Brake characteristics

Abstract

A non-transitory computer-readable storage medium having instructions stored thereon is disclosed, the instructions, when executed by a processor, causing the processor to perform the following operations: determining whether an aircraft wheel brake is capable of performing a future rejected takeoff event. The determination includes determining whether an estimated mass of the brake is sufficient to perform the future rejected takeoff event based on a rejected takeoff energy parameter and a brake parameter set. In addition, a method for determining whether an aircraft wheel brake is capable of performing a future rejected takeoff event is disclosed.

Description

Technical Field

[0001] The present invention relates to determining whether an aircraft wheel brake is capable of executing a future rejected take-off event. Background Art

[0002] The wheel brakes of an aircraft are subject to wear and oxidation. The amount of wear on the brakes can be checked and the brakes can be visually inspected to identify signs of oxidation. If the amount of wear and / or oxidation has reached a certain level, it can be considered that the brakes need repair or replacement. In this case, the aircraft in question may not be approved for flight. Summary of the invention

[0003] A first aspect of the present invention provides a non-transitory computer-readable storage medium having instructions stored thereon, which, when executed by a processor, causes the processor to perform the following operations: determining whether an aircraft wheel brake is capable of performing a future rejected takeoff event, including determining whether an estimated mass of the brake is sufficient to perform the future rejected takeoff event based on a rejected takeoff energy parameter and a brake parameter set.

[0004] Optionally, the instructions, when executed by a processor, cause the processor to perform the following operations: determine a number of estimated future usage cycles after which the estimated quality is expected to be insufficient to perform a future rejected takeoff event.

[0005] Optionally, the instructions, when executed by a processor, cause the processor to: determine a mass limit defining a minimum mass required to perform a future rejected takeoff event.

[0006] Optionally, the instructions, when executed by a processor, cause the processor to determine whether the estimated mass is sufficient to perform a future rejected takeoff event by comparing the estimated mass to a mass limit.

[0007] Optionally, the instructions, when executed by a processor, cause the processor to determine the mass limit using an amount of energy to be absorbed by the brakes when performing a future rejected takeoff event determined based on characteristics of the brakes.

[0008] Optionally, the instructions, when executed by a processor, cause the processor to: determine an estimated number of future usage cycles for the estimated quality to decrease to a quality limit.

[0009] Optionally, the instructions, when executed by a processor, cause the processor to perform the following operations: if it is determined that the estimated quality is sufficient to perform a future rejected takeoff event, issuing a first notification.

[0010] Optionally, the instructions, when executed by a processor, cause the processor to perform the following operations: if it is determined that the estimated mass is insufficient to perform a future rejected takeoff event, repeating the determination of whether the brakes are capable of performing a future rejected takeoff event.

[0011] Optionally, the determination is repeated using an updated rejected takeoff energy parameter determined based on the updated aircraft weight.

[0012] Optionally, the instructions, when executed by a processor, cause the processor to: in response to the updated aircraft weight satisfying the aircraft weight criteria, issue a second notification indicating that the brakes require maintenance or replacement, and cease repeating the determination.

[0013] Optionally, the instructions, when executed by a processor, cause the processor to perform the following operations: determine a rejected takeoff energy parameter based on a set of user input parameters.

[0014] Optionally, the brake parameter set includes an upper temperature cutoff for the brakes.

[0015] Optionally, the instructions, when executed by the processor, cause the processor to determine a temperature limit, the temperature limit being a maximum temperature that the brakes are expected to reach when a future rejected takeoff event occurs.

[0016] Optionally, the instructions, when executed by the processor, cause the processor to determine whether an estimated quality of the brakes is sufficient to perform a future rejected takeoff event by comparing the temperature limit to an upper temperature cutoff of the brakes.

[0017] A second aspect of the invention provides a method comprising: determining whether an aircraft wheel brake is capable of executing a future rejected takeoff event, including determining whether an estimated mass of the brake is sufficient to execute the future rejected takeoff event based on a rejected takeoff energy parameter and a brake parameter set.

[0018] Optionally, the method according to the second aspect comprises determining a number of estimated future usage cycles after which it is expected that the estimated quality will be insufficient to perform a future rejected takeoff event.

[0019] A third aspect of the present invention provides an apparatus comprising a processor configured to determine whether an aircraft wheel brake is capable of executing a future rejected takeoff event, including determining whether an estimated mass of the brake is sufficient to execute the future rejected takeoff event based on a rejected takeoff energy parameter and a brake parameter set. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0021] Figure 1 is a schematic diagram of an aircraft upon which examples of the present invention may be deployed;

[0022] Figure 2 is a schematic diagram of a wheel of an aircraft landing gear and an aircraft wheel brake according to an example;

[0023] Figure 3 is a first flow chart of a first exemplary method of determining whether an aircraft wheel brake is capable of executing a future rejected takeoff event;

[0024] Figure 4a a second flow chart of a portion of a second exemplary method of determining whether an aircraft wheel brake is capable of executing a future rejected takeoff event;

[0025] Figure 4b is a third flow chart of a portion of a second exemplary method of determining whether an aircraft wheel brake is capable of executing a future rejected takeoff event;

[0026] Figure 5 is a schematic diagram of an exemplary computing device for executing the method of the present invention.

[0027] Figure 6 is a diagram showing, according to an example, the condition of an aircraft wheel brake according to the number of use cycles of the brake;

[0028] Figure 7 is a flow chart of an exemplary method of determining a thermal oxidation state of a brake of an aircraft landing gear;

[0029] Figure 8 is a flow chart of an exemplary method of determining a thermal oxidation state of a brake of an aircraft landing gear;

[0030] Fig. 9 is an exemplary graph showing temperature of a brake with respect to time;

[0031] Fig.10 is an exemplary graph showing thermal oxidation status of a brake with respect to time at a specific temperature;

[0032] Fig.11 is an exemplary flow chart of a method of determining brake wear according to an example; and

[0033] Fig.12 is an exemplary flow chart of a method for estimating a number of good future usage cycles for aircraft brakes according to an example. DETAILED DESCRIPTION

[0034] Figure 11 is a simplified schematic diagram of an aircraft 100. Aircraft 100 includes a plurality of landing gear assemblies 102. Landing gear assemblies 102 may include main and nose landing gear that may be extended during takeoff and landing. Each landing gear assembly 102 includes a wheel such as wheel 104. Aircraft 100 also includes a computing system 106 that includes one or more processors and one or more computer-readable storage media. Aircraft 100 also includes a set of sensors 108 that may include sensors for measuring environmental characteristics and sensors associated with various components of aircraft 100 and measuring values ​​of various physical properties of the corresponding components. Although in Figure 1 The sensor 108 is represented by a single box in the schematic diagram of FIG. 1 , but it will be understood that the sensor 108 can be located at a variety of different locations on the aircraft 100. The aircraft 100 can also include a set of indicator devices 110 for providing various indications related to the aircraft 100 and environmental conditions. The indicator device can include a screen that displays text and / or graphics, a dial, a light indicator, a sound indicator that emits a sound that provides an indication, etc. The indicator device can be inside or outside the aircraft 100.

[0035] Figure 2 1 is a simplified schematic diagram of an aircraft wheel brake 200 (hereinafter referred to as "brake" 200) associated with a wheel 104 of an aircraft 100. Each wheel of the aircraft 100 may have a brake associated therewith, such as brake 200. Brake 200 applies a braking force to inhibit rotation of wheel 104. In this example, brake 200 includes a plurality of brake discs 202, brake discs 202 including pressure plates 204, reaction plates 206, and a number of rotors and stators, such as rotor 208 and stator 210. In this example, brake discs 202 include a plurality of rotors and stators, so brake assembly 200 is a multi-disc brake. In other examples, brake assembly 200 may not be a multi-disc brake. It should be understood that the type of brake used in an aircraft landing gear depends on the characteristics of the aircraft in question, such as size, load carrying capacity, etc.

[0036] When the aircraft 100 travels along the ground supported by the landing gear 102, the rotor rotates with the wheel 104, while the stator, the pressure plate 204 and the reaction plate 206 do not rotate with the wheel 104. When the brakes are applied, the pressure plate 204 is pushed toward the reaction plate 206, causing the brake discs 202 to contact each other (e.g., Figure 2 212), and friction acts to inhibit the rotational motion of the rotor, thereby generating a braking force to reduce the speed of the aircraft 100. The brake 200 may be hydraulically actuated or electrically actuated.

[0037] Any one or more of the rotor, stator, pressure plate 204, and reaction plate 206 may be constructed of a carbon-carbon (CC) composite. A brake comprising a brake disc constructed of a CC composite may be referred to as a carbon brake. For example, the brake disc 202 may be constructed of a graphite matrix reinforced with carbon fibers.

[0038] The brake 200 may be provided with a brake wear sensor 216 (described in further detail below). The brake 200 may also be provided with a temperature sensor 218. The temperature sensor 218 may be provided in thermal contact with one of the brake discs. Figure 2 In an example of the invention, the temperature sensor 218 is disposed on the stator 210. In this example, the stator 210 is the brake disc that may reach the highest temperature. The temperature sensor 218 may be any type of temperature sensor suitable for use in an aircraft brake assembly. For example, the temperature sensor 218 may operate normally within the temperature range that the brake disc 202 may reach. For example, the temperature sensor 218 may be a thermocouple, a surface acoustic wave (SAW) sensor, an eddy current sensor, a resistive thermal sensor, a strain gauge, etc. If a temperature sensor is disposed on a portion of the brake 200 other than one of the brake discs 202, an indication of a relationship between the temperature measured by the temperature sensor and the temperature of the brake disc 202 may be used to determine the temperature of the brake disc 202. In some examples, the relationship indication may be determined by experiment. In some examples, the relationship indication may be determined using a brake thermal model.

[0039] During use, the brake disc 202 may undergo oxidation. During the oxidation reaction, oxygen reacts with the carbon of the brake disc 202, causing carbon atoms to be removed from the brake disc 202 along with the production of carbon dioxide and / or carbon monoxide, thereby causing a mass loss per unit volume of the disc brake 202. The oxidation state / level of the brake 200 can be expressed as the amount of mass lost due to oxidation.

[0040] The brake disc 202 may be oxidized via catalytic oxidation or thermal oxidation. Catalytic oxidation may occur when the oxidation reaction is aided by the action of a catalyst. For example, alkali metals are known catalysts for oxidation of CC compounds. Catalytic oxidation may be involved in areas with relatively high salinity to the air. Catalytic oxidation may also be involved at airports where runway de-icers including alkali metal salts are used. Thermal oxidation of the brake disc 202 may occur if the brake disc 202 reaches a high temperature during use due to friction. This is because when the brake 200 is applied to reduce the speed of the aircraft 100, some of the kinetic energy of the aircraft 100 is absorbed into the brake 200 as heat that increases its temperature. In this example, the component of the brake 200 (i.e., the brake disc 202) composed of the CC compound undergoes oxidation. However, hereinafter the present disclosure only refers to the oxidation state of the brake 200.

[0041] In addition, the brake disc 202 may experience wear due to friction during braking. For example, when a given brake disc contacts other brake discs, material may be lost from the surface of the given brake disc due to the friction during braking. Wear may cause the length L (in Figure 2 The wear state of the brake 200 may be determined using a measured wear value. The measured wear value may be a measured length associated with the brake 200. For example, the measured wear value may be the length L of the brake disc 202 or a length from which the length L may be derived. The measured wear value provides an indication of a change in the length L and therefore an indication of the amount of wear on the brake. Therefore, wear may be represented as a decrease in the length of the brake disc 202. Therefore, wear and oxidation may cause a decrease in the mass of the brake 200. In this example, the brake disc 202 is worn. However, the present disclosure hereinafter refers only to the wear state of the brake 200.

[0042] Due to use, the condition of the brake disc 202 may deteriorate over time. A pre-flight inspection may be performed to check various aspects of the aircraft 100 to ensure safe flight. The inspection may be performed in a variety of different ways. For example, a pilot of the aircraft 100 may obtain various indications related to the aircraft before the flight (e.g., using a computer system). For example, a ground crew may perform a pre-flight inspection before the flight. The condition of the brakes of the aircraft 100, such as the brake 200, may be inspected. In an example of the prior art, the brake 200 may be visually inspected to identify signs of oxidation, and an indication of the amount of brake wear may be obtained (e.g., by inspecting a wear pin as described below). Oxidation and brake wear will be discussed in further detail below.

[0043] If the condition of brake 200 is found to have degraded beyond a certain level (e.g., a given amount of brake wear is indicated, and or oxidation becomes visually evident), then brake 200 may be deemed to require maintenance, or replacement of the entire brake 200 or a portion thereof. As a result, aircraft 100 may not be permitted to commence flight until the maintenance or replacement is performed.

[0044] A brake wear threshold may be specified for the brake 200. For example, the brake wear threshold may be specified by the manufacturer of the brake 200. The brake wear threshold may be related to the value of the length L of the brake disc 202. When the length L is reduced to the brake wear threshold, it may be considered that the brake 200 needs to be repaired or replaced. The brake wear threshold may be a conservative threshold based on operating conditions under a worst-case scenario. However, even when the length L has reached the brake wear threshold, the brake disc 202 may not be completely worn. For example, depending on operating conditions, the brake disc 202 may have a sufficient length, and the brake 200 may have sufficient mass for safe use. For example, despite reaching the brake wear threshold, the brake 200 may still be able to be safely used for any potential braking application under current operating conditions. In such an example, it may not be necessary to perform the maintenance of the brake 200 discussed before the flight.

[0045] For example, the brake 200 may be able to perform a future rejected takeoff event for certain operating conditions. A rejected takeoff event requires severe braking to abort takeoff and can be performed at high speeds. If the brake 200 is able to perform a rejected takeoff event, it can be considered safe for use. In the following example, a future rejected takeoff event involves aborting the takeoff at a speed known as the decision speed (V1). The rules require that the aircraft be able to perform a rejected takeoff at any time before reaching the speed V1 for the aircraft and stop before the end of the runway. Above the V1 speed, takeoff should no longer be aborted (e.g., even if an engine fails or another problem occurs). This is because, for example, a rejected takeoff event performed beyond V1 may cause the aircraft 100 to overrun the runway and cause and / or suffer serious damage.

[0046] The amount of brake wear and oxidation affects the mass of the brake disc 202 that is experiencing the oxidation and wear. However, only reference will be made to the mass of the brake 200 in the following. The mass of the brake 200 may affect its performance. Despite the loss of mass by reaching a specified brake wear threshold, the brake 200 may have sufficient mass to be safely used under given operating conditions. For example, the brake 200 may have sufficient mass to perform a future rejected takeoff event.

[0047] Figure 33 is a flow chart of method 300. A non-transitory computer readable storage medium (hereinafter referred to as storage medium) having instructions stored thereon may be provided, the instructions, when executed by a processor, causing the processor to perform method 300. Method 300 is for determining whether brake 200 is capable of performing a future rejected takeoff event. At block 302, it is determined whether an estimated mass of brake 200 is sufficient to perform a future rejected takeoff event based on a rejected takeoff energy parameter and a brake parameter set.

[0048] The rejected takeoff energy parameter may indicate the amount of kinetic energy that the aircraft 100 will need to lose to execute a future rejected takeoff event. As discussed, a future rejected takeoff event is a rejected takeoff when the aircraft 100 is moving at a speed V1. The V1 speed of the aircraft 100 may depend on the performance characteristics of the aircraft 100, environmental conditions, the length of the runway, and the weight of the aircraft 100, which are examples of operating conditions. The performance characteristics of the aircraft 100 may include thrust settings, pull-up speed (which is defined as the speed at which the pilot can begin to apply control inputs to get the aircraft nose up and then off the ground), etc. Environmental conditions may include conditions such as altitude, temperature, wind force and direction, specific characteristics of the runway in question, and precipitation levels.

[0049] The brake parameter set may include an upper temperature cutoff for the brake 200. The upper temperature cutoff may be a temperature at which the performance of the brake 200 degrades, a temperature at which a fuse of the corresponding wheel 104 melts to relieve pressure, a temperature at which the brake disc 202 undergoes thermal oxidation, a temperature at which the corresponding shaft suffers thermal damage, etc. It may be desirable that the temperature of the brake 200 does not exceed the upper temperature cutoff. The brake parameter set may also include parameters indicating physical properties of the brake 200. For example, the brake parameter set may include a specific heat capacity of the brake 200. The specific heat capacity of the brake 200 may be a function of certain variables such as temperature.

[0050] The estimated mass of the brake 200 may be the estimated current mass of the brake 200 or the estimated future mass of the brake 200. In an example where the future rejected takeoff event is a rejected takeoff event that may potentially occur during the next flight, the estimated current mass of the brake 200 may be used. In an example where the future rejected takeoff event is a rejected takeoff event that may potentially occur after a number of future flights have occurred, the estimated future mass of the brake 200 may be used. The estimated future mass of the brake may be determined based on the estimated current mass.

[0051] The estimated mass can be determined based on the estimated oxidation state of the brake 200 and the wear state of the brake 200. As discussed, oxidation and wear result in a loss of mass of the brake 200. The estimated oxidation state of the brake 200 can be expressed as the amount of mass lost from the brake 200 due to oxidation. As discussed, the wear state of the brake 200 can be expressed as a reduction in the length L of the brake disc 202. Given the density (which can take into account the oxidation level) and surface area of ​​the brake disc 202, the amount of mass lost due to brake wear can be determined based on the reduction in length. The amount of mass lost due to oxidation and the amount of mass lost due to wear can be subtracted from the original mass of the brake 200 (i.e., the mass of the brake 200 when it is new and unused) in order to estimate the mass of the brake 200.

[0052] In an example where the estimated current mass of the brake 200 is to be determined, the estimated current oxidation state and the current wear state may be used. In an example where the estimated future mass of the brake 200 is to be determined, the estimated future oxidation state and the estimated wear state may be used, the estimated wear state being the estimated future wear state. The manner in which the estimated current oxidation state and the estimated future oxidation state of the brake 200 may be determined will be described in further detail below. Additionally, the manner in which the wear state may be measured and the manner in which the future wear state may be estimated will be described in further detail below.

[0053] Further details of how to determine whether the estimated mass of the brakes is sufficient to perform a future rejected takeoff event are described below. Figure 4a and 4b is a flow chart of method 400 illustrating actions that may be performed as part of method 300. Method 400 also includes actions in addition to determining whether the estimated mass of the brake is sufficient to perform a future rejected takeoff event. Where feasible, the blocks of method 400 may be performed in a variety of different orders and / or certain blocks may be omitted, as long as it is determined whether brake 200 is capable of performing a rejected takeoff event. A non-transitory computer-readable storage medium may store instructions that, when executed by a processor, cause the processor to perform all or part of method 400.

[0054] At block 402 of method 400, a decision speed V1 is determined. As discussed, the V1 speed may depend on performance characteristics of the aircraft 100, environmental conditions, runway length, and weight of the aircraft 100 as examples of operating conditions. For example, a storage medium may store instructions that, when executed by a processor, cause the processor to use these factors to determine the V1 speed. Information about these factors may be received by the processor from sensors 108 of the aircraft 100, retrieved from a computer-readable storage medium, and / or input by a user of the processor.

[0055] In some examples, the V1 speed can be determined using the maximum takeoff weight, which can be the maximum weight that a specified aircraft 100 has when flying. In some examples, a measured aircraft weight (i.e., the actual current weight of the aircraft 100) can be used. In some examples, an estimated aircraft weight can be used. For example, the aircraft weight can be estimated by summing the known empty weight, fuel weight estimate, passenger and crew weight estimate, and luggage weight estimate of the aircraft 100. In some examples, the aircraft weight can be estimated by adding a certain proportion of the weight capacity of the aircraft (based on the number of passengers on the flight, etc.) to the known empty weight. In the following discussion, it is simply referred to as the aircraft weight. As will be described below, the method 400 can be repeated (in an iterative manner) using different operating conditions. In some examples, the method 400 can be performed using the measured (or estimated) aircraft weight, and the method 400 can be repeated using an updated aircraft weight value, which is an updated value input into the method 400 for the purpose of repeating the method 400.

[0056] At block 404, the rejected takeoff energy parameter may be determined based on the aircraft weight and speed V1. In some examples, the rejected takeoff energy parameter may be determined based on a set of user input parameters. For example, a user may input a set of parameters indicating one or more operating conditions based on which blocks 402 and 404 are performed. Thus, a user may perform the methods described herein for a variety of different operating conditions.

[0057] At 406 of method 400, a mass limit is determined, which defines the minimum mass required to perform a future rejected takeoff event (i.e., the minimum mass of the brake 200). The mass limit may be determined using the amount of energy that the brake 200 will absorb when performing a future rejected takeoff event. It should be noted that all brakes of the aircraft 100 applied during a future rejected takeoff event will absorb some kinetic energy of the aircraft 100. The mass limit is determined using the amount of energy that the particular brake for which method 400 is performed will absorb. Thus, the amount of energy that the brake 200 will absorb (i.e., the proportion of the total kinetic energy of the aircraft 100 that must be lost during the rejected takeoff event) is determined and used to determine the mass limit.

[0058] In some examples, the amount of energy that the brake 200 will absorb can be determined based on a gain characteristic of the brake 200. The gain characteristic of the brake 200 can indicate certain physical properties of the brake 200. For example, the gain characteristic can indicate the amount of energy that the brake 200 is expected to absorb for a given application force. Each brake of the aircraft 100 that can be applied during a future rejected takeoff event can have its own gain characteristic. The amount of energy that must be lost to stop the aircraft 100 during a future rejected takeoff event can be divided between the brakes to be applied taking into account the respective gain characteristics.

[0059] In the context of a future rejected takeoff event, the maximum force used to apply the brakes can be used. For example, given the maximum brake force, for the amount of time required for the aircraft 100 to stop, the amount of energy that each brake to be applied is expected to absorb can be considered. Therefore, the amount of total energy that the aircraft 100 must lose that will be absorbed by the brake 200 can be determined. The maximum force can depend on the force that can be provided by the hydraulic / electrical actuation system of the brake 200 when the pilot forcibly applies all brakes to perform a future rejected takeoff event. In some simpler examples, the total energy that the aircraft 100 must lose during the future rejected takeoff event (as indicated by the rejected takeoff energy parameter) can be divided according to the number of brakes of the aircraft 100 to be applied to estimate the amount of energy that will be absorbed by the brake 200 for which the method is performed. However, it should be noted that this method will not take into account the differences between the individual brakes. In some examples, when determining the energy to be absorbed by the brake 200, it can be assumed that there is a lack of braking on one of the wheels of the aircraft 100 (for example, to consider the worst-case scenario).

[0060] As discussed, the brake parameter set may include an upper temperature cutoff and a specific heat capacity of the brake 200. The mass limit of the brake 200 may be determined using the amount of energy that the brake 200 will absorb and the specific heat capacity of the brake 200 so that the brake 200 does not exceed the upper temperature cutoff. The mass limit may also take into account the physical size and density of the brake disc 202 (e.g., using an estimated oxidation state of the brake 200) so that the mass limit is related to a minimum size and density that will allow safe operation of the brake 200.

[0061] A temperature limit may be determined, which is the maximum temperature that the brake 200 is expected to reach when a future rejected takeoff event occurs. In the example of method 400, the temperature limit is determined at block 408. For example, the temperature may be determined using the amount of energy that the brake 200 will absorb, the estimated mass of the brake 200, and the specific heat capacity.

[0062] At block 410 , it is determined whether the estimated mass of the brake 200 is sufficient to perform a future rejected takeoff event.

[0063] In some examples, it may be determined whether the estimated mass is sufficient by comparing the estimated mass to a mass limit. For example, if the estimated mass is less than the mass limit, it may be determined that the estimated mass is insufficient to perform a future rejected takeoff event. On the other hand, if the estimated mass is greater than the mass limit, it may be determined that the estimated mass is sufficient to perform a future rejected takeoff event.

[0064] In some examples, it may be determined whether the estimated mass is sufficient by comparing the temperature limit to an upper temperature cutoff. For example, if the temperature limit is less than the upper temperature cutoff, it may be determined that the estimated mass is sufficient to perform a future rejected takeoff event (because the brakes 200 are not expected to get too hot). On the other hand, if the temperature limit is greater than the upper temperature cutoff, it may be determined that the estimated mass is insufficient to perform a future rejected takeoff event.

[0065] In an example where the future rejected takeoff event is a rejected takeoff event that may potentially occur during the next flight, the estimated mass used may be the estimated current mass of the brake 200 determined based on the estimated current oxidation state of the brake 200 and the current wear state of the brake 200. In an example where the future rejected takeoff event is a rejected takeoff event that may potentially occur after a given number of flights, the estimated future mass may be determined based on the estimated future oxidation state after the given number of flights and the estimated future wear state after the given number of flights.

[0066] Regardless of the outcome of this determination, the method proceeds to box 412. Box 412 is an optional box that may be executed and is described in further detail below. At box 412 of method 400, a number of estimated future use cycles of the brake 200 is determined, after which the estimated mass is expected to be insufficient to perform a future rejected takeoff event. The number of estimated future use cycles (after which the estimated mass is expected to be insufficient) is referred to below as the estimated brake mass cycle. A use cycle of the brake 200 may be the time from when the aircraft 100 on which the brake 200 is mounted is at the gate before the flight to when the aircraft 100 is at the arrival gate after the flight. For example, a use cycle includes all uses of the brake 200 associated with a corresponding flight undertaken by the aircraft 100. Thus, as used herein, a use cycle relates to a complete flight of the aircraft 100. An estimated future use cycle may be a use cycle of the brake 200 that has not yet occurred.

[0067] The estimated brake mass cycle can be determined by comparing the value of the estimated future mass to the mass limit. It should be noted that in the example where a future rejected takeoff event is associated with the next flight and the estimated current mass is determined to be insufficient, the estimated brake mass cycle is zero for the operating condition in question (e.g., aircraft weight). In the example, where a future rejected takeoff event is associated with the next flight and the estimated current mass is determined to be sufficient, the estimated brake mass cycle is at least one.

[0068] The values ​​of the estimated future mass of the brake 200 for each estimated future use cycle can be compared with the mass limit in sequence. For example, the estimated future mass for a first given estimated future use cycle can be compared with the mass limit. If the estimated future mass for the first given estimated future use cycle is greater than the mass limit, the estimated future mass for a second given estimated future use cycle can be compared with the mass limit. The second given estimated future use cycle can be the next cycle immediately after the first given estimated future use cycle. The comparisons can be continued in this manner in sequence until the estimated future mass for a particular estimated future use cycle is less than the mass limit. The estimated brake mass cycle can be determined as the number of estimated future use cycles that have not yet occurred, which is one less than the particular estimated future use cycle when the estimated future mass drops below the mass limit. In this way, an indication of when the brake 200 needs to be repaired or replaced can be provided. Advantageously, such a determination can allow maintenance and replacement work to be planned while avoiding flight delays caused by discovering problems with the brake 200 before the flight.

[0069] If it is determined that the estimated mass is sufficient to perform a future rejected takeoff event, a first notification may be issued. When the determination of block 410 is made using a prevailing operating condition, such as a measured aircraft weight, the first notification may indicate that the estimated mass is sufficient to perform a future rejected takeoff event for the prevailing operating condition (e.g., the measured aircraft weight). The content of the first notification may vary depending on the operating condition for which the determination of block 410 is made, as will be described below. In method 400, if it is determined that the estimated mass is sufficient, the method 400 proceeds to block 414. At block 414, the first notification is issued. If it is determined that the estimated mass is insufficient to perform a future rejected takeoff event, the determination of whether the brake 200 is capable of performing a future rejected takeoff event may be repeated. For example, the determination may be repeated using updated operating conditions. If it is determined at block 410 that the estimated mass is insufficient, the method 400 proceeds to block 416. At block 416, an updated value of the aircraft weight is input into the method for the purpose of repeating the determination of whether the brake is capable of performing a future rejected takeoff event. It should be noted that the updated value of the aircraft weight has nothing to do with the actual current weight of the aircraft 100, but is merely a value input into the method 400 for repeating the determination to check whether the brake 200 is capable of performing a future rejected takeoff event for different operating conditions (e.g., different aircraft weights). For example, the updated value may be lower than the measured (or estimated) aircraft weight. For example, the updated value may be a given amount lower than the measured (or estimated) aircraft weight. In some examples, the given amount may be the estimated weight of one passenger and their luggage. An example of the given amount is 100 kg. Each time the determination is repeated, the updated value of the aircraft weight input for the purpose of repeating the determination may be a given amount lower than the previous value. In this way, the determination may be iterated for various different values ​​of the aircraft weight.

[0070] In response to the updated value of the aircraft weight satisfying the aircraft weight criteria, a second notification indicating that the brake 200 needs to be repaired or replaced may be issued, and repetition of the determination may be stopped. In the example of method 400, at block 418, a determination is made as to whether the updated value of the aircraft weight satisfies the aircraft weight criteria. The aircraft weight criteria may simply be, for example, a lower aircraft weight limit below which it is undesirable and / or impossible to initiate flight.

[0071] If the aircraft weight criteria are met, the method 400 proceeds to block 402. Thus, if the estimated mass is determined to be insufficient using different operating conditions (in this case, an updated value of the aircraft weight), the determination is repeated. When block 402 is repeated, the decision speed V1 is determined based on the updated value of the aircraft weight. Similarly, when block 404 is repeated, an updated rejected takeoff energy parameter is determined based on the updated value of the aircraft weight. It should be noted that for lower values ​​of aircraft weight, the rejected takeoff energy parameter may indicate that the aircraft 100 will need to lose a lower amount of energy to perform a future rejected takeoff event. The method 400 may continue to block 410 as described above. If it is determined at block 410 that the estimated mass is sufficient to perform a future rejected takeoff event (for the updated value of the aircraft weight), the method proceeds to block 414 (optional block 412 may also be performed). At block 414, a first notification is issued. In this case, the first notification indicates that, although the estimated mass is insufficient to perform a future rejected takeoff event for the measured aircraft weight, the estimated mass will be sufficient to perform a future rejected takeoff event for the updated value of the aircraft weight. In response to the first notification, the pilot and / or other crew members associated with the aircraft 100 may elect to change the actual weight of the aircraft 100 (eg, by offloading luggage, etc.) in order to continue the flight in a safe manner.

[0072] Therefore, in the example of method 400 , by repeating this determination, the operating condition under which the brake 200 is able to perform a rejected takeoff event, ie, the aircraft weight in this example, may be found.

[0073] In the example of method 400, if it is determined at block 418 that the aircraft weight criteria are not met, then method 400 proceeds to Figure 4b (Note that the block "A" indicates the Figure 4a The box in Figure 4b It should be noted that when it has been determined that the estimated mass of the brake 200 is insufficient to perform a future rejected takeoff event for any of the determined aircraft weight values ​​used to perform the method 400, the method 400 proceeds to box 420.

[0074] At block 420, a second notification is issued. At block 422, repetition of the determination as to whether the brakes are capable of executing a future rejected takeoff event is stopped. This may occur in an example where the processor executing the method has a device in communication with the braking system of the aircraft 100.

[0075] The described storage media may be used with a processor of a computing device. For example, all or part of the methods described herein may be performed by one or more processors of a computing system 106 of an aircraft 100. In some examples, one or more processors of a computing device at a maintenance control center associated with the aircraft 100 may perform all or part of the described methods. In some examples, one or more processors of a computing device of an electronic flight bag used by a crew member of the aircraft 100 may perform all or part of the described methods. Figure 5 5 is a simplified schematic diagram of an apparatus 500, which is a computing device for performing all or part of the methods described herein. The apparatus 500 includes a processor 502 and a storage medium 504. The storage medium 504 may be a storage medium as described, and thus may store instructions that, when executed by the processor 502, cause the processor 502 to perform all or part of the methods described herein.

[0076] Other methods that may be performed based on instructions stored in storage medium 504 are described below.

[0077] The manner in which the wear state and the estimated wear state of the brake 200 may be determined is described below. In the case where the brake 200 is electrically actuated and controlled by an electronic brake controller, the measured wear value may be the length L of the brake disc 202 measured by the electronic brake controller. The electronic brake controller may, for example, control the position of the pressure plate 204 relative to the reaction plate 206 and thus be able to measure the length L.

[0078] In the case where the brake 200 is hydraulically actuated, a brake wear sensor 216 configured to measure a wear value may be provided. The brake wear sensor 216 may include a linear variable differential transformer (LVDT) sensor or a Hall effect sensor configured to measure a linear displacement of a component of the brake 200. For example, such a brake wear sensor 216 may measure the linear displacement of the pressure plate 204 when the brake 200 is fully applied, and the length L may be derived from the measured linear displacement.

[0079] In some examples, for example, the measured wear value may be a remaining length of a wear pin (not shown) associated with the brake 200. The wear pin may be a component that provides an indication of a change in the length L of the brake disc 202. For example, a decrease in the remaining length of the wear pin may correspond to a decrease in the length L of the brake disc 202. The remaining length of the wear pin may be a length of the wear pin extending from a component of the brake 200. For example, the remaining length of the wear pin may be a length of the wear pin extending from a surface of a piston housing of the brake 200 or another surface of a housing of the brake 200.

[0080] The wear pin may move with the brake disc 202 and relative to the surface used to measure its remaining length. The wear sensor 216 may be a sensor that is fixed relative to the surface used to measure the remaining length of the wear pin. Such a sensor may measure the position of the wear pin relative to the surface and thus may measure the change in the remaining length of the wear pin.

[0081] The estimated wear state can be an estimated wear state that the brake 200 will be in after a future use cycle of the brake 200 has occurred. The wear state of the brake 200 can be represented by a measured wear value, such as the remaining length of a wear pin measured by the brake wear sensor 216. As described, as the brake 200 becomes more worn, the length L of the brake disc 202 decreases. Therefore, the measured wear value as defined herein decreases as the use cycle occurs. The estimated wear state can be represented by an estimated wear value, which can be an estimated length associated with the brake 200, such as the estimated remaining length of the wear pin. In the examples described below, the actual wear state and the estimated wear state are represented by the measured wear value and the estimated wear value that decrease as the brake 200 becomes more worn.

[0082] The estimated wear state can be determined based on the wear state of the brake 200. For example, a wear relationship between the wear state of the brake 200 and the number of use cycles can be determined. The estimated wear state can be determined based on the wear relationship as described below. The wear relationship can be determined based on one or more of the measured wear values. For example, the wear state can be measured for the number of use cycles that have occurred, and the wear state is considered for the total number of use cycles of the brake 200 that have occurred. In the example described below, the wear state is measured for each use cycle that has occurred.

[0083] Figure 6 is a graph showing the wear state and the estimated wear state as a function of the number of use cycles of the brake 200 according to an example. Figure 6 The vertical axis of the graph of represents the wear value (measured or estimated), while the horizontal axis represents the number of use cycles. In this example, one hundred use cycles have occurred (i.e., the aircraft 100 has flown 100 times with the brakes 200 installed). Therefore, for each use cycle that has occurred, the value of the wear state measured by the brake wear sensor 216 is to the left of line 602. Line 602 is a vertical line that intersects the horizontal axis at one hundred use cycles. For convenience, the individual values ​​of the wear state are not shown. Instead, a solid line 604a fitted to the values ​​of the wear state is shown.

[0084] Any known data fitting method may be used to determine the solid line 604a. For example, a simple linear regression analysis may be used to determine the solid line 604a. Examples of other methods of fitting data include least squares, least absolute residual, binary fitting, etc. It should be understood that any suitable data fitting method may be used.

[0085] In this example, a linear function is used to fit the value of the wear state to produce a solid line 604a, which is a straight line. However, in some examples, a different function may be used. For example, a polynomial function, an exponential function, or another function that can describe the decrease in the wear state value according to the cycle that can be used may be used.

[0086] As described, in Figure 6 A linear function is used in the example. The linear function can be expressed according to the following formula 1:

[0087] y=mx+c (1)

[0088] In the above formula (1), y represents the value of the wear state, x represents the number of usage cycles, m represents the amount of brake wear per usage cycle (i.e., the gradient of the linear fit to the value of the wear state), and c represents the wear state when no usage cycle occurs (i.e., the value of the wear value measured when no usage cycle occurs, which can be, for example, the starting length of the wear pin).

[0089] By fitting the values ​​of the wear state, the unknown parameter values ​​in the fitting function used can be determined. In this example, the value of m can be determined by fitting the values ​​of the wear state using equation (1). The function used to fit the values ​​of the wear state and the parameters determined by the fitting represent the wear relationship.

[0090] To determine the estimated wear state after a given number of use cycles has occurred (i.e., the estimated wear value in this example), the given number of use cycles can be substituted into equation (1) as the value of parameter x. Then, using the values ​​of the parameters known from the fit on the right-hand side of equation (1), the estimated wear state after a given number of use cycles (i.e., the value of parameter y when x equals the given number of use cycles) can be calculated. Figure 6 , the dashed line 604b represents the value of the estimated wear state according to the number of use cycles. In other words, the line (i.e., the dashed line 604b obtained according to the fitting function and the determined parameters) can be determined for the value of the number of use cycles greater than the number of use cycles that actually occurred. In this example, the estimated wear state for the corresponding number of use cycles is the value that falls on the dashed line 604b.

[0091] Figure 7A method 700 of determining a thermal oxidation state of a brake of an aircraft landing gear assembly 102 (e.g., a brake assembly 200) is summarized in accordance with an embodiment of the present invention. The method 700 involves determining a thermal oxidation state of the brake assembly 200 after a braking event using a thermal oxidation model based on an initial thermal oxidation state prior to a braking event (which is also referred to as an initial thermal oxidation level) and a temperature profile of the brake with respect to time. The determined thermal oxidation state of the brake assembly 200 after the braking event may be referred to as an updated thermal oxidation state. This is because the thermal oxidation state of the brake assembly 200 after the braking event takes into account changes to the initial thermal oxidation state due to the braking event.

[0092] A braking event is an event associated with the application of brake assembly 200. For example, a braking event may include one or more applications of brake assembly 200 to slow or stop aircraft 100. In some examples, a braking event may be a portion of time during which brake assembly 200 is continuously applied. Whenever brake assembly 200 is applied, the temperature of brake assembly 200 may increase. This is because when brake assembly 200 is applied to reduce the speed of aircraft 100, some kinetic energy of aircraft 100 is absorbed into brake assembly 200 as heat, causing its temperature to increase. Therefore, it may be determined based on the change in temperature of brake assembly 200 whether brake assembly 200 has been applied.

[0093] At block 702 of method 700, a temperature profile and an initial thermal oxidation state of the brake assembly 200 are input. As described above, the temperature profile indicates changes in temperature over time. The input temperature profile may, for example, be associated with a life cycle of the aircraft 100. For example, the temperature profile may be for the entire life cycle of the aircraft 100, such as the time from when the aircraft 100 is at a check-in gate before a flight to when the aircraft 100 is at an arrival gate after a flight. Specifically, the temperature profile may indicate changes in temperature over time for all braking events that occur during a cycle. In other examples, the temperature profile may not be for the entire life cycle of the aircraft 100. For example, the temperature profile may be for a single braking event or a portion of a cycle with many braking events. In some examples, multiple temperature profiles belonging to a particular life cycle may be used to determine the thermal oxidation state of the brake assembly 200 after the life cycle.

[0094] The temperature profile may, for example, be associated with a usage cycle that has already occurred. In other words, the temperature profile may include actual data from temperature sensor 218 of aircraft 100 during a previous usage cycle. In such an example, the temperature profile is associated with real data. On the other hand, in some examples, the temperature profile may be an estimated temperature profile for an estimated future usage cycle of aircraft 100. In this context, the braking event may be an estimated future braking event.

[0095] (In the example where the temperature profile includes actual data) the temperature sensor 218 associated with the brake 200 (see Figure 2 ) to obtain a temperature curve. The temperature sensor 218 may be arranged in thermal contact with one of the brake discs. Figure 2 In an example of the invention, the temperature sensor 218 is disposed on the stator 210. In this example, the stator 210 is the brake disc that may reach the highest temperature. The temperature sensor 218 may be any type of temperature sensor suitable for use in an aircraft brake assembly. For example, the temperature sensor 218 may operate normally within the temperature range that the brake disc 202 may reach. For example, the temperature sensor 218 may be a thermocouple, a surface acoustic wave (SAW) sensor, an eddy current sensor, a resistive thermal sensor, a strain gauge, etc. If a temperature sensor is disposed on a portion of the brake 200 other than one of the brake discs 202, an indication of a relationship between the temperature measured by the temperature sensor and the temperature of the brake disc 202 may be used to determine the temperature of the brake disc 202. In some examples, the relationship indication may be determined by experiment. In some examples, the relationship indication may be determined using a brake thermal model.

[0096] The temperature sensor 218 can measure the temperature of the stator 210 at a given measurement interval during a time period in which the brake 200 is expected to be used. The length of the given measurement interval can be different. The given measurement interval can be regular, irregular, or regular for a period of time and irregular for a period of time. For example, the temperature sensor 218 can measure the temperature so that a curve of the temperature of the stator 210 relative to time is captured. In other words, the temperature sensor 218 measures the temperature of the stator 210 at a given measurement interval so that temperature information according to time is captured. For example, the processor of the computing system 106 can control the operation of the temperature sensor 218 based on instructions stored in a computer-readable storage medium of the computing system 106. The temperature measurement results captured by the temperature sensor 218 can be stored in the storage medium of the computing system 106, for example, together with the associated time data.

[0097] The initial thermal oxidation state of the brake assembly 200 is the thermal oxidation state of the brake assembly 200 prior to the braking event for which an updated thermal oxidation state is to be determined. For example, for a new brake assembly 200 installed in the aircraft 100, the initial oxidation state may indicate no oxidation. In some examples, the initial oxidation state of the newly installed brake assembly 200 may be set by aircraft maintenance personnel at the time of installation and may indicate no oxidation or some oxidation as assessed by the personnel performing the installation. In examples where the brake assembly 200 is not a new brake assembly, the initial oxidation state may be the oxidation state calculated the last time the instance of the method 700 was performed. In some examples, a brake or brake component that is not new may be installed on the aircraft 100. If temperature profile information for all previous braking events involving the brake or brake component is available, the thermal oxidation state at installation may be determined using the method 700 using the available temperature profile information or by other methods disclosed herein.

[0098] At box 704 of method 700, a thermal oxidation state (updated thermal oxidation state) after a braking event is determined using a thermal oxidation model. For example, a thermal oxidation model is applied based on an input temperature profile and an initial thermal oxidation state of the brake assembly 200. The thermal oxidation model indicates, for example, how the thermal oxidation state is expected to change over time for each temperature starting from the initial thermal oxidation state. The thermal oxidation model is an evolutionary model of thermal oxidation of the brake. Which thermal oxidation state is used may depend, for example, on the initial thermal oxidation state. Details and selection of an appropriate thermal oxidation model are further described below. In some examples, method 700 may be performed in real time during the life cycle of the aircraft 100. In the case where method 700 is performed in real time (i.e., in real time or near real time), for example, the temperature profile used may come from temperature data currently acquired by the temperature sensor 218. Therefore, at box 704, it is determined how the oxidation state changes from the initial oxidation state due to the temperature increase associated with the braking event in question.

[0099] After determining the updated thermal oxidation state, the initial thermal oxidation state can be set to the updated thermal oxidation state. In this way, the initial thermal oxidation state is kept synchronized with all previous braking events. In examples where the temperature profile involves more than one braking event, method 700 can be performed again to determine an updated thermal oxidation state after a subsequent braking event. Updating the initial thermal oxidation state in this manner can ensure that the initial thermal oxidation state for a subsequent braking event takes into account all previous braking events.

[0100] In the example of a temperature profile for an entire use cycle of the aircraft 100, the method 700 may be performed to determine a corresponding updated thermal oxidation state after each braking event during the use cycle. It should be appreciated that the process may be performed sequentially with respect to the chronological order of the braking events. This is so that the determination of an updated thermal oxidation state for each braking event is made from a starting point (initial thermal oxidation state) taking into account all previous braking events.

[0101] In method 700 , for example, an updated thermal oxidation state after a braking event may be determined using an appropriate thermal oxidation model based on the high temperature interval, the initial thermal oxidation state, and the thermal oxidation rate parameters.

[0102] Figure 8 8 is a flow chart of a method 800 illustrating actions that may be performed as part of the method 700. For example, the method 800 relates to a more specific example of block 704 of the method 700. Block 802 is the same as block 702 of the method 700, in which a temperature profile of the brake with respect to time and an initial thermal oxidation state of the brake assembly 200 are input. At block 804, the temperature profile is compared to a set of temperature criteria. The set of temperature criteria may include a set of temperature thresholds. For example, the set of temperature criteria may include a first temperature threshold of 400° C. and a second temperature threshold of 750° C. In other examples, different temperature thresholds may be used depending on the physical properties of the brake assembly 200. The comparison of the temperature profile may be performed sequentially, for example, in a chronological order of the temperature data contained in the temperature profile. For example, a temperature value may be compared to the set of temperature thresholds, and then, the next temperature value in time may be compared to the set of temperature thresholds.

[0103] In box 806, it is determined whether one or more temperature criteria are met. For example, if no temperature threshold is exceeded, the method 800 ends. It should be understood that thermal oxidation of the CC compound of the brake disc 202 is the most significant process at high temperatures. Therefore, the comparison of the temperature curve with a set of temperature thresholds identifies a high temperature event corresponding to a braking event that may cause thermal oxidation. As mentioned above, a braking event is, for example, the application of the brake assembly 200. However, a high temperature event is an event in which the temperature of the brake assembly exceeds at least one of the temperature thresholds due to the braking event. For example, if the temperature of the brake assembly 200 remains below all temperature thresholds during the braking event (i.e., the brake is applied), no high temperature event occurs during the braking event. On the other hand, if the temperature of the brake assembly exceeds the temperature threshold during the braking event, the portion of the braking event that exceeds the temperature threshold can be referred to as a high temperature event. If more than one temperature threshold is exceeded, the high temperature event can be the portion of the braking event that exceeds the highest temperature threshold.

[0104] The temperature thresholds may be set based on temperatures above which a significant amount of thermal oxidation is expected to occur. Thus, if any temperature thresholds are not exceeded, method 800 ends. This is because in this example, no braking event has occurred that caused sufficiently high temperatures for thermal oxidation. In such an example, the updated thermal oxidation state after the braking event may simply be set to the initial thermal oxidation state before the braking event in question.

[0105] On the other hand, if at least one of the temperature thresholds is exceeded, then at block 808 of method 800, a high temperature event is identified that corresponds to the braking event in question. The high temperature event corresponds to the portion of the temperature curve that is above the highest of the exceeded temperature thresholds. This is because the portion of the temperature curve that is above the highest of the exceeded thresholds corresponds to the portion of the braking event that exceeds the highest temperature threshold. Fig. 9 The identification of high temperature events is described. Fig. 9 is a graph showing a portion of an example temperature curve. Fig. 9 , the vertical axis represents the temperature of the brake assembly 200, while the horizontal axis represents time. In this example, the curve portion 902 indicates that the temperature of the brake assembly 200 exceeds the first temperature threshold 904 and the second temperature threshold 906. In this example, a high temperature event is identified as the portion of the curve 902 above the second temperature threshold 906 because the second temperature threshold 906 is the highest temperature threshold that is exceeded.

[0106] For a given time interval, the amount of thermal oxidation above the second temperature threshold 906 may be significantly greater than the amount of thermal oxidation above the first temperature threshold 904 but below the second temperature threshold 906. Therefore, in this example, the portion of the temperature curve below the second temperature threshold 906 is not considered. In other examples, such as when using the method 800 for real-time oxidation state monitoring as further described below, the portion of the temperature curve between the two temperature thresholds may be considered. It should be understood that Fig. 9 The graphs are merely example illustrations for illustration purposes.

[0107] At block 810, the time interval occupied by the high temperature event is determined as the high temperature interval. As mentioned above, the updated thermal oxidation state can be determined based on (among other factors) the high temperature interval. Fig. 9 In the example of FIG. 9 , the high temperature interval is determined as time interval 908 .

[0108] At box 812, a high temperature event value for the brake assembly 200 is determined for the high temperature interval. The high temperature event value is a temperature value attributed to a high temperature event. In some examples, the high temperature event value is an average temperature during the high temperature interval. An alternative to the high temperature event value being an average temperature is described below in the context of immediate oxidation monitoring.

[0109] At block 814, an oxidation rate parameter is calculated based on the high temperature event value and physical property information of the brake. For example, the oxidation rate parameter of the thermal oxidation reaction may be determined based on the Arrhenius equation as shown in equation 2 below:

[0110]

[0111] In equation 2, k(T) is the thermal oxidation rate, A is the pre-constant, and E A is the activation energy of the carbon atoms of the CC composite component of the brake assembly 200, R is the universal gas constant and T is the temperature. In this example, for a particular high temperature event, the temperature T in Equation 2 is set to the high temperature event value for the purpose of block 814. In this example, the thermal oxidation rate k(T) is the oxidation parameter determined at block 814. The activation energy E A The values ​​of the and pre-exponential constant A may depend on the physical properties of the CC composite components of the brake component 200 (in this example, the brake disc 202). For example, the values ​​of these parameters may depend on the density, porosity, manufacturing process, contaminants present in the CC composite structure, the surface finish of the component, and the surface coating of the brake component 200. The activation energy E A The value of the pre-exponential constant A may also vary depending on the high temperature event value and the initial thermal oxidation state. Therefore, to determine the oxidation parameters, the activation energy E may be selected based on the physical properties of the brake assembly 200, the high temperature event value, and the initial thermal oxidation state prior to the braking event in question. A and a suitable value of the pre-exponential constant A.

[0112] For example, the activation energy E A Can be inversely related to temperature. Activation energy E A The activation energy E may become lower at a temperature at which oxygen molecules are able to penetrate the surface of the brake disc 202 and oxidation of carbon deeper in the brake disc 202 may occur. For example, the activation energy E may be experimentally determined for different initial thermal oxidation amounts, temperatures, and physical properties of the brake under consideration prior to implementing the method 800. A and a suitable value for the pre-exponential factor A.

[0113] Fig.10 is a graph illustrating an example of the evolution of the thermal oxidation state of a brake disc of the brake assembly 200 over time for a specific temperature. Fig.10The vertical axis of the graph in represents a measurement result of thermal oxidation indicated by the thermal oxidation state Ox. For example, the thermal oxidation state Ox may be the mass proportion of the brake assembly 200 lost due to thermal oxidation of the brake disc 202. The evolution curve 1002 shows how the mass proportion lost due to thermal oxidation grows over time at a specific temperature. It should be noted that different evolution curves will indicate how the thermal oxidation rate Ox changes over time for different temperature values.

[0114] In this example, the thermal oxidation state Ox changes with time below the thermal oxidation state level 1004 in a different manner than it does above the thermal oxidation state level 1004. In this example, the thermal oxidation state Ox (i.e., mass lost due to thermal oxidation) is shown to increase nonlinearly with time below the oxidation state level 1004 and to increase approximately linearly with time above the oxidation state level 1004. In this example, the thermal oxidation state increases at an accelerating rate over time until the thermal oxidation state level 1004 is reached. After reaching the thermal oxidation state level 1004, the rate of change of the thermal oxidation state Ox over time remains generally constant. For example, the thermal oxidation state Ox may be increased by 100% over time. Fig.10 The portion of the graph of the thermal oxidation state below the thermal oxidation state level 1004 is regarded as the first thermal oxidation region, that is, region 1, and can be Fig.10 The portion of the graph of that is above the thermal oxidation state level 1004 is considered to be a second thermal oxidation region, ie, region 2.

[0115] In some examples, the activation energy E may be used based on which thermal oxidation zone the brake assembly 200 is in, as indicated by the initial thermal oxidation state. A and different values ​​of the pre-exponential constant A.

[0116] At box 816, a thermal oxidation model is selected based on the initial thermal oxidation state before the braking event. The thermal oxidation model describes the evolution of the thermal oxidation state Ox of the brake assembly 200 for different temperature values. In the case where the initial thermal oxidation state is in region 1, a thermal oxidation model that describes the evolution of the thermal oxidation state Ox in region 1 can be selected. In the case where the initial thermal oxidation state is in region 2, a thermal oxidation model that describes the evolution of the thermal oxidation state Ox in region 2 can be selected. For example, a first thermal oxidation model, i.e., model 1, can be selected for region 1, and a second thermal oxidation model, i.e., model 2, can be selected for region 2. Model 1 for region 1 that describes the nonlinear change of the thermal oxidation state Ox over time can be expressed by equation 3. Model 2 for region 2 that describes the linear change of the thermal oxidation state Ox over time can be expressed by the following equation 4.

[0117] Ox=1-[1-{k(T)×t eq (1-n)} 1 / 1-n ] (3)

[0118] Ox=k(T)×t eq (4)

[0119] In the above equations 3 and 4, k(T) is the thermal oxidation rate defined by equation 2. The parameter t eq is the equivalent time that it will take to reach the thermal oxidation state Ox at temperature T. The parameter n refers to the formula order and depends on the properties of the CC compound used in the brake assembly 200. The parameter n can be determined experimentally, for example, for a brake using a specific CC compound.

[0120] In some examples, a thermal oxidation model different from the thermal oxidation model described by equations 3 and 4 may be used. In some examples, a single thermal oxidation model that describes the evolution of the thermal oxidation state Ox for all thermal oxidation states Ox associated with the brake assembly 200 may be used. In some examples, more than two thermal oxidation models may be used for various ranges of thermal oxidation states Ox. The method 800 may be appropriately modified to use such an alternative thermal oxidation model. For example, a set of inputs different from the inputs described in this particular example of the method 800 may be applied to the thermal oxidation model depending on the situation.

[0121] It will be appreciated that block 816 may be performed at any stage of method 800 where block 802 was performed, as block 816 requires an initial thermal oxidation state.

[0122] At block 818, an updated thermal oxidation state for the high temperature event is determined using the selected thermal oxidation model based on the high temperature interval, the initial thermal oxidation state, and the determined thermal oxidation rate parameter. For example, the time taken to reach the initial thermal oxidation state from zero at the high temperature value is determined, and the high temperature interval is added to the time to determine t to be used in the selected thermal oxidation model. eq The value of t determined by this eq The value of and the thermal oxidation parameter are input into a formula selected from Equation 3 and Equation 4 above, resulting in an updated thermal oxidation state of the brake assembly 200 after the high temperature event as an output.

[0123] The updated thermal oxidation state may be set as the new initial thermal oxidation state for subsequent uses of the method 800 for subsequent high temperature events in the temperature profile.

[0124] In some examples, method 700 and / or method 800 may be performed in real time during a use cycle in which a braking event is occurring. In such examples, for example, portions of method 800 may be modified to allow for real-time brake oxidation monitoring, and the temperature profile may correspond to the temperature values ​​measured in real time. For example, the temperature information provided by temperature sensor 218 may be continuously compared with that set of temperature standards in accordance with box 804 of method 800, and high temperature events may be identified substantially as they occur. It will be understood that, although such oxidation state monitoring is described as being real-time, the extent to which it occurs in real time will depend on various hardware and software (e.g., processing speed) limitations. For example, there may be a time delay between the temperature values ​​corresponding to the high temperature events measured by temperature sensor 218 and those values ​​that ultimately result in an updated thermal oxidation state of brake assembly 200.

[0125] For example, a high temperature event may be identified as a portion of the temperature curve that is smaller than the portion in the examples described above. Fig. 9 , the portion of the curve portion 902 that appears within the time interval represented as 910 can be considered a high temperature event and the interval 910 is a high temperature interval of the high temperature event. In this example, for example, the high temperature event value can be taken as the temperature value measured at the beginning or end of the high temperature interval 910 or the average of these two temperature values. Unlike the above example, in the case of real-time monitoring, even if the temperature exceeds the second temperature threshold 906, the portion of the temperature curve between the first temperature threshold and the second temperature threshold can also be considered. In the case of real-time monitoring, any portion of the temperature curve above at least one temperature threshold (such as the portion represented by the interval 910) can be identified as a high temperature event. It will be understood that this modification can allow the thermal oxidation state of the brake assembly 200 to be updated when a high temperature event corresponding to a braking event occurs. In some examples, a high temperature event can be identified based on the time between subsequent temperature measurements made by the temperature sensor 218. For example, the interval 910 can be the time interval between subsequent temperature measurements made by the temperature sensor 218.

[0126] Methods 700 and 800 may be used to determine the thermal oxidation state of the brake assembly 200 in a real-time manner after or during an actual use cycle of the aircraft 100. In such examples, this determination may be made based on one or more temperature profiles that include braking events during the use cycle. As mentioned above, in some examples, the thermal oxidation state of the brake assembly 200 is determined using temperature profile information collected by the temperature sensor 218 with respect to a use cycle that has actually occurred.

[0127] On the other hand, in some examples, method 700 or method 800 may be used to estimate a future thermal oxidation state of brake assembly 200 after a first plurality of estimated future use cycles of aircraft 100. The first plurality of future use cycles may be a certain number of cycles after which a thermal oxidation threshold is reached. Each estimated future use cycle may include a corresponding plurality of braking events. For each estimated future use cycle, these estimates may be based on a corresponding estimated temperature profile of brake assembly 200 and a current thermal oxidation state. The current thermal oxidation state is, for example, an oxidation state taking into account all previous braking events experienced by brake assembly 200.

[0128] For example, the estimated temperature profile may be input into the method 700 or the method 800, such as in a time sequence, to determine a future thermal oxidation state of the brake assembly 200. The estimated temperature profile for an estimated future use cycle may be estimated based on a previous temperature profile for a previous actual use cycle of the aircraft 100. For example, a portion of a previous temperature profile associated with a landing phase may be used to estimate a landing phase portion of a temperature profile for a future use cycle. High temperature intervals, high temperature event values, etc. may be stored in a computer-readable storage medium when the method 700 or the method 800 is executed for an actual use cycle of the aircraft 100 for the purpose of estimating a future thermal oxidation state.

[0129] In some examples, data from a previous cycle may not be available, for example because the brake assembly 200 may be new. In some examples, sufficient data may not be available to reliably estimate a temperature profile for an estimated future use cycle. In such examples, a predetermined temperature profile may be used. The predetermined temperature profile may be a profile that is generally expected for a future use cycle of the aircraft 100.

[0130] The estimated temperature profile may, for example, take into account a future flight schedule for the aircraft 100. For example, for some of the estimated future use cycles of the aircraft, the aircraft 100 may be expected to land at an airport with a short runway, which may require high energy (i.e., high temperature) braking upon landing. For those estimated future use cycles, the estimated temperature profile may indicate high energy braking upon landing. It will be appreciated that various other factors may be considered in estimating the temperature profile, such as taxi time at various stages of the estimated future use cycle, waiting time between a taxi stage and a preceding landing stage, etc.

[0131] As mentioned above, the first plurality of estimated future use cycles may be a certain number of estimated future cycles after which the estimated future thermal oxidation state will reach a thermal oxidation threshold. For example, after a cycle in which the thermal oxidation threshold is reached, the estimation of the future thermal oxidation state may be stopped. In some examples, the estimation of the future thermal oxidation state is stopped as soon as the thermal oxidation threshold is reached. The thermal oxidation threshold may be an oxidation state at which the brake assembly 200 or a component of the brake assembly 200 needs to be repaired or replaced. For example, the brake assembly 200 may need repair if the mass of the brake assembly 200 is reduced by between 4% and 6.5% (e.g., by 5.7%), wherein the selected percentage threshold may be different, for example, depending on the density of the originally manufactured disc. In this example, the first plurality of estimated future use cycles is the number of cycles performed such that the proportion of mass lost due to thermal oxidation reaches or exceeds, for example, 5.7% (i.e., within the range of 4% to 6.5%).

[0132] On the other hand, in some examples, the estimation of the future thermal oxidation state may be stopped at the end of the following estimated future use cycle: during this future use cycle, the future thermal oxidation state is close to the thermal oxidation threshold so that it can be expected that the future thermal oxidation state will reach the thermal oxidation threshold during the next estimated future use cycle. In such an example, it can be considered that the thermal oxidation threshold is reached within the first plurality of estimated future use cycles. This is because: in fact, the aircraft 100 with the brake assembly 200 that is expected to reach the thermal oxidation threshold in a strict sense just in the next cycle will not be allowed to fly, and maintenance or replacement related to the brake assembly 200 can be performed at this time.

[0133] Using the first plurality of estimated future usage cycles, an indication can be given as to how many usage cycles can be performed before the brake assembly 200 or a component of the brake assembly 200 requires repair or replacement due to thermal oxidation. In examples where the thermal oxidation threshold is strictly reached or exceeded during the last future cycle in the first plurality of future cycles, the number of cycles before repair or replacement is required due to thermal oxidation can be estimated as one less than the number of cycles in the first plurality. In examples where the estimation of future thermal oxidation conditions is stopped when the thermal oxidation threshold is expected to be reached in the next cycle after the first plurality, the first plurality is taken as the number of cycles before repair and replacement is required due to thermal oxidation.

[0134] Fig.111 is a flow chart of a method 1100 for determining an amount of brake wear caused by a braking event using a brake wear model based on the amount of energy absorbed by the brake assembly 200 due to the braking event and a density parameter of the brake assembly 200. The amount of brake wear may be determined for all braking events that input energy to the brake assembly 200 during a process involving friction that will cause surface wear of the brake disc. For example, wear of the brake disc due to friction may cause the length of the brake disc 202 (e.g., Figure 2 The length L) shown decreases as brake disk material is lost due to friction.

[0135] For example, the amount of brake wear may be determined for braking events that do not involve any high temperature events. For method 1100, a braking event may be identified as an event in which the temperature of brake assembly 200 increases, for example, based on a temperature profile. In some examples, a braking event may be identified simply based on an indication that brake assembly 200 has been applied. For example, computing system 106 of aircraft 100 may detect when brake assembly 200 is applied and when brake assembly 200 is released.

[0136] At block 1102 of method 1100, energy input to brake assembly 200 during a braking event is determined. For example, energy input to brake assembly 200 during a braking event may be determined based on characteristics of aircraft 100 (e.g., mass of aircraft 100, speed of aircraft 100 during a braking event, etc.). Energy absorbed by brake assembly 200 may be calculated based on such characteristics of aircraft 100 by determining the kinetic energy of aircraft 100. For example, brake assembly 200 may absorb a given proportion of the kinetic energy of aircraft 100 to reduce the kinetic energy of aircraft 100. In some examples, energy input to brake assembly 200 may be determined based on measurements taken by instrumentation 108 of aircraft 100. For example, instrumentation 108 may include a tachometer associated with wheel 104 associated with brake assembly 200. In such an example, the tachometer measures the rotational speed of wheel 104, and changes in the rotational speed with respect to time may be used to determine energy absorbed by brake assembly 200.

[0137] In other examples, if the mass of the brake assembly 200 is known, the absorbed energy may be determined based on the increase in temperature of the brake assembly 200 while taking into account the specific heat of the brake assembly 200. In some examples, the mass of the brake assembly 200 may be determined based on the thermal oxidation state of the brake assembly 200 determined according to the above method, because, as described above, the thermal oxidation state may be represented as the amount of mass lost from the brake assembly 200 due to thermal oxidation.

[0138] At box 1104 of the method 1100, a density parameter of the brake assembly 200 is determined. The density parameter is, for example, a parameter indicating a decrease in the density of the brake assembly 200 compared to the original density, taking into account the mass that has been lost. The density of the brake assembly 200 may, for example, be reduced due to thermal oxidation. It will be appreciated that thermal oxidation results in a decrease in mass because carbon atoms react with oxygen to form carbon dioxide or carbon monoxide and are thus removed from the brake disc 202. However, thermal oxidation may not necessarily change the volume of the brake disc 202. This is because thermal oxidation may not act uniformly on a particular surface of the brake disc, but may occur up to a certain depth inside the brake disc.

[0139] The density parameter may be expressed as (1-Ox), where the thermal oxidation state Ox is expressed as a number between 0 and 1. For example, the density of the brake assembly 200 is reduced by a factor (1-Ox) compared to the initial density before any thermal oxidation occurs (i.e., when the brake assembly 200 is new). Therefore, the density parameter may be determined based on the initial oxidation state prior to the braking event.

[0140] In some examples, the reduced density of the brake assembly 200 may be determined based on measurements made by instruments included in the instrument 108. For example, the mass of the brake assembly 200 may be calculated based on the amount of energy absorbed by the brake assembly 200 (e.g., based on measurements from a tachometer) and the subsequent temperature increase of the brake assembly 200 (e.g., based on measurements from the temperature sensor 218). The reduced density of the brake assembly 200 may be determined based on the calculated mass of the brake assembly 200. The aircraft 100 may include the described wear pin associated with the brake assembly 200. Typically, the wear pin provides an indication of a reduction in the length L of the brake, and thus provides an indication of brake wear. For example, ground personnel may check the wear pin between cycles and obtain an updated volume value of the brake assembly 200. In some examples, there may be other ways to measure the change in the length L of the brake assembly 200. For example, a length sensor may be provided for the brake assembly 200, and / or an electrically actuated brake may be used. An updated volume value may be determined based on the reduced length L and used to determine the reduced density from the mass. During a single cycle, the change in volume of the brake assembly 200 may be negligible for purposes of calculating the density parameter, and an updated volume may be obtained after multiple cycles. From the reduced density, the density parameter may be determined.

[0141] At block 1106 of method 1100, a brake wear model is used to determine the amount of brake wear caused by the braking event based on the energy absorbed by the brake assembly 200 and the density parameter from block 1104. For example, the brake wear model of Equation 5 below is used to determine the mass lost by the brake assembly 200 due to wear during the wear event.

[0142]

[0143] In the above formula 5, m wear is the mass lost due to wear during a braking event, E brake is the energy absorbed by the brake assembly 200, and W, X, Y, and Z are constants. The constants W, X, Y, and Z may be predetermined, for example, by experimentation, and may vary depending on the properties of the brake assembly 200. The amount of brake wear for a braking event may be determined as a decrease in the length L of the brake assembly 200 based on the mass reduction due to brake wear during the braking event.

[0144] As mentioned above, in some examples, the initial thermal oxidation rate is used to determine the density parameter. In these examples, when a braking event occurs (during which a high temperature event also occurs), the initial thermal oxidation state may be used for the determination of block 1106. This is because brake wear occurs on a much shorter time scale than thermal oxidation.

[0145] The amount of brake wear determined for a braking event may be summed with the amount of brake wear in all previous braking events of the brake assembly 200 to determine a total amount of brake wear.

[0146] For example, method 1100 may be performed in real time during the time of a braking event, or for a use cycle that has already occurred using relevant data from the use cycle. Method 1100 may also be used to estimate the future brake wear of brake assembly 200 after a second plurality of estimated future use cycles of aircraft 100. The second plurality of estimated future use cycles may be a certain number of cycles after which the thermal oxidation threshold is reached. Each estimated future use cycle may include a corresponding plurality of braking events. For example, method 1100 may be performed for each braking event in the second plurality of estimated future use cycles. Wear amounts from each of these braking events may be added together to estimate future brake wear for the second plurality of estimated future use cycles. For each estimated future use cycle, these estimates may be based on an estimated amount of energy absorbed by the brake during the corresponding braking event and a corresponding estimated density parameter of the brake for the corresponding braking event. For example, braking events may be identified based on an estimated temperature profile and the energy absorbed by brake assembly 200 for these braking events may be determined. In other examples, the estimated amount of energy absorbed may be based on data from previous cycles. If the brake assembly 200 is new, or sufficient previous data is not available, an estimated amount of energy may be predetermined.

[0147] For the purpose of estimating future brake wear, method 1100 may be used in conjunction with method 700 or 800. In these examples, the most recent initial thermal oxidation state immediately prior to each estimated braking event (e.g., an estimated future braking event) is known. In this manner, the initial thermal oxidation prior to the future braking event in question may be used to determine the mass of brake assembly 200 and, therefore, the density parameter.

[0148] As described above, the second plurality of estimated future usage cycles can be a certain number of estimated future cycles after which the estimated future brake wear amount reaches the brake wear threshold. For example, the estimation of the future brake wear amount can be stopped after the cycle that reaches the brake wear threshold. In some examples, the estimation of the future brake wear amount can be stopped once the total amount of brake wear reaches the brake wear threshold. The brake wear threshold can be the total amount of brake wear when the brake assembly 200 or a component of the brake assembly 200 needs to be repaired or replaced. For example, after the brake assembly (e.g. Figure 2If the length L of the brake assembly 200 is reduced by, for example, 22% to 24% depending on the type of disc and its initial manufacturing density, the brake assembly may need repair. For an exemplary disc having an initial length L of about 221 mm, a length reduction of about 60 mm to 64 mm may cause repair or replacement. In this example, the second plurality of estimated future use cycles is the number of cycles required for the total amount of brake wear to reach or exceed, for example, 60 mm to 64 mm (again, this is for an initial disc having a length L of about 221 mm).

[0149] On the other hand, in some examples, the estimation of the future brake wear amount may be stopped at the end of the estimated future use period, during which the total amount of brake wear approaches the brake wear threshold, so that it can be expected that the total amount of brake wear will reach the brake wear threshold during the next estimated future use period. In such an example, it can be considered that the brake wear threshold is reached within the second plurality of estimated future use periods. This is because, in practice, an aircraft 100 having a brake assembly 200 that is expected to reach the brake wear threshold in a strict sense in the next period will not be allowed to fly and maintenance or replacement related to the brake assembly 200 can be performed at this time.

[0150] By using the second plurality of estimated future use cycles, an indication can be given as to how many use cycles may be performed before the brake assembly 200 or a component of the brake assembly 200 requires repair or replacement due to brake wear. In examples where the brake wear threshold is strictly reached or exceeded during the last cycle in the second plurality of future cycles, the number of cycles before repair or replacement is required due to brake wear can be estimated to be one less than the number of cycles in the second plurality of estimated future use cycles. In examples where the estimation of the amount of future brake wear is stopped when it is expected that the brake wear threshold will be reached in the next cycle after the second plurality of estimated future use cycles, the second plurality of estimated future use cycles is taken to be the number of cycles before repair or replacement is required due to brake wear.

[0151] Fig.121 is a flow chart of a method 1200 for determining the number of good future use cycles until one of a thermal oxidation threshold and a brake wear threshold is reached. The number of good future use cycles is the number of future use cycles remaining before reaching one of the thermal oxidation threshold or the brake wear threshold. The method 1200 can be performed for multiple estimated future use cycles until the first of the thresholds is reached. The method 1200 involves estimating the future thermal oxidation state and the future brake wear amount after the estimated future use cycle, and in the case of reaching one of the thermal oxidation threshold and the brake wear threshold, determining the number of good future use cycles before reaching either of the thresholds. In the case of not reaching one of the thresholds, the estimation is performed for the next estimated future use cycle. As in the above example, each estimated future use cycle includes multiple braking events. For each estimated future use cycle, these estimates are based on a corresponding brake estimated temperature profile, a current thermal oxidation state, an estimated amount of energy absorbed by the brake during the corresponding braking event, and a corresponding brake estimated density parameter for the corresponding braking event.

[0152] The number of good future use cycles is the number of cycles after which the brake assembly 200 or a component of the brake assembly 200 may need to be repaired or replaced. It should be understood that when one of the thermal oxidation threshold or the brake wear threshold is first reached, the repair or replacement related to the brake assembly 200 can be performed. Which threshold is reached first can depend, for example, on the manner in which the aircraft 100 is operated during use and its flight schedule. For example, if the schedule of the aircraft 100 involves flying to airports that mostly have long runways, short taxiways, etc., the brake wear threshold may be reached first. This is because, in such examples, the temperature of the brake assembly 200 may not often exceed any temperature threshold related to thermal oxidation. On the other hand, the aircraft 100 may often experience high-energy braking (e.g., due to a short runway) resulting in temperatures above the thresholds related to thermal oxidation. In such examples, the thermal oxidation threshold may be reached first.

[0153] However, as described above, in some examples, it may be determined whether the brakes 200 are capable of executing a future rejected takeoff event. If it is determined that the brakes are capable of executing a future rejected takeoff event regardless of whether the threshold is reached, the brakes 200 may be deemed safe to use. However, in some examples, if the estimated future oxidation state is too severe to make use of the brakes 200 undesirable, the brakes 200 may be deemed unsafe to use.

[0154] At block 1202 of method 1200, a future thermal oxidation state after an estimated future use cycle is estimated. The estimation of the future thermal oxidation state is performed as described above, for example, using an appropriate thermal oxidation model based on the estimated temperature profile of the estimated future use cycle in question. At block 1204 of method 1200, a future brake wear amount after the same estimated future use cycle is estimated. This estimation is performed in the context of method 1100 as described above.

[0155] At block 1206 of method 1200, a determination is made as to whether a thermal oxidation threshold and / or a brake wear threshold is reached. For example, if the thermal oxidation threshold is reached, method 1200 proceeds to block 1208 where a number of good future use cycles before either the thermal oxidation threshold or the brake wear threshold is reached is determined, and method 1200 ends. For example, if the thermal oxidation threshold is strictly reached or exceeded after a given number of estimated future use cycles, the number of good future use cycles is one less than the given number. For example, if the thermal oxidation threshold is expected to be reached in the next estimated future use cycle, the number of good future use cycles is determined to be the number of estimated future use cycles for which method 1200 has been executed so far.

[0156] On the other hand, if it is determined that the brake wear threshold is reached, the method proceeds to block 1208 where the number of good future use cycles is determined and the method 1200 ends. For example, if the brake wear threshold is strictly reached or exceeded after a given number of estimated future use cycles, the number of good future use cycles is one less than the given number. For example, if the brake wear threshold is expected to be reached in the next estimated future use cycle, the number of good future use cycles is determined to be the number of estimated future use cycles for which the method 1200 has been executed so far.

[0157] For example, if both thresholds are reached, the method 1200 proceeds to block 1208 where the number of good future use cycles remaining before reaching the thermal oxidation threshold or the brake wear threshold is determined, and the method 1200 ends. In this example, if at least one of the thresholds is strictly reached or exceeded after a given number of estimated future use cycles, the number of good future use cycles is one less than the given number. Otherwise, the number of good future use cycles is determined to be the number of estimated future use cycles for which the method 1200 has been executed so far.

[0158] If the brake wear threshold has not been reached, method 1200 proceeds to block 1210 and blocks 1202 through 1210 are repeated for the next estimated future usage period.

[0159] In this manner, the number of good future use cycles can be estimated based on which of the thermal oxidation threshold and the brake wear threshold is reached first. This is because once the first of these thresholds is reached, the brake assembly 200 may need to be repaired or replaced, or a component of the brake assembly 200 may need to be repaired or replaced. It should be understood that, for example, if the thermal oxidation threshold is reached but the brake wear threshold is not reached, the brake assembly 200 will not continue to be used. It should also be understood that the blocks of method 1200 can be executed in any suitable order. For example, block 1204 can be executed before block 1202, and / or block 1210 can be executed before block 1206.

[0160] One or more of the methods described above, i.e., methods 700, 800, 1100, 1200, or any variation thereof (e.g., instantaneous determination of oxidation or brake wear, or estimation of future thermal oxidation state or future brake wear, etc.) may be performed by a processor of a computing system 106 of an aircraft 100, for example, based on instructions stored in a computer-readable storage medium of the computing system 106. For example, a processor of the computing system 106 may perform monitoring of thermal oxidation state (following a use cycle or in real time). Alternatively or in addition, a processor of the computing system may perform monitoring of brake wear (following a use cycle or in real time). Alternatively or in addition to any of these examples, an estimation related to future thermal oxidation state and / or future brake wear state may be performed by a processor of the computing system 106. These methods may be performed, for example, using data from an instrument 108. For example, temperature data measured by a temperature sensor 218 may be used. In the case of an estimation, a future temperature profile and / or other estimation data may be estimated by a processor of the computing system 106. Alternatively, data used for the estimation may be determined on a computing system not onboard aircraft 100 and may be stored in a computer-readable storage medium of computing system 106 .

[0161] All or part of the instructions for performing the above methods can be generated, and / or any suitable software or combination of software can be used to perform these methods. In one example, "MATLAB" can be used to generate all or part of the instructions for a processor (such as a processor 502 or a processor of a computing system 104) to perform any of the above methods. In other examples, other software packages can be used. For example, any suitable programming language, development environment, software package, etc. can be used. Other examples of programming languages ​​include PYTHON, C++, C, JAVASCRIPT, FORTRAN, etc.

[0162] It should be noted that the term “or” used herein should be interpreted as meaning “and / or” unless explicitly stated otherwise. It should be understood that the temperature characteristics determined according to the above method may be expected temperature characteristics expected according to the model applied to determine the relationship information.

Claims

1. A non-transitory computer-readable storage medium having stored thereon instructions that, when executed by a processor, cause the processor to: Determine if the aircraft wheel brakes are capable of performing future rejected takeoff events, including: determining whether the estimated mass of the brake is sufficient to execute the future rejected takeoff event based on the rejected takeoff energy parameter and the brake parameter set, Wherein, when the instruction is executed by the processor, the processor further performs the following operations: determining a mass limit, the mass limit defining a minimum mass required to perform the future rejected takeoff event; and A determination is made as to whether the estimated mass is sufficient to perform the future rejected takeoff event by comparing the estimated mass to the mass limit.

2. The non-transitory computer-readable storage medium of claim 1, wherein: When executed by a processor, the instructions cause the processor to perform the following operations: A number of estimated future usage cycles is determined, wherein it is expected that after the number of estimated future usage cycles the estimated quality will be insufficient to perform the future rejected takeoff event.

3. The non-transitory computer-readable storage medium according to claim 1 or 2, wherein: When executed by a processor, the instructions cause the processor to perform the following operations: The mass limit is determined using an amount of energy that will be absorbed by the brake when executing the future rejected takeoff event, determined based on characteristics of the brake.

4. The non-transitory computer-readable storage medium according to claim 1 or 2, wherein: When executed by a processor, the instructions cause the processor to perform the following operations: An estimated number of future usage cycles for the estimated quality to decrease to the quality limit is determined.

5. The non-transitory computer-readable storage medium according to claim 1 or 2, wherein: When executed by a processor, the instructions cause the processor to perform the following operations: If it is determined that the estimated quality is sufficient to perform the future rejected takeoff event, a first notification is issued.

6. The non-transitory computer-readable storage medium according to claim 1 or 2, wherein: When executed by a processor, the instructions cause the processor to perform the following operations: If it is determined that the estimated mass is insufficient to perform the future rejected takeoff event, a determination as to whether the brakes are capable of performing the future rejected takeoff event is repeated.

7. The non-transitory computer-readable storage medium of claim 6, wherein: The determination is repeated using an updated rejected takeoff energy parameter determined based on the updated aircraft weight.

8. The non-transitory computer-readable storage medium of claim 7, wherein: When executed by a processor, the instructions cause the processor to perform the following operations: In response to the updated aircraft weight satisfying the aircraft weight criteria, a second notification is issued indicating that the brake requires maintenance or replacement, and repeating the determination is stopped.

9. The non-transitory computer-readable storage medium according to claim 1 or 2, wherein: When executed by a processor, the instructions cause the processor to perform the following operations: The rejected takeoff energy parameter is determined based on a set of user input parameters.

10. The non-transitory computer-readable storage medium according to claim 1 or 2, wherein: The brake parameter set includes an upper temperature cutoff for the brake.

11. A method for determining brake characteristics, comprising: Determine if the aircraft wheel brakes are capable of performing future rejected takeoff events, including: determining whether the estimated mass of the brake is sufficient to execute the future rejected takeoff event based on the rejected takeoff energy parameter and the brake parameter set, Wherein, the method further comprises: determining a mass limit, the mass limit defining a minimum mass required to perform the future rejected takeoff event; and A determination is made as to whether the estimated mass is sufficient to perform the future rejected takeoff event by comparing the estimated mass to the mass limit.

12. The method according to claim 11, comprising: A number of estimated future usage cycles is determined, wherein it is expected that after the number of estimated future usage cycles the estimated quality will be insufficient to perform the future rejected takeoff event.

13. An apparatus for determining a brake characteristic, comprising a processor configured to: Determine if the aircraft wheel brakes are capable of performing future rejected takeoff events, including: determining whether the estimated mass of the brake is sufficient to execute the future rejected takeoff event based on the rejected takeoff energy parameter and the brake parameter set, Wherein, the processor is further configured to: determining a mass limit, the mass limit defining a minimum mass required to perform the future rejected takeoff event; and A determination is made as to whether the estimated mass is sufficient to perform the future rejected takeoff event by comparing the estimated mass to the mass limit.

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