conditions of the pads, whether the paired stop pads are making consistent contact with one another, and whether debris is present on the pads.

FIGS.1A-Cillustrate various views of an example levered landing gear100to highlight the operation of the stop pads that will be monitored according to embodiments of the present disclosure.FIG.1Aillustrates a lateral cutaway view of an example levered landing gear100in the extended position, whileFIG.1Billustrates a lateral cutaway view of that example levered landing gear100in the static position.FIG.1Cillustrates an isometric view of an example levered landing gear100in the extended position. Depending on the view presented, a given component may be fully or partially obscured by another component. Therefore, one or more portions of a given component may be labeled with the same reference number for ease in identifying a given component in the illustrated views. Multiple instances of a given component are differentiated from one another by the use of a letter in conjunction with the reference number. One of ordinary skill in the art will appreciate that the illustrations provide a set of non-limiting examples of some of the various shapes, dimensions, and arrangements possible for a levered landing gear100and its components.

For ease of understanding, the current disclosure focuses its explanation of a first shock strut110, a second shock strut120, a truck lever130, a connecting link140, a pivot joint150, a strut pad160, a truck pad170, the stop joint180formed by the strut pad160and the truck pad170, a landing gear axle190, and various sensors for use with the levered landing gear, although one of ordinary skill in the art will appreciate that additional components are included in a levered landing gear100that are not discussed in detail herein. Collectively, the strut pad160and the truck pad170may be referred to as “stop pads,” and either the strut pad160or the truck pad170may be referred to as a “first” stop pad and the other referred to as a “second” stop pad. Similarly, the various features of the stop pads may be referred to by the ordinal designators used with the associated stop pad, such as, for example, a “first contact surface” referring to the contact surface of the first stop pad (either the strut pad160or the truck pad170).

The first shock strut110has a longitudinal axis having a first end111, which connects with the aircraft, and a second end112, which pivotally connects with the truck lever130via a first pivot joint150a. The first shock strut110, at or near the second end112, includes the strut pad160, which has a contact surface161. Additional reference will be made to a mounted surface162of the strut pad160, which is in contact with the body of the first shock strut110, and is not visible in certain illustrations of the embodiments. Similarly, a strut pad thickness163is defined by the distance between the contact surface161and the mounted surface162. In various embodiments, the strut pad160and the surrounding structure of the first shock strut110define one or more cavities in which various sensors are disposed. In some embodiments, the various sensors extend through the strut pad160or are associated with a through-hole in the contact surface161.

The second shock strut120is disposed concentrically with the first shock strut110, and shares a longitudinal axis with the first shock strut110. A first end121of the second shock strut120is located within a cavity defined by the first shock strut110, and the position of the first end121of the second shock strut120will vary as the second shock strut120extends to and from the extended position and the static position along the longitudinal axis shared with the first shock strut110. The second end122of the second shock strut120is coupled to the truck lever130via a connection link140. The connection link140is connected with the second shock strut120via a second pivot joint150band is connected with the truck lever130via a third pivot joint150c.

The truck lever130is coupled to the first shock strut110and the second shock strut120such that the second shock strut120, as it extends to and from the extended and static positions, pivots the truck lever130relative to the first shock strut110. The truck lever is coupled at a first end131with the first shock strut110via the first pivot joint150aand is coupled at a second end132with a landing gear axle190, by which the wheels may be mounted with the levered landing gear100.

The truck lever130includes the truck pad170, which has a contact surface171, configured to interface with the contact surface161of the strut pad160and thereby form the stop joint180when the truck lever130is in the static position. Additional reference will be made to a mounted surface172of the truck pad170, which is in contact with the body of the truck lever130, and is not visible in certain illustrations of the embodiments.

The various sensors used in one or more embodiments of the present disclosure are disposed with the levered landing gear100at various positions to measure conditions of the stop joint180to ensure the health of the mechanical components of the levered landing gear100. The types of sensors; where those sensors are disposed of in the levered landing gear100; the conditions of the stop joint180that are measured; whether a first sensor is used alone, part of a sensor array, or jointly with a second sensor; etc.; may vary in one or more embodiments of the present disclosure.

In various embodiments, the materials from which the strut pad160is constructed may be the same as or vary from the materials used for the first shock strut110. Similarly, the materials from which the truck pad170is constructed may be the same as or vary from those materials used in the truck lever130. In various embodiments, each of the strut pad160and the truck pad170are replaceable elements separable from the respective first shock strut110and the truck lever130, although in some embodiments one or more of the strut pad160and the truck pad170may be designated regions of the first shock strut110or the truck lever130, respectively. In some embodiments, the material that the strut pad160is made of is a harder material than the material than the truck pad170is made of, such as, for example, a steel versus a bronze (e.g., CuNiSn), so that wear can be observed more readily in one of the pads.

The stop joint180is formed by the strut pad160and the truck pad170when the landing gear100is in the static position. The contacting surfaces of the strut pad160and the truck pad170(e.g., the contact surface161and the contact surface171) come into contact and help bear the weights and forces applied by the aircraft to the wheels. Over time, wear on the contacting surfaces will erode one or more of the strut pad160and the truck pad170, contaminants may corrode one or more of the contact surfaces, and cracks, scratches, gouges, etc. may form. Additionally, various debris and contaminants may be introduced into the stop joint180, which may damage the one or more of the strut pad160and the truck pad170if not removed.

In the extended position, a levered landing gear100provides additional height for the aircraft relative to the static position. As the second shock strut120extends, the connecting link140translates the vertical motion of the second shock strut120to pivot the truck lever130about the first pivot joint150a. As shown in the illustrated embodiments, the third pivot joint150cis located between the first pivot joint150aand the landing gear axle190so that as the second shock strut120extends to the extended position, additional height is added to the levered landing gear100. The amount of height added to the levered landing gear100roughly corresponds to the distance between the first pivot joint150aand the landing gear axle190. As the levered landing gear100extends to the extended position, the stop joint180opens, moving the strut pad160and the truck pad170away from one another and exposing the respective contact surfaces (i.e., contact surface161and the contact surface171).

As will be appreciated, the contacting surfaces of the stop joint180are obscured by one another when the levered landing gear100is in the static position, rendering maintenance personnel unable to visually inspect the contact surface161of the strut pad160or the contact surface171of the truck pad170. However, the levered landing gear100is not typically in the extended position, where the contact surfaces are visible, except during takeoff and landing. Therefore, for maintenance personnel to view the contact surfaces, the aircraft is lifted or jacked to remove its weight from the landing gear100so that the levered landing gear100may be placed in the extended position for visual inspection of the contact surfaces. These “lifting” or “jacking” operations are typically conducted on a scheduled basis (e.g., every X flight hours, every Y months) as the operations take the aircraft out of service for extended periods of time. The various sensors discussed in the present disclosure provide opportunities to evaluate the health of the stop joint180in addition to the scheduled maintenance inspections, and several example sensors are discussed in greater detail in regard toFIGS.2-4.

FIG.2illustrates a detailed view200of a camera sensor210integrated in an example levered landing gear100according to an embodiment of the present disclosure. A camera sensor210is focused on some or all of a contact surface of a stop pad and is configured or operable to measure a visual condition of a contact surface and/or to provide images of the contact surface to maintenance personnel to corroborate the findings of any other sensors in use in the levered landing gear100. AlthoughFIG.2illustrates one camera sensor210integrated in the strut pad160and the first shock strut110, it will be appreciated that a camera sensor210may also be integrated in the truck pad170and the truck lever130, or in a mount external to both the strut pad160and the truck pad170, and that more than one camera sensor210may be employed in an array.

The camera sensor210includes a digital camera that is in communication with a computing device240. In various embodiments, the camera sensor210receives power via camera cabling230, which may also be used to communicate the images captured by the camera sensor210to the computing device240. In other embodiments, the camera cabling230may also be used to communicate with an external computing device, such as a diagnostic terminal.

In various embodiments, the camera sensor210is a camera (or array of cameras) capable of capturing three-dimensional (3D) images, although two-dimensional (2D) camera sensor210may also be employed. The camera sensor210includes an appropriate lens to focus the camera sensor210on the desired portion or portions of the contact surfaces to monitor (e.g., a wide angle lens, a multi-focal lens). The camera sensor210is able to automatically focus, and thus is able to capture images of the contact surface at various stages of extension between the extended and static positions of the levered landing gear100as the contact surfaces approach or recede from one another. In some embodiments, the camera sensor210includes a light source that may be activated or deactivated to ensure a consistent light level in the images of the contact surfaces captured by the camera sensor210.

The camera sensor210may be disposed of within one of the stop pads (to monitor the surface conditions of the other stop pad) or externally to the stop pads (to monitor the surface conditions of one or both stop pads).

When disposed internally to the stop pads, a cavity defined in the stop pad and/or the body of the associated shock strut holds the camera sensor210with its image capturing end facing outward. The shape and size of the camera sensor210relative to the cavity and/or an opening defined in the stop pad may capture the camera sensor210within the cavity so that the lens of the camera sensor210does not extend past the contacting surface of the stop pad that the camera sensor210is mounted within. To cushion the camera sensor210from impacts during aircraft operations (e.g., landing gear extension/retraction, takeoff, landing), one or more camera actuator members220, such as springs, pistons, micro linear actuators, or the like, are connected with the camera sensor210within its housing.

When disposed externally to the stop pads, such as in a space between stop pads, the camera sensor210may be held in a fixed mount or a rotating mount. An external mount for the camera sensor210may also include springs to cushion the camera from impacts. When employing a rotating mount, the second shock strut120may be communicated to the camera sensor210to co-rotate or counter-rotate the camera relative to the truck lever130as the truck lever130rotates between the extended and static positions to maintain or establish a field of view that includes the monitored contacting surfaces.

The computing device240to which the camera sensor210is connected includes computer readable memory storage devices (e.g., hard drives, RAM (Random Access Memory), flash drives) and processors that execute logic stored on the memory storage devices, which may control various components of the aircraft or interface to control or diagnose various features of the camera sensor210. For example, the computing device240may be the onboard computer for the aircraft or may be an external computer used by maintenance personnel that is connected to the camera sensor210during maintenance checks and/or pre-/post-flight checkups. The camera sensor210may also include computer readable memory storage devices and processors to control its capture and/or analysis of images, or may rely on the computing device240for control and/or storage.

In some embodiments, the camera sensor210stores one or more images captured during takeoff and/or landing (when the contact surfaces are visible) in an internal memory storage device or a memory storage device of the computing device240. The camera sensor210may take images in response to a signal from the computer device240indicating that the second shock strut120is moving the levered landing gear100into or out of the extended position, a timing signal (e.g., every X seconds, Y seconds after an event), or a signal from another sensor indicating that a non-conformance has been detected by that sensor.

The captured images may be retained for human inspection, or compared by the computing device240against a nominal state of the contact surface to generate alerts when a non-conformance is visually detected. For example, maintenance personnel may manually check the captured images to determine whether maintenance should be performed on the levered landing gear100. In another example, an artificial intelligence (AI) or computer learning algorithm may be employed by the computing device240to learn when a human or another sensor would indicate a non-conformance, and generate alerts based on the learned visual appearances of non-conformances. In a further example, various image thresholds may be used against the captured images, such as, for example, a color or albedo threshold for the image that indicates a percentage of the image that must be within a predetermined range of a nominal color or albedo to alert when a patina has been removed (e.g., via a scratch or pitting revealing a differently colored/reflective substrate), a contaminant/debris has been introduced (e.g., replacing the expected color or reflectiveness with the contaminant's color/reflectiveness), or corrosion is occurring.

FIG.3illustrates a detailed view300of a gap sensor310integrated in an example levered landing gear100according to an embodiment of the present disclosure. AlthoughFIG.3illustrates one gap sensor310integrated in the strut pad160and the first shock strut110, it will be appreciated that a gap sensor310may also be integrated in the truck pad170and the truck lever130, and that more than one gap sensor310may be employed in an array. When employed in an array, each gap sensor310of the array may measure a localized portion of the gap distance181in the stop joint180or may be combined to measure the gap distance181as an average across several locations.

In various embodiments, the gap sensor310includes one or more of an eddy current sensor or a range finder to determine a gap distance181in the stop joint180between the gap sensor310and the opposing stop pad's contact surface. The gap sensor310is disposed of within the stop pad and surrounding substrate via a bushing320at a calibrated distance from an opposing stop pad, and communicated with the computing device240via a gap cable330. The bushing320and an associated locking nut340hold the gap sensor310in a stable position relative to the nominal position of the contact surfaces so that as the stop pads wear or erode, or as cracks or debris are introduced that alter the measured gap distance181, the change will be noted.

For example, when a through-hole in the strut pad160includes a gap sensor310, the distance from the measurement point of the gap sensor310and the truck pad170(i.e., the opposing stop pad in this example) is calibrated for the nominal gap distance181when the stop pads form the stop joint180. The measured distances between the gap sensor310and the truck pad170are compared against a gap threshold, either by the gap sensor310or the computing device240to which the gap sensor310communicates its measurements, so that an alert is generated when the distance of the gap distance satisfies the gap threshold. In various embodiments, the gap threshold specifies a range (positive and negative relative to the nominal gap distance) that the gap distance may vary before an alert is generated.

When the gap sensor310is an eddy current sensor or other inductive sensor, an alternating current energizes the gap sensor310, which induces eddy current into the surrounding materials of one or more of the stop pads. These eddy currents, in turn, affect an impedance within the gap sensor310that is measured to determine a corresponding gap distance181between the gap sensor310and the opposing contact surface.

When the gap sensor310is a range finder, the gap sensor310generates a ranging signal when activated, and measures a time for the ranging signal to be reflected back to the range finder. Examples of range finders include laser range finders and acoustic range finders (e.g., sonar, ultrasound) to determine the return times of the ranging signal (e.g., a laser or soundwave) through the speed of the ranging signal through the material forming the gap (e.g., air).

As will be appreciated, as material expand and contract due to changes in temperature, the temperature of the stop pads and the gap sensor310may affect the measured gap distance. In various embodiments, the computing device240will apply a temperature offset to the measured distances reported by the gap sensor310or alter the gap threshold to account for changes in temperature that will affect proper alerting (reducing false positives and false negatives). In other aspects, the gap sensor310includes temperature compensations so that as the temperature of the gap sensor310and stop pads change, the reported change in gap distance181will be compensated for.

FIG.4illustrates a detailed view400of a thickness sensor410integrated in an example levered landing gear100according to embodiments of the present disclosure. AlthoughFIG.4illustrates one camera sensor210integrated in the truck pad170and the truck lever130, it will be appreciated that a thickness sensor410may also be integrated in the strut pad160and the first shock strut110, and that more than one thickness sensor410may be employed in an array. When employed in an array, each thickness sensor410may measure a localized portion of an associated stop pad or may be combined to measure the thickness as an average across several locations.

In some embodiments, the thickness sensor410is an ultrasound sensor that measures the thickness of the associated stop pad by generating ultrasonic sound waves that are transmitted into the mounted surface of the stop pad and measuring a time that it takes for the sound waves to reflect from the contact surface back to the thickness sensor410.

The thickness sensor410is disposed internally to the stop pads, in a cavity defined in the body of the truck lever130when associated with the truck pad170or in the body of the first shock strut110when associated with the strut pad160. The thickness sensor410is held in contact with the stop pad via a thickness actuator member420, such as a spring, piston, micro linear actuator, or the like, which also serves to cushion the thickness sensor410from impacts during aircraft operations (e.g., landing gear extension/retraction, takeoff, landing). Measurements of the pad thickness are transmitted to the computing device240via the thickness cable430, which may also supply power for the thickness sensor410.

For example, when the truck pad170includes a thickness sensor410, the thickness sensor410is calibrated for the nominal pad thickness173. As the truck pad170is used, wear and tear on the pad will erode the thickness thereof. Additionally, if any cracks or pitting develop in the truck pad170, the localized thickness will be lowered from the nominal pad thickness173. Moreover, if the truck pad170is overly compressed or develops a patina, localized portions of the truck pad170may exceed the nominal pad thickness173. The measured pad thicknesses173are compared against a thickness threshold, either by the thickness sensor410or the computing device240to which the thickness sensor410communicates its measurements, so that an alert is generated when the pad thickness satisfies the thickness threshold. In various embodiments, the thickness threshold specifies a range (positive and negative relative to the nominal gap distance) that the pad thickness may vary before an alert is generated.

For example, when employed to measure the thickness of the truck pad170, the thickness sensor410is held in contact with the second mounted surface172of the truck pad170by the thickness actuator member420. The thickness sensor410measures a pad thickness173of the truck pad170, defined by the distance between the mounted surface172and the contact surface171.

The thickness sensor410may measure the pad thickness when the levered landing gear100is in the extended position or on the static position. As will be appreciated, as the temperature of the truck pad170(or the strut pad160if a thickness sensor410is employed therewith) changes, the thickness or the acoustic properties (e.g. the speed at which sound travels through the material) of the stop pad may change. In various embodiments, the computing device240will apply a temperature offset to the measured pad thickness reported by the thickness sensor410or alter the thickness threshold to account for changes in temperature that will affect proper alerting (reducing false positives and false negatives). In other aspects, the thickness sensor410includes temperature compensations so that as the temperature of the thickness sensor410and stop pads change, the reported change in pad thickness will be compensated for when reported to the computing device240.

FIG.5illustrates an example deployment500of a single camera sensor210and multiple gap sensors310integrated in an example levered landing gear100according to an embodiment of the present disclosure. As will be appreciated, the example deployment500is provided as a non-limiting example of the present disclosure, and embodiments with more, fewer, or different components that may be arranged in different positions are contemplated.

In the example deployment500, a first gap sensor310aand a second gap sensor310bare disposed of in a first strut pad160aand a second strut pad160b, respectively. The first gap sensor310ameasures a distance to a first truck pad170aas a first gap distance181a, and the second gap sensor310bmeasures a distance to a second truck pad170bas a second gap distance181b. As will be appreciated, each of the first strut pad160a, the second strut pad160b, the first truck pad170a, and the second truck pad170bmay be individual stop pads that are separately replaceable, or may be localized portions of a single respective strut pad160or truck pad170.

Both the first gap sensor310aand the second gap sensor310bare communicated to a computing device240via a respective first gap cable330aand a second gap cable330b. The computing device240receives the measured gap distances181from the gap sensors310, and may compare the measured gap distances181individually or collectively against one or more gap thresholds. For example, the computing device240may average the readings received from the several gaps sensors310for comparison against an average gap threshold and also compare the individual readings received from specific gap sensors310against localized gap thresholds.

In addition to the gap sensors310, a camera sensor210is included in the example deployment500, which faces the truck pads170and is connected with the computing device240via a camera cable230. In various embodiments the camera sensor210is disposed of within the strut pad160, between individual strut pads160(e.g., a first strut pad160aand a second strut pad160b), or on the first shock strut110separately from the stop pads. The camera sensor210may include a wide angle lens to focus on both truck pads170simultaneously, a movable lens to focus on the first truck pad170aand the second truck pad170bat different times.

The computing device240may signal one or more of the sensors to take measurements at specific times, in response to specific conditions, or may sample measurements when specific conditions are true. For example, the computing device240may signal the gap sensors310to take readings of the gap distances181when the levered landing gear100enters the static position and every X seconds thereafter. In another example, the computing device240may signal the camera sensor210to capture images in response to the gap sensors310indicating a gap distance181that is out of conformance once the levered landing gear100transitions to an extended position. In a further example, the gap sensors310may take constant measurements, and the computing device240may ignore or discard data while the levered landing gear100is in the extended position. In another example, the camera sensor210captures several images while the levered landing gear100is in the extended position, and the computing device240determines whether to retain those images based on whether the gap sensors310indicate that the gap distance181is out of conformance when the levered landing gear100next returns to the static position.

FIG.6illustrates an example deployment600of a single camera sensor210and multiple thickness sensors410integrated in an example levered landing gear100according to an embodiment of the present disclosure. As will be appreciated, the example deployment600is provided as a non-limiting example of the present disclosure, and embodiments with more, fewer, or different components that may be arranged in different positions are contemplated.

In the example deployment600, a first thickness sensor410aand a second thickness sensor410bare disposed of in a first truck pad170aand a second truck pad170b, respectively. The first thickness sensor410ameasures a thickness of the first truck pad170aas a first pad thickness distance173a, and the second thickness sensor410bmeasures a thickness of a second truck pad170bas a second thickness173b. As will be appreciated, each of the first strut pad160a, the second strut pad160b, the first truck pad170a, and the second truck pad170bmay be individual stop pads that are separately replaceable, or may be localized portions of a single respective strut pad160or truck pad170.

Both the first thickness sensor410aand the second thickness sensor410bare communicated to a computing device240via a respective first thickness cable430aand a second thickness cable430b. The computing device240receives the measured thicknesses distances173from the thickness sensors410, and may compare the measured thicknesses173individually or collectively against one or more thickness thresholds. For example, the computing device240may average the readings received from the several thickness sensors410for comparison against an average thickness threshold and also compare the individual readings received from specific thickness sensors410against localized thickness thresholds.

In addition to the thickness sensors410, a camera sensor210is included in the example deployment600, which faces the truck pads170and is connected with the computing device240via a camera cable230. In various embodiments the camera sensor210is disposed of within the strut pad160, between individual strut pads160(e.g., a first strut pad160aand a second strut pad160b), or on the first shock strut110separately from the stop pads. The camera sensor210may include a wide angle lens to focus on both truck pads170simultaneously, a movable lens to focus on the first truck pad170aand the second truck pad170bat different times.

The computing device240may signal one or more of the sensors to take measurements at specific times, in response to specific conditions, or may sample measurements when specific conditions are true. For example, the computing device240may signal the thickness sensors410to take readings of the thicknesses173every X seconds. In another example, the computing device240may signal the camera sensor210to capture images in response to the thickness sensors410indicating a thickness173that is out of conformance once the levered landing gear100transitions to an extended position. In a further example, the thickness sensors410may take constant measurements, and the computing device240may sample those measurements every X seconds. In another example, the camera sensor210captures several images while the levered landing gear100is in the extended position, and the computing device240determines whether to retain those images based on whether the thickness sensors410indicate that the thickness173is out of conformance.

FIG.7illustrates an example deployment700of multiple camera sensors210and multiple thickness sensors410integrated in an example levered landing gear100according to an embodiment of the present disclosure. As will be appreciated, the example deployment700is provided as a non-limiting example of the present disclosure, and embodiments with more, fewer, or different components that may be arranged in different positions are contemplated.

In the example deployment700, a first thickness sensor410aand a second thickness sensor410bare disposed of in a first truck pad170aand a second truck pad170b, respectively. The first thickness sensor410ameasures a thickness of the first truck pad170aas a first pad thickness distance173a, and the second thickness sensor410bmeasures a thickness of a second truck pad170bas a second thickness173b. As will be appreciated, each of the first strut pad160a, the second strut pad160b, the first truck pad170a, and the second truck pad170bmay be individual stop pads that are separately replaceable, or may be localized portions of a single respective strut pad160or truck pad170.

Both the first thickness sensor410aand the second thickness sensor410bare communicated to a computing device240via a respective first thickness cable430aand a second thickness cable430b. The computing device240receives the measured thicknesses distances173from the thickness sensors410, and may compare the measured thicknesses173individually or collectively against one or more thickness thresholds. For example, the computing device240may average the readings received from the several thickness sensors410for comparison against an average thickness threshold and also compare the individual readings received from specific thickness sensors410against localized thickness thresholds.

In addition to the thickness sensors410, a first camera sensor210aand a second camera sensor210bare included in the example deployment700, which faces the truck pads170and are connected with the computing device240via a first camera cable230aand a second camera cable230b, respectively. Each of the camera sensors210are disposed of in a respective first strut pad160aand a second strut pad160band each camera sensor210may include a wide angle lens to focus on both truck pads170simultaneously, a movable lens to focus on the first truck pad170aand the second truck pad170bat different times, or may be focused on an individual truck pad170. In embodiments where each camera sensor210is focused on both truck pads170, the computing device may combine the received images to create a 3D composite view of the contact surfaces171of the truck pads170.

The computing device240may signal one or more of the sensors to take measurements at specific times, in response to specific conditions, or may sample measurements when specific conditions are true. For example, the computing device240may signal the thickness sensors410to take readings of the thicknesses173every X seconds. In another example, the computing device240may signal the camera sensor210to capture images in response to the thickness sensors410indicating a thickness173that is out of conformance once the levered landing gear100transitions to an extended position. In a further example, the thickness sensors410may take constant measurements, and the computing device240may sample those measurements every X seconds. In another example, the camera sensor210captures several images while the levered landing gear100is in the extended position, and the computing device240determines whether to retain those images based on whether the thickness sensors410indicate that the thickness173is out of conformance.

FIG.8is a flowchart illustrating the general steps in an example method800for providing health monitoring of aircraft landing gear mechanical structures according to embodiments of the present disclosure. Method800begins at block810, where one or more sensors are calibrated for the nominal stop pad conditions that they are designed to monitor. For example, when one or more stop pads are newly installed (replacing prior stop pads or at an initial installation) one or more of a camera sensor210, gap sensor310, and thickness sensor410are calibrated for an initial color/appearance, gap distance181, and/or pad thickness. Calibration may involve adjusting the measurements produced by the sensors to match the nominal values, training a machine learning algorithm to detect aberrant conditions based on a supervised set of measurement data (e.g., prior known conforming and non-conforming measurements), and adjusting the various thresholds that the measured values are compared against.

At block820the stop pads are monitored by the calibrated sensors. In various embodiments, the sensors may periodically (e.g., every X seconds) take measurements of the stop pads, may take measurements in response to a user request for the signal, take measurements in response to a transition to or from the extended position, or may take measurements constantly. The camera sensors210(if included) capture images that are compared against nominal or initial image feature thresholds when the levered landing gear100is not in the static position. The gap sensors310(if included) take measurements of the gap distance181when the levered landing gear100is in the static position. The thickness sensors410(if included) take measurements of the thickness of an associated stop pad regardless of the position of the levered landing gear100. As will be appreciated, the various measurements taken at block820may be measured across a period of time for a given sensor, across an array of sensors of a given type, or cross correlated between sensors/arrays of sensors of different types. For example, an image taken during landing by a camera sensor210may be correlated with the gap measurements taken by an array of gap sensors310prior to landing and/or after landing when the levered landing gear100is again in the static position.

Proceeding to block830, it is determined, based on the measurements and the associated thresholds, whether a non-conformance in the stop joint180has been detected. A non-conformance is determined to have been detected in response to a measurement from a sensor satisfying an associated threshold. For example, a thickness measured above an upper thickness threshold or measured below a lower thickness threshold may be determined to satisfy a thickness threshold. In another example, gap distance measured above an upper gap threshold or measured below a lower gap threshold may be determined to satisfy a gap threshold. In a further example, a color or albedo of a captured image is compared against a color or albedo threshold, and an image that has a calculated color or albedo outside of the color or albedo threshold is determined to satisfy that threshold. In an additional example, a confidence of an image recognition system (using a calibrated AI or a machine learning algorithm) that a non-conformance such as debris or damage to the contact surfaces is present is compared against a confidence threshold such that when the confidence exceeds the confidence threshold it is determined that the threshold has been satisfied.

In response to determining that a non-conformance has not been detected, method800returns to block820. In response to determining that a non-conformance has been detected, method800optionally proceeds to block840and then to block850. In some embodiments, method800continues performing blocks820and830once a non-conformance has been detected to determine whether the non-conformance is transient, spreading, or can be verified by additional sensors.

Optionally, at block840, camera sensor210is used to corroborate the detected non-conformance. As will be appreciated, method800may forego block840in embodiments that do not include a camera sensor210or when the non-conformance is detected after the levered landing gear100has entered the static position. The camera sensor210is signaled to capture an image of the stop pads that is associated with the detected non-conformance so that maintenance personnel may verify the presence of the indicated non-conformance and/or so that an image recognition system may be trained to identify non-conformances from images of the contact surfaces. The captured image is then stored in the camera sensor210and/or the computing device240for retrieval to corroborate the determination that the non-conformance has been detected.

At block850an alert is generated in response to the detected non-conformance. In various embodiments, the alert is generated and/or displayed by the computing device240. When block840is performed, the alert may be displayed along with the image of the detected non-conformance or in response to maintenance personnel or an operator of the aircraft acknowledging the alert (e.g., via an operating system response to the alert, an alert silence button, an alert clear signal, or the like).

Method800may then conclude.

Several examples and embodiments of the apparatus and methods are disclosed herein that include a variety of components, features, and functionalities. It will be understood that the various examples and embodiments of the apparatus and methods disclosed in the present disclosure may include any of the components, features, and functionalities of any of the other examples and embodiments of the apparatus and methods disclosed in the present disclosure in any combination, and all of such possibilities are intended to be within the spirit and scope of the present disclosure.

Having the benefit of the teachings presented in the foregoing description and the associated drawings, many modifications of the disclosed subject matter will become apparent to one skilled in the art to which this disclosure pertains. Therefore, it is to be understood that the disclosure is not to be limited to the specific examples and embodiments provided and that modifications thereof are intended to be within the scope of the appended claims. Moreover, although the foregoing disclosure and the associated drawings describe certain illustrative combinations of elements and/or functions, it will be appreciated that different combinations of elements and/or functions may be realized without departing from the scope of the appended claims.