System and method for mitigating structural loads on pivoting main landing gear

Abstract

The present invention relates to systems and methods for mitigating structural loads on pivoting main landing gear. A pivoting turn load mitigation (PTLA) braking system is provided for mitigating structural loads on a pivoting main landing gear of an aircraft during a pivoting turn maneuver. The PTLA braking system includes a braking control system operably coupled to at least two main landing gears, each main landing gear having two or more wheels. The PTLA braking system also includes a PTLA brake inhibition subsystem coupled to the braking control system. During the pivoting turn maneuver, the subsystem inhibits braking of one or more of the two or more wheels of the pivoting main landing gear such that at least one of the two or more wheels is in an unbraked state and the remaining number of two or more wheels is in a braked state. The PTLA braking system mitigates structural loads and reduces wear on at least one wheel in the unbraked state.

Description

Technical Field

[0001] The present disclosure relates generally to systems and methods for braking an aircraft, and more particularly to systems and methods for braking a pivoting main landing gear of an aircraft during and in a pivot-turn maneuver. Background Art

[0002] Large transport aircraft, whether commercial or military, typically include a main landing gear arrangement that supports most of the aircraft's weight, along with a nose landing gear for stability and steering. The main landing gear typically includes a left main landing gear and a right main landing gear, each main landing gear having a plurality of wheels, and each wheel including one or more brakes.

[0003] The wheel brakes on the main landing gear are controlled by the pilot after landing to assist in ground deceleration of the aircraft. The pilot can also control the wheel brakes during ground taxi maneuvers, and during pivot turn maneuvers or 2-point turn maneuvers performed on the ground. The large mass and high landing speed of the aircraft result in very high momentum, which can translate into very high structural loads during braking maneuvers, such as when the brakes are suddenly applied.

[0004] There are known systems and methods for braking the main landing gear during a pivot turn maneuver. However, such known systems and methods brake all wheels on the pivoting main landing gear. Braking all wheels on the pivoting main landing gear during a pivot turn maneuver may result in excessive wear on the wheels and tires, as well as increased structural and braking loads on the pivoting main landing gear. Furthermore, known systems and methods may require the use of heavy and bulky main landing gear assemblies and components to withstand the high structural and braking loads experienced during a pivot turn maneuver.

[0005] Therefore, there is a need in the art for systems and methods that avoid braking all wheels on a pivoting main landing gear and allow certain wheels on the pivoting main landing gear to roll freely during a pivoting turning maneuver, reduce structural loads on the pivoting main landing gear during a pivoting turning maneuver, reduce the weight of main landing gear assemblies and components designed to withstand high loads during a pivoting turning maneuver, and provide significant advantages over known systems and methods. Summary of the invention

[0006] Exemplary implementations of the present disclosure provide systems and methods for braking a pivoting main landing gear of an aircraft in and during a pivoting turn maneuver.As discussed in the detailed description below, versions of the systems and methods may provide significant advantages over existing systems and methods.

[0007] In one exemplary version, a pivot turn load mitigation (PTLA) braking system is provided for mitigating structural loads on pivoting main landing gear of an aircraft during a pivot turn maneuver. The PTLA braking system includes a braking control system operably coupled to at least two main landing gears. Each of the at least two main landing gears has two or more wheels. The braking control system controls braking of the at least two main landing gears.

[0008] The PTLA braking system also includes a pivot turn load mitigation (PTLA) brake inhibition subsystem coupled to the brake control system. During a pivot turn maneuver, the PTLA brake inhibition subsystem inhibits braking of one or more wheels of two or more wheels of one main landing gear comprising the pivoting main landing gear, such that at least one of the two or more wheels is in an unbraked state and the remaining number of the two or more wheels is in a braked state. The PTLA braking system mitigates structural loads on the pivoting main landing gear of the aircraft during the pivot turn maneuver and reduces wear on the at least one wheel in the unbraked state.

[0009] In another version, an aircraft is provided. The aircraft includes a fuselage, one or more wings attached to the fuselage, and a plurality of landing gears attached to the fuselage. The plurality of landing gears includes a nose landing gear and at least two main landing gears. Each of the at least two main landing gears has two or more wheels. During a pivoting turning maneuver of the aircraft, one of the at least two main landing gears includes a pivoting main landing gear.

[0010] The aircraft also includes a pivot turn load alleviation (PTLA) braking system. The PTLA braking system includes a braking control system operably coupled to at least two main landing gears. The braking control system controls braking of the at least two main landing gears.

[0011] The PTLA braking system also includes a pivot turn load mitigation (PTLA) brake inhibition subsystem coupled to the brake control system. During a pivot turn maneuver, the PTLA brake inhibition subsystem inhibits braking of one or more wheels of two or more wheels of one main landing gear comprising the pivoting main landing gear such that at least one of the two or more wheels is in an unbraked state and the remaining number of the two or more wheels is in a braked state. The PTLA braking system mitigates structural loads on the pivoting main landing gear during a pivot turn maneuver of the aircraft and reduces wear on the at least one wheel in the unbraked state.

[0012] In another version, a method for mitigating structural loads on a pivoting main landing gear of an aircraft during a pivot turn maneuver is provided. The method includes the step of initiating a pivot turn maneuver with the aircraft. The aircraft has a pivot turn load mitigation (PTLA) braking system. The PTLA braking system includes a braking control system operably coupled to at least two main landing gears. Each of the at least two main landing gears has two or more wheels. The braking control system controls braking of the at least two main landing gears. The PTLA braking system also includes a pivot turn load mitigation (PTLA) braking inhibition subsystem coupled to the braking control system.

[0013] The method further includes the step of initiating a pivot turn load mitigation (PTLA) brake inhibit command of the PTLA brake inhibit subsystem to one or more brake control units of the brake control system once one or more brake inhibit conditions are satisfied. The method further includes the step of inhibiting braking of one or more of the two or more wheels of the pivoting main landing gear during a pivot turn maneuver such that at least one of the two or more wheels is in an unbraked state and the remaining number of the two or more wheels is in a braked state. The PTLA brake system mitigates structural loads on the pivoting main landing gear of the aircraft during the pivot turn maneuver and reduces wear on the at least one wheel in the unbraked state.

[0014] The features, functions, and advantages that have been discussed can be achieved independently in various versions of the present disclosure or may be combined in yet other embodiments, further details of which can be seen with reference to the following description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present disclosure may be better understood by reference to the following detailed description taken in conjunction with the accompanying drawings, which show preferred and exemplary versions, but are not necessarily drawn to scale, and in which:

[0016] Figure 1A is an illustration of a perspective view of an aircraft having a pivot turning load alleviation (PTLA) braking system according to a version of the present disclosure;

[0017] Figure 1B yes Figure 1A An illustration of a top plan view of an aircraft and a PTLA braking system;

[0018] Figure 2A is a diagram showing a functional block diagram of an aircraft having an exemplary PTLA braking system of the present disclosure;

[0019] Figure 2B The diagram shows a PTLA entry scenario and a PTLA exit scenario. Figure 2AIllustration of a functional block diagram of an aircraft and PTLA brake inhibition subsystem;

[0020] Figure 3A is an illustration of a schematic diagram of one version of a PTLA brake system command logic diagram;

[0021] Figure 3B is an illustration of a schematic diagram of another version of a PTLA brake system command logic diagram;

[0022] Figure 3C is an illustration of a schematic diagram of yet another version of a PTLA brake system command logic diagram;

[0023] Figure 4 is an illustration of a graph showing a first pivot turn brake pedal curve;

[0024] Figure 5 is an illustration of a graph showing a second pivot turn brake pedal curve;

[0025] Figure 6 is an illustration of a graph showing a third pivot turn brake pedal curve;

[0026] Figure 7 is an illustration of a graph showing a fourth pivot turn brake pedal curve;

[0027] Figure 8 is an illustration of a flow chart showing an exemplary version of the method of the present disclosure;

[0028] Fig. 9 A flowchart that is a version of an aircraft manufacturing and maintenance methodology; and

[0029] Fig.10 is an illustration of a functional block diagram of a version of an aircraft.

[0030] The figures shown in this disclosure are representative of various aspects of the versions presented, and only the differences will be discussed in detail. DETAILED DESCRIPTION

[0031] The disclosed versions or embodiments will now be described more fully below with reference to the accompanying drawings, in which some, but not all, of the disclosed versions are shown. In fact, several different versions may be provided, and should not be construed as being limited to the versions set forth herein. Rather, these versions are provided so that the disclosure is thorough and fully conveys the scope of the disclosure to those skilled in the art.

[0032] Now referring to the accompanying drawings, Figure 1A is an illustration of a perspective view of an aircraft 10 having a pivot turning load alleviating (PTLA) braking system 12 configured in accordance with a version of the present disclosure, Figure 1B yes Figure 1AFIG. 1 is an illustration of a top plan view of an aircraft 10 and a PTLA braking system 12 . Figure 2A is an illustration showing a functional block diagram of an aircraft 10 having an exemplary PTLA braking system 12 of the present disclosure.

[0033] Figure 2A The boxes in the figure represent elements, and the lines connecting the boxes do not imply any specific dependency of the elements. In addition, the connecting lines shown in the various figures contained herein are intended to represent example functional relationships and / or physical connections between the various elements, but it is noted that other alternative or additional functional relationships or physical connections may exist in the versions disclosed herein.

[0034] like Figure 1A to Figure 1B and Figure 2A As shown, the PTLA brake system 12 includes a brake control system 14 and a pivoting turn load alleviation (PTLA) brake inhibition subsystem 16 coupled to the brake control system 14. Figure 1A to Figure 1B As shown, the aircraft 10 includes a fuselage 18, one or more wings 20 coupled to the fuselage 18, and a tail section 21. The aircraft 10 may be launched via landing gear 22 (see FIG. Figure 1A , Figure 1B , Figure 2A ) is supported at multiple points, including the main landing gear (MLG) 24 (see Figure 1A to Figure 1B , Figure 2A ) and front landing gear 26 (see Figure 1A to Figure 1B ).like Figure 1A to Figure 1B As shown, the main landing gear 24 is positioned rearward of the front landing gear 26, and the main landing gear 24 includes a left main landing gear 24a and a right main landing gear 24b.

[0035] In one version disclosed herein, a PTLA braking system 12 is provided for mitigating the impact of a pivoting turn 30 (see FIG. Figure 2A ) or during a pivoting turn maneuver 30 performed or executed by the aircraft 10, including the pivoting main landing gear 32 of the aircraft 10 (see Figure 2A ) on at least one main landing gear 24, such as a structural load 28a (see Figure 2A ) load 28 (see Figure 2A During the pivoting turn maneuver 30, for example, if the aircraft 10 has two main landing gears 24, one main landing gear 24 includes a pivoting main landing gear 32 (see Figure 2A ), while the other main landing gear 24 (see Figure 2A ) includes a non-pivoting main landing gear 34. The pivoting main landing gear 32 is closer to the turning center 33 of the pivoting turning maneuver 30 or pivoting turn than the non-pivoting main landing gear 34 (see Figure 2A). The pivoting main landing gear 32 is closest to or proximate to the turning center 33 of the pivoting turn maneuver 30 or pivoting turn. The torque is high when pivoting near the center of the pivoting main landing gear 32. During the pivoting turn maneuver 30, one main landing gear 24 is braking and pivoting about the braking main landing gear 24, while the other main landing gear 24 moves circumferentially about the braking main landing gear 24. There are usually two brake pedals 64 (see Figure 2A ), such as the left brake pedal 64a (see Figure 2A ) and right brake pedal 64b (see Figure 2A ), each brake pedal 64 commands a different main landing gear 24, and each brake pedal 64 can be operated by a different pilot 154 (see Figure 2B ).

[0036] like Figure 1A As shown, the main landing gear 24 is a 2-main landing gear configuration 36 (see also Figure 2A ).although Figure 1A The main landing gear 24 is shown as a 2-main landing gear configuration 36. The PTLA braking system 12 can also be used in a 3-main landing gear configuration 38 (see FIG. Figure 2A ), 4-main landing gear structure 40 (see Figure 2A ) or other suitable main landing gear configuration.

[0037] like Figure 1A to Figure 1B As shown, each main landing gear 24 may include a strut 42 that carries a wheel carrier 44. The wheel carrier 44 may include a plurality of wheels 46 (see FIG. Figure 1A to Figure 1B , Figure 2A ), the plurality of wheels 46 are selectively or collectively braked to reduce the speed of the aircraft 10 during taxiing maneuvers and post-landing rollout. The aircraft 10 has at least two main landing gears 24, and each of the at least two main landing gears 24 has two or more wheels 46. For example, each main landing gear 24 may have two wheels, four wheels, six wheels, or other suitable number of wheels. In the case where the at least two main landing gears 24 include a left main landing gear 24a and a right main landing gear 24b, each of the left main landing gear 24a and the right main landing gear 24b may have two pairs 48 (see Figure 2A ) wheel 46. Each pair of 48 wheels 46 is arranged on axle 49 (see Figure 2A ), such as a common axis or a single axis. As discussed in more detail below, during the pivot turn maneuver 30, one or more wheels 46, such as one or more of the two or more wheels 46, may be in an unbraked state 52 (see Figure 2A ) of one or more unbraked wheels 46a (see Figure 2A ) and the remaining number 54 (see Figure 2A ) of the wheels 46, for example two or more wheels 46, may be in a braking state 56 (see Figure 2A) of the brake wheel 46b (see Figure 2A ). In one version, FIG. 3A to FIG. 3C As shown, each of the main landing gears 24, including the left main landing gear 24a and the right main landing gear 24b, may include two front wheels 46c and two rear wheels 46d, and may also include two inner wheels 46e and two outer wheels 46f.

[0038] Each wheel 46 has one or more brakes 58 (see Figure 1A to Figure 1B , Figure 2A ), the one or more brakes 58 are coupled to or located at the wheel 46. Figure 1A to Figure 1B As shown, the brake control system 14 is operably coupled to at least two main landing gears 24 and operably coupled to brakes 58. The brake control system 14 is configured to control braking of the at least two main landing gears 24. The brake control system 14 can direct the application of various combinations of brakes 58 based on one or more aircraft characteristics or parameters, as will be discussed in more detail below. The brake control system 14 can also inhibit braking of selected brakes 58 based on these characteristics or parameters.

[0039] Thus, the brake control system 14 may receive pilot input 60 (see Figure 1A to Figure 1B , Figure 2A ) (e.g., via the flight deck 66 of the aircraft 10 (see Figure 2A ) at the brake pedal 64 (see Figure 2A ) received command signal 62 (see Figure 2A )), threshold 68 (see Figure 1A to Figure 1B , Figure 2A ) and aircraft data 70 (see Figure 1A to Figure 1B , Figure 2A ). In particular, using the version of the PTLA braking system 12 of the present disclosure, the aircraft data 70 and the thresholds 68 may be used to determine which brakes 58 to apply and which brakes 58 to inhibit, as will also be described in greater detail below.

[0040] like Figure 2A As shown, the brake control system 14 includes a brake controller 72 having a plurality of brake control units 74. The brake control unit 74 includes an electronic control unit that controls a command signal 62 representing a brake command 76. The brake control unit 74 can be implemented with the brake controller 72, for example in the form of a processor, a microprocessor or other suitable controller device. The brake control unit 74 can be used with suitable hardware components, suitable software or programmable logic, memory elements, etc., and the brake control unit 74 can perform various functions under the control of the brake controller 72 or other suitable control device. In one version, one or more of the brake control units 74 can be implemented with a computer processor that houses the software and provides an external interface for the software.

[0041] The brake control system 14 may also include a plurality of controls 78 (see Figure 2A ), such as one or more of wheel speed control, fluid temperature control, wheel temperature control, valve control, brake control, parking brake control, wheel power control, anti-skid control, taxi brake release control, or other suitable control. Brake control system 14 may be powered by power source 80 (see Figure 2A ) is powered, for example, by an electrical power source or other suitable power source.

[0042] like Figure 2A As further shown, the brake control system 14 includes a plurality of brake control valves 82. Each brake control valve 82 has a first end 84a (see FIG. 3A to FIG. 3C ) and the second end 84b (see FIG. 3A to FIG. 3C The first end 84a of the brake control valve 82 is connected to an electronic connector element 86 such as an electric wire (see FIG. 3A to FIG. 3C ) or other suitable connector element is coupled to one or more brake control units 74. The second end 84b of each brake control valve 82 is coupled to one or more brakes 58 on each wheel 46 via a hydraulic connector element 88, such as a hydraulic line or other suitable connector element. One or more of the plurality of brake control units 74 generates one or more brake commands 76 (see Figure 2A Those skilled in the art will appreciate that versions of the PTLA braking system 12 may be implemented using different aircraft braking control systems and aircraft configurations, and that the braking control system 14 described herein is merely one exemplary version.

[0043] like Figure 1A to Figure 1B and Figure 2A As further shown, the PTLA braking system 12 includes a PTLA braking inhibition subsystem 16 coupled to the PTLA braking system 12. The PTLA braking inhibition subsystem 16 is configured to inhibit braking during and during the pivoting turning maneuver 30 of the aircraft 10, and is configured to inhibit brakes 58 of one or more of the two or more wheels 46 of one of the main landing gear 24 including the pivoting main landing gear 32, such that at least one of the two or more wheels 46 is in an unbraked state 52 (see FIG. Figure 2A ), for example, scroll state 53 (see Figure 2A ) or inhibition state 57 (see Figure 2A ), and the remaining number 54 of the two or more wheels 46 (see Figure 2A ) is in braking state 56 (see Figure 2A ).

[0044] The PTLA brake inhibit subsystem 16 is configured to generate a pivoting load easing (PTLA) brake inhibit command 90 (see Figure 2A During the pivot turn maneuver 30, once one or more brake inhibit conditions 94 are satisfied, the PTLA brake inhibit subsystem 16 inhibits braking of one or more of the two or more wheels 46 of the pivoting main landing gear 32 and inhibits the brakes 58 via initiating 92 a pivot turn load alleviation (PTLA) brake inhibit command 90 to one or more brake control units 74 of the brake control system 14.

[0045] like Figure 2A As shown, one or more brake inhibit conditions 94 may include an aircraft on-ground state 96, which is indicated when the aircraft 10 is in an on-ground position 98 (i.e., the aircraft 10 is positioned in a ground position and not in the air, and is moving in a ground position). If the aircraft 10 is in the on-ground position 98, the brake inhibit condition 94 is satisfied or met. If the aircraft 10 is in the air, the brake inhibit condition 94 is not satisfied or met. The aircraft on-ground state 96 may be determined when the aircraft 10 is in the on-ground position 98, may be determined using an aircraft on-ground indication or sensor input, may be determined using a main landing gear fully extended indication or sensor input, may be determined using a tilt indication or sensor input of the wheel frame 44 of the main landing gear 24, may be determined using a shock strut squat switch or oil pressure indication or sensor input, or may be determined using another suitable indication or sensor input.

[0046] like Figure 2A As shown, one or more brake inhibiting conditions 94 may also include an acceptable aircraft ground speed 100, which is indicated when an aircraft ground speed 101 of the aircraft 10 is less than a pivot turn load alleviation (PTLA) speed threshold 104. In one exemplary version, the PTLA speed threshold 104 is 10 (ten) knots or less, and if the aircraft ground speed 101 is 11 (eleven) knots, the aircraft ground speed 101 exceeds the PTLA speed threshold 104 of 10 knots, and the brake inhibiting condition 94 is not met or not complied with. If the aircraft ground speed 101 is 9 (nine) knots, the aircraft ground speed 101 is less than the PTLA speed threshold 104 of 10 knots, and the brake inhibiting condition 94 is met or complied with. The acceptable aircraft ground speed 100 is preferably less than 2 (two) knots. The aircraft ground speed 101 used to determine the acceptable aircraft ground speed 100 may be determined from the average wheel speed 102 (see Figure 2A ), where average wheel speed means averaging all aircraft wheel speeds, may be estimated or determined from an Inertial Reference System (IRS) ground speed or acceleration, or may be estimated or determined using another suitable system or device.

[0047] like Figure 2A As shown, the one or more brake inhibition states 94 may also include a pivot turn load alleviation (PTLA) active flag command indication 106 generated by the monitoring logic 108 of the PTLA brake inhibition subsystem 16 to monitor the brake pedal position 110 according to one of a plurality of pivot turn brake pedal profiles 112 to detect the start 31 of the pivot turn maneuver 30. For example, the monitoring logic 108 monitors both the left brake pedal 64a and the right brake pedal 64b to detect and determine whether one or more pilots are starting or attempting a pivot turn maneuver 30. The monitoring logic output 108a (see FIG. 1 ) is determined based on the plurality of pivot turn brake pedal profiles 112. Figure 2A ), as described below Figures 4 to 7 If the monitoring logic 108 of the PTLA brake inhibition subsystem 16 detects the initiation 31 of the pivot turn maneuver 30 based on one of the plurality of pivot turn brake pedal profiles 112 , then the brake inhibition condition 94 is satisfied or met.

[0048] In one version, one or more of the braking inhibit conditions 94 include one braking inhibit condition 94 that is satisfied or met, wherein the one braking inhibit condition 94 includes the aircraft's on-ground state 96 or equivalent indication or sensor input, or an acceptable aircraft ground speed 100 or equivalent determination or estimate, or a PTLA active flag command indication 106. In another version, the braking inhibit conditions 94 may include two braking inhibit conditions 94 that are satisfied or met, wherein the two braking inhibit conditions 94 include a combination of the aircraft's on-ground state 96 and the PTLA active flag command indication 106, or an acceptable aircraft ground speed 100 and the PTLA active flag command indication 106, or an aircraft's on-ground state 96 and an acceptable aircraft ground speed 100, or another suitable combination. In another version, the braking inhibit conditions 94 may include three braking inhibit conditions 94 that are satisfied or met, wherein the three braking inhibit conditions 94 include the aircraft's on-ground state 96 or equivalent indication or sensor input, and an acceptable aircraft ground speed 100 or equivalent determination or estimate, and a PTLA active flag command indication 106.

[0049] Thus, when one or more of the brake inhibit conditions 94 are satisfied, met or detected, the PTLA brake inhibit subsystem 16 generates and initiates a PTLA brake inhibit command 90 (see FIG. Figure 2A ), and one or more brake control units 74 enable the PTLA brake inhibition command 90 to send the PTLA brake inhibition command 90 to the wheel selection 50 (see Figure 2A), for determining which of the two or more wheels 46 of the pivoting main landing gear 32 is to be inhibited, and inhibiting the braking of the wheel 46 in the wheel selection 50. Preferably, the PTLA brake inhibition command 90 is initiated very quickly after one or more of the brake inhibition conditions 94 are met or met, for example, within 100 ms (one hundred milliseconds) of the one or more brake inhibition conditions 94 being met or detected. The plurality of brake control units 74 receive the PTLA brake inhibition command 90 from the PTLA brake inhibition subsystem 16 and inhibit the generation of at least one brake command 76 (see Figure 2A ), the at least one braking command corresponding to at least one of the plurality of brake control valves 82 coupled to at least one wheel 46 in the unbraked state 52. Preferably, each time the left or right commanded brake pedal effort transitions from greater than 12% (twelve percent) to 8% (eight percent) of full brake pedal travel, for one or more wheels 46 to be restrained (see Figure 2A ) selection sequentially changes to the next round 46.

[0050] In one version, the wheel selection 50 may include an axle pair 48a of wheels 46 on the pivoting main landing gear 32, for example, an axle pair 48a of nose wheels 46c on the left main landing gear 24a (when the left main landing gear 24a is the pivoting main landing gear 32) or on the right main landing gear 24b (when the right main landing gear 24b is the pivoting main landing gear 32) (see FIG. FIG. 3A to FIG. 3C ) or axle pair 48a of rear wheel 46d (see FIG. 3A to FIG. 3C ). In this version, one axle pair 48a of wheel 46 will be inhibited once.

[0051] Preferably, the wheel selection 50 comprises a pair 48 of wheels 46, i.e. a common shaft 49 (see Figure 2A ) of the front wheel 46c (see FIG. 3A to FIG. 3C ) or rear wheel 46d (see FIG. 3A to FIG. 3C ), which are located on the four-wheel 46, two-axle 49 pivoting main landing gear 32 and are in the unbraked state 52 during the pivoting turning maneuver 30 (see Figure 2A ), and the other pair 48 of wheels 46 of the four-wheel 46, two-axle 49 pivoting main landing gear 32 is in a braking state 56 during the pivoting turning maneuver 30 (see Figure 2A ). In this version, for each subsequent pivoting maneuver 30a (see Figure 2A ), the wheel selection 50 of one axis pair 48a of the wheel 46 is in a sequential order 51 (see Figure 2A ) is changed to a different axis pair 48b of wheel 46 (see Figure 2A), such as the other axle pair 48a of the wheels 46. Preferably, whenever the left or right commanded brake pedal effort changes from greater than 12% (twelve percent) to 8% (eight percent) of full brake pedal travel, for the inhibited axle pair 48c (see Figure 2A ) selection is sequentially changed to the next axle pair 48a of the wheels 46. The percentage value corresponds to a standardized full brake pedal travel, for example, 0% is completely off the brake pedal and 100% is fully depressed.

[0052] In another version, where the pivoting main landing gear 32 has four wheels 46, the PTLA brake inhibit command 90 of the PTLA brake inhibit subsystem 16 may inhibit braking of one wheel 46, i.e., one wheel 46 on the pivoting main landing gear 32 is in the unbraked state 52 and three wheels 46 are in the braked state 56 during and during the pivoting turning maneuver 30 of the aircraft 10. In yet another version, where the pivoting main landing gear 32 has four wheels 46, the PTLA brake inhibit command 90 of the PTLA brake inhibit subsystem 16 may inhibit braking of three wheels 46, i.e., three wheels 46 on the pivoting main landing gear 32 are in the unbraked state 52 and one wheel 46 is in the braked state 56 during and during the pivoting turning maneuver 30 of the aircraft 10. In yet another version, where the pivoting main landing gear 32 has four wheels 46, the PTLA brake inhibit command 90 of the PTLA brake inhibit subsystem 16 may inhibit braking of two wheels 46 that are not wheels 46 of the axle pair 48a, for example, a front wheel 46c and a rear wheel 46d, or an inner wheel 46e (see Figure 2A ) or outer wheel 46f (see Figure 2A ), or two diagonal wheels 46i (see Figure 2A ) For example, two opposing corner wheels, during a pivoting turn maneuver 30 of the aircraft 10.

[0053] For the combination of the axle pair 48a of the wheel 46 of two diagonal wheels 46i, for example two opposite corner wheels, one pair of two diagonal wheels 46i is in the braking state 56, and the other pair of two diagonal wheels 46i is in the rolling state 53 (see Figure 2A ), the estimated reduction in torsional load reaction force 28b or torque load is about 9%. For the axle pair 48a combination of wheels 46, one of the front wheels 46c (see Figure 2A ) and a rear wheel 46d (see Figure 2A ) is in the braking state 56, while the other front wheel 46c and the other rear wheel 46d are in the rolling state 53, the estimated reduction in the torsional load reaction force 28b or torque load is about 18%. For the axle pair 48a combination of wheels 46, where the two front wheels 46c (see Figure 2A ) is in braking state 56, while the other two rear wheels 46d (see Figure 2A) is in the rolling state 53, the estimated reduction in torsional load reaction force 28b or torque load is approximately 13%. This alternative wheel pairing enables the use of the taxi brake release function 130 (see Figure 2A )integrated.

[0054] PTLA brake inhibit command 90 is used for pivot turn assist function 114 (see Figure 2A ), and can be in a brake control unit 74 (see Figure 2A ) or implemented in more than one brake control unit 74.

[0055] Furthermore, the PTLA brake inhibition subsystem 16 can be configured such that no single loss of function results in erroneous brake inhibition on both wheels 44, i.e., on the left and right wheels. Furthermore, no single loss of function, other than a loss of power to the brake control unit 74 of the brake control system 14, results in a loss of function on one of the main landing gears 24.

[0056] like Figure 2A As shown, when one or more brake inhibition deactivation conditions 118 are met or satisfied, the PTLA brake inhibition command 90 may undergo deactivation 116 and be removed. Figure 2A As shown, one or more brake inhibit deactivation conditions 118 may include an aircraft ground speed 101 of the aircraft 10 exceeding a pivot turn load alleviation (PTLA) speed threshold 104, for example, the aircraft ground speed 101 exceeding or greater than 10 (ten) knots. Figure 2A As shown, the one or more brake inhibition deactivation conditions 118 may also include two brake pedal commands 120, including a left brake pedal command 120a and a right brake pedal command 120b, exceeding a pivot turn load alleviation (PTLA) trigger brake pedal command threshold 122 for at least a predetermined time period 124. In one version, the predetermined time period 124 may be one (1) second after both the left brake pedal command 120a and the right brake pedal command 120b exceed the PTLA trigger brake pedal command threshold 122, for example, above a 50% command threshold. The predetermined time period 124, such as a one (1) second delay, is to ensure that the two brake pedal commands 120 (see Figure 2A ) is consistently above the PTLA trigger brake pedal command threshold 122, such as above the 50% command threshold, indicating to the pilot 154 (see Figure 2B ) is required to quickly stop the aircraft 10 or come to a complete stop. Once the predetermined time period 124 (e.g., one (1) second timer) has expired and both brake pedal commands 120 are above or exceed the PTLA trigger brake pedal command threshold 122, such as above the 50% command threshold, the remaining two brakes 58 that were inhibited will return to the commanded braking level.

[0057] like Figure 2A As shown, one or more brake inhibit deactivation conditions 118 may also include the aircraft 10 entering an active parking brake state 126 , ie, a parking brake 128 of the aircraft 10 being engaged, or becoming active.

[0058] In one version, one or more of the brake inhibit deactivation conditions 118 include a brake inhibit deactivation condition 118 being satisfied or met, wherein the brake inhibit deactivation condition 118 includes an aircraft ground speed 101 of the aircraft 10 exceeding a pivot turn load alleviation (PTLA) speed threshold 104, or two brake pedal commands 120 including a left brake pedal command 120a and a right brake pedal command 120b exceeding a PTLA trigger brake pedal command threshold 122 for at least a predetermined period of time 124, or the aircraft 10 entering an active parking brake state 126. In another version, the brake inhibition deactivation condition 118 may include two brake inhibition deactivation conditions 118 that are satisfied or met, wherein the two brake inhibition deactivation conditions 118 include a combination of the following: the aircraft ground speed 101 of the aircraft 10 exceeds the pivot turn load alleviation (PTLA) speed threshold 104, and the two brake pedal commands 120 including the left brake pedal command 120a and the right brake pedal command 120b exceed the PTLA trigger brake pedal command threshold 122 for at least a predetermined time period 124; or include a combination of the following: the aircraft 10 exceeds the PTLA speed threshold 104, and the aircraft 10 enters an active parking brake state 126; or include a combination of the following: the two brake pedal commands 120 including the left brake pedal command 120a and the right brake pedal command 120b exceed the PTLA trigger brake pedal command threshold 122 for at least a predetermined time period 124, and the aircraft 10 enters an active parking brake state 126. In another version, the brake inhibit deactivation conditions 118 may include three brake inhibit deactivation conditions 118 that are satisfied or met, wherein the three brake inhibit deactivation conditions 118 include the aircraft ground speed 101 of the aircraft 10 exceeding the pivot turn load alleviation (PTLA) speed threshold 104, and both brake pedal commands 120 including the left brake pedal command 120a and the right brake pedal command 120b exceed the PTLA trigger brake pedal command threshold 122 for at least a predetermined time period 124, and the aircraft 10 enters an active parking brake state 126.

[0059] like Figure 2AAs further shown, the aircraft 10 may optionally include a taxi brake release function 130. In the event that the aircraft 10 already includes a taxi brake release function 130, the PTLA brake inhibition subsystem 16 may be integrated with the taxi brake release function 130 to obtain a taxi brake release function integration 132. The taxi brake release function 130 may limit the brakes 58 to one or more but not all of the wheels 46. In one embodiment, the taxi brake release function 130 may limit the brakes 58 to a pair 48 (see FIG. Figure 2A ) wheel 46. The taxi brake release function 130 is a PTLA brake inhibition command 90 (see Figure 2A , FIG. 3A to FIG. 3C )Selection round selection 50 (see FIG. 3A to FIG. 3C ) to inhibit braking of one or more but not all wheels 46 of the pivoting main landing gear 32. In one embodiment, one or more but not all wheels 46 may be selected, such as wheel pairs, such as FIG. 3A to FIG. 3C , and discussed in further detail below, as it optionally enables integration of an existing taxi brake release function 130, also referred to as a taxi brake select function, and a PTLA brake inhibit command 90 function under the same PTLA brake inhibit subsystem 16 algorithm or programming logic.

[0060] The PTLA braking system 12 mitigates the loads 28 on the pivoting main landing gear 32 during a pivoting turning maneuver 30 of the aircraft 10 (see FIG. Figure 2A ), such as structural load 28a (see Figure 2A ), and reduces the braking of at least one wheel 46 in the unbraked state 52 (i.e., at least one unbraked wheel 46a with inhibited braking (see Figure 2A )) wear 136 (see Figure 2A ), and reduces wear 136 on the tires of the wheels 46. In addition, the PTLA braking system 12 inhibits braking on one or more brakes 58 on the pivoting main landing gear 32 to reduce the torsional load reaction force 28b (see Figure 2A ). The PTLA braking system 12 can also reduce the steering force 134 (see Figure 2A ), which in turn reduces wear 136. The PTLA braking system 12 can also provide U-turn optimization 138 (see Figure 2A). The PTLA braking system 12 may also reduce the overall weight of the main landing gear 24 because, with the reduced structural loads 28a and reduced steering forces 134, various components and materials on the main landing gear 24 may be reduced or eliminated, such as a smaller weight-reducing scissor link, a smaller weight-reducing torque link, or another small size structure on the main landing gear 24, such as a pivoting main landing gear 32. The potential to reduce the weight of the main landing gear 24 of the aircraft 10 may save at least twenty-five pounds (25 lbs) of weight or more.

[0061] Reference now Figure 2B , Figure 2B is an illustration of a functional block diagram showing a system having multiple PTLA entry scenarios 140 and multiple PTLA exit scenarios 142. Figure 2A The aircraft 10 and the PTLA braking inhibition subsystem 16. Figure 2B As further shown, the PTLA braking system 12 includes a braking control system 14 and a PTLA braking inhibition subsystem 16 that monitors a PTLA entry scene 140 and a PTLA exit scene 142. Figures 4 to 7 As shown and discussed in further detail below, the monitoring logic 108 (see Figure 2A ) monitors and senses each pivot turn brake pedal curve 112 (see Figure 2B ) to detect and determine the pivot turn maneuver 30 (see Figure 2B )31 (see Figure 2A ), each pivot turn brake pedal curve represents one of the PTLA entry scenarios 140 and one of the PTLA exit scenarios 142. Each of the PTLA entry scenarios 140 and each of the PTLA exit scenarios 142 includes an initial state 144 (see Figure 2B ), state change 146 (see Figure 2B ) and result 148 (see Figure 2B ).

[0062] Next, the pivot turn maneuver 30 (see Figure 2B ) or pivoting to become a pivoting main landing gear 32 (see Figure 2B ) of a main landing gear 24 (see Figure 2B ) side A 150 (see Figure 2B ) and B side 152 (see Figure 2B ) to describe three (3) exemplary PTLA entry scenarios 140, wherein the brake pedal 64 (see Figure 2B ) is connected to a main landing gear 24, and four wheels 46 of a main landing gear 24 (see Figure 2B ) has a brake 58 (see Figure 2B ). The three (3) exemplary PTLA entry scenarios 140 are summarized as follows:

[0063] (1) The first PTLA enters scene 140a (see Figure 2B ) includes: (a) an initial state 144 with no brake 58 applied / acting on side A and no brake 58 applied / acting on side B, wherein the aircraft ground speed 101 (see Figure 2B ) is below the PTLA speed threshold 104 (see Figure 2B ), for example, by using the average wheel speed 102 (see Figure 2B ) determined by the pilot; (b) pilot 154 (see Figure 2B ) The brake pedal 64 is applied on the A side and the brake pedal 64 is not applied on the B side. The state change 146, wherein the aircraft ground speed 101 (see Figure 2B ) is below the PTLA speed threshold 104, for example, as determined using the average wheel speed 102; and (c) one or more brakes 58 on the A side are applied / applied and one or more brakes 58 on the B side are in the inhibited state 57 (see Figure 2B ) of the restraining brake 58a (see Figure 2B ) result 148, and no brake 58 is applied on the B side, and where the aircraft ground speed 101 (see Figure 2B ) is below a PTLA speed threshold 104 , for example, as determined using average wheel speed 102 .

[0064] (2) The second PTLA enters scene 140b (see Figure 2B ) includes: (a) an initial state 144 with the brake 58 applied / acting on the A side and the brake 58 applied / acting / acting on the B side, wherein the aircraft ground speed 101 (see Figure 2B ) is below the PTLA speed threshold 104, for example, as determined using the average wheel speed 102; (b) the pilot releases the brake pedal 64 on the B side, and the brake pedal 64 on the B side is still applied and remains depressed 146, wherein the aircraft ground speed 101 (see Figure 2B ) is below the PTLA speed threshold 104, for example, as determined using the average wheel speed 102; and (c) the result 148 that one or more brakes 58 on side A are still applied, and all brakes 58 on side B and one or more brakes 58 on side A are released, such that the one or more brakes 58 on side A that are released are the inhibiting brakes 58a that are in the inhibited state 57, and wherein the aircraft ground speed 101 (see Figure 2B ) is below a PTLA speed threshold 104 , for example, as determined using average wheel speed 102 .

[0065] (3) The third PTLA enters scene 140c (see Figure 2B) includes: (a) an initial state 144 with brake 58 applied / applied on side A and no brake 58 applied / applied on side B, wherein the aircraft ground speed 101 (see Figure 2B ) is above the PTLA speed threshold 104, for example, as determined using the average wheel speed 102; (b) a state change 146 of the aircraft 10 decelerating so that the aircraft ground speed 101 (see Figure 2B ) is below the PTLA speed threshold 104, e.g., as determined using the average wheel speed 102, and the brake pedal 64 on the B side is still applied / applied and remains depressed, while the brake pedal 64 on the B side is not applied; and (c) no brakes 58 on the B side are applied / applied, and one or more brakes 58 on the A side are released 148, such that the one or more brakes 58 on the A side that are released are the inhibited brakes 58a that are in the inhibited state 57, and wherein the aircraft ground speed 101 (see Figure 2B ) is below a PTLA speed threshold 104 , for example, as determined using average wheel speed 102 .

[0066] Next, the pivot turn maneuver 30 or pivot turn is used to pivot the main landing gear 32 (see Figure 2B ) to describe three (3) exemplary PTLA exit scenarios 142 (see FIG. Figure 2B ), wherein the brake pedal 64 is connected to one main landing gear 24, and two or more wheels 46, such as four wheels 46 of one main landing gear 24 have brakes 58. The three (3) exemplary PTLA exit scenarios 142 are summarized as follows:

[0067] (1) First PTLA exit scene 142a (see Figure 2B ) includes: (a) one or more brakes 58 on side A are applied / applied and are restraining brakes 58a in restraining state 57, and an initial state 144 with no brakes 58 applied / applied on side B, wherein the aircraft ground speed 101 (see Figure 2B ) is below the PTLA speed threshold 104, for example, as determined using the average wheel speed 102; (b) the pilot releases the brake pedal 64 on side A, while the brake pedal 64 on side B is not applied, and the aircraft ground speed 101 (see Figure 2B ) is below the PTLA speed threshold 104, for example, as determined using the average wheel speed 102; and (c) a result 148 where no brakes 58 are applied / applied on the A side and no brakes 58 are applied / applied on the B side, wherein the aircraft ground speed 101 (see Figure 2B ) is below a PTLA speed threshold 104 , for example, as determined using average wheel speed 102 .

[0068] (2) Second PTLA exit scene 142b (see Figure 2B ) includes: (a) one or more brakes 58 on side A are applied / applied and are restraining brakes 58a in restrained state 57, and an initial state 144 with no brakes 58 applied / applied on side B, wherein the aircraft ground speed 101 (see Figure 2B ) is below the PTLA speed threshold 104, for example, as determined using the average wheel speed 102; (b) the pilot applies the brake pedal 64 on the B side, and the brake pedal 64 on the A side remains depressed, a change in state 146, wherein the aircraft ground speed 101 (see Figure 2B ) is below the PTLA speed threshold 104, for example, as determined using the average wheel speed 102; and (c) all (all) brakes 58 on the A side are applied / applied and all (all) brakes 58 on the B side are applied / applied, wherein the aircraft ground speed 101 (see Figure 2B ) is below a PTLA speed threshold 104 , for example, as determined using average wheel speed 102 .

[0069] (3) Third PTLA exit scenario 142c (see Figure 2B ) includes: (a) one or more brakes 58 on side A are applied / applied and are restraining brakes 58a in restrained state 57, and an initial state 144 with no brakes 58 applied / applied on side B, wherein the aircraft ground speed 101 (see Figure 2B ) is below the PTLA speed threshold 104, for example, as determined using the average wheel speed 102; (b) the aircraft 10 is accelerated and the state change 146 is such that the aircraft ground speed 101 (see Figure 2B ) is above the PTLA speed threshold 104, e.g., as determined using the average wheel speed 102, and the brake pedal 64 on the B side is still applied / applied and remains depressed, while the brake pedal 64 on the B side is not applied; and (c) all (all) brakes 58 on the A side are applied / applied, and no brakes 58 on the B side are applied / applied 148, where the aircraft ground speed 101 (see Figure 2B ) is above the PTLA speed threshold 104, for example, as determined using the average wheel speed 102.

[0070] Utilizing the multiple PTLA entry scenarios 140 and multiple PTLA exit scenarios 142 discussed above, the brakes 46 may be released based on the taxi brake release function 130 (see Figure 2A ) is limited to one or more but not all of the brakes 46, and no brakes being applied may mean that the brakes are below a certain pedal threshold, such as the minimum PTLA trigger brake pedal command threshold 122a (see Figure 4), for example, 25% of the pilot's brake pedal effort (see Figures 4 to 7 ). Additionally, using the multiple PTLA entry scenarios 140 and multiple PTLA exit scenarios 142 discussed above, the applied or applied pedal may mean that the brake 58 exceeds a particular pedal threshold, such as the maximum PTLA trigger brake pedal command threshold 122b (see Figure 4 ), for example 27% of the pilot's brake pedal effort (see Figures 4 to 7 ), and releasing the pedal may mean that the brake 58 is below the minimum PTLA trigger brake pedal command threshold 122a (see Figure 4 ), for example 25% of the pilot's brake pedal effort (see Figures 4 to 7 ). In addition, the differential wheel speed between the left main landing gear 24a and the right main landing gear 24b can be considered to obtain a more accurate start-up criterion. In addition, a second threshold value can be used to ensure that the pivot turn command is intended or not intended, and a delay function can be used to ensure that the brake pedal command 120 is intended to execute the scheme, i.e., the pivot turn. The percentage value corresponds to a normalized full brake pedal travel, for example, 0% is completely off the brake pedal and 100% is fully depressed.

[0071] like Figure 1A to Figure 1B and Figure 2A As shown, in another version of the present disclosure, a body 18 (see Figure 1A to Figure 1B ), one or more wings 20 attached to the fuselage 18 (see Figure 1A to Figure 1B ), and a plurality of landing gears 22 attached to the fuselage 18 (see Figure 1A to Figure 1B ) of an aircraft 10. A plurality of landing gears 22 include a front landing gear 26 (see Figure 1A to Figure 1B ) and at least two main landing gears 24 (see Figure 1A to Figure 1B , Figure 2A ), each of at least two main landing gears 24 has two or more wheels 46 (see Figure 1A to Figure 1B , Figure 2A ), wherein during the pivot turn maneuver 30 of the aircraft 10 (see Figure 2A ) during which at least one of the two main landing gears 24 includes a pivoting main landing gear 32 (see Figure 2A Each main landing gear 24 may have, for example, two wheels, four wheels, six wheels, or another suitable number of wheels.

[0072] The aircraft 10 also includes a PTLA braking system 12 including a brake control system 14 operably coupled to at least two main landing gears 24, wherein the brake control system 14 controls braking of the at least two main landing gears 24. The PTLA system also includes a PTLA brake inhibition subsystem 16 coupled to the brake control system 14, wherein the PTLA brake inhibition subsystem 16 inhibits braking of one or more of two or more wheels 46 of one main landing gear 24 including the pivoting main landing gear 32 during the pivoting turning maneuver 30 such that at least one wheel 46 of the two or more wheels 46 is in an unbraked state 52 and a remaining number 54 of the two or more wheels 46 is in a braked state 56. As described above, the PTLA braking system 12 mitigates structural loads 28a on the pivoting main landing gear 32 during the pivoting turning maneuver 30 of the aircraft 10 and reduces wear 136 on the at least one wheel 46 in the unbraked state 52.

[0073] Once the brake inhibition state 94 (see Figure 2A ), the PTLA brake inhibition subsystem 16 sends a signal to one or more brake control units 74 (see Figure 2A ) Start 92PTLA brake inhibition command 90 (see Figure 2A As described above, one or more braking inhibition conditions 94 include one or more of the following: (a) the aircraft's on-ground state 96 (see Figure 2A ), which is indicated when the aircraft 10 is at the on-ground position 98; (b) an acceptable aircraft ground speed 100 (see Figure 2A ), which is at the aircraft ground speed 101 of the aircraft 10 (see Figure 2A ) is less than the PTLA speed threshold 104; or (c) by the monitoring logic 108 of the PTLA brake inhibition subsystem 16 (see Figure 2A ) generates a PTLA active flag command indication 106 (see Figure 2A ) to monitor the brake pedal position 110 (see Figure 2A ) to adjust the brake pedal according to one of the plurality of pivoting turn brake pedal curves 112 (see Figure 2A ) detects the start 31 of the pivot turn maneuver 30.

[0074] When the brake inhibition deactivation condition 118 (see Figure 2A ), the PTLA brake inhibit command 90 is deactivated when one or more of the following conditions are met: (a) the aircraft ground speed 101 of the aircraft 10 exceeds the PTLA speed threshold 104; (b) the left brake pedal command 120a (see Figure 2A) and right brake pedal command 120b (see Figure 2A ) both exceed the PTLA trigger brake pedal command threshold 122 (see Figure 2A ) for at least a predetermined period of time 124 (see Figure 2A ); or (c) the aircraft 10 enters the active parking brake state 126 (see Figure 2A ).

[0075] In one version, the aircraft 10 may also include a taxi brake release function 130 , and the PTLA brake inhibit subsystem 16 is integrated with the taxi brake release function 130 , which executes the PTLA brake inhibit command 90 on behalf of the PTLA brake inhibit subsystem 16 to inhibit braking of one or more but not all wheels 46 of the pivoting main landing gear 32 .

[0076] Reference now FIG. 3A to FIG. 3C , Figure 3A is an illustration of a schematic diagram of a PTLA braking system command logic diagram 156a during a pivot turn maneuver 30 of an aircraft 10, Figure 3B is an illustration of a schematic diagram of another version of the PTLA brake system command logic diagram 156b, Figure 3C is an illustration of a schematic diagram of yet another version of the PTLA brake system command logic diagram 156c.

[0077] Figure 3A 156a, wherein the brake inhibit condition 94 includes a brake inhibit condition 94 including a PTLA active flag command (CMD) indication 106 that initiates the PTLA brake inhibit command 90 to cause a PTLA brake inhibit command (CMD) enable function 158, wherein the brake control unit 74 (see FIG. 156b ) of the brake control system 14 Figure 2A ) enables the PTLA brake inhibit command 90. The PTLA active flag command indication 106 is provided by the monitoring logic 108 (see Figure 2A ) is generated, the monitoring logic 108 determines that the pilot 154 (see Figure 2B ) is attempting a pivot turn maneuver 30, and based on the pivot turn brake pedal curve 112 (see FIG. 2A to FIG. 2B , Figures 4 to 7 ) to determine the monitoring logic output 108a (see Figure 2A ).

[0078] Figure 3BA PTLA brake system command logic diagram 156b is shown, wherein the brake inhibit condition 94 includes two brake inhibit conditions 94, the two brake inhibit conditions 94 including either of the following: (a) the aircraft's on-ground status 96 and a PTLA active flag command (CMD) indication 106, or (b) an acceptable aircraft ground speed 100 and a PTLA active flag command (CMD) indication 106, either combination of which initiates the PTLA brake inhibit command 90. This results in a PTLA brake inhibit command (CMD) enable function 158, wherein the brake control unit 74 (see Figure 2A ) enables the PTLA brake inhibit command 90. The PTLA active flag command indication 106 is provided by the monitoring logic 108 (see Figure 2A ) is generated, the monitoring logic 108 determines that the pilot 154 (see Figure 2B ) is attempting a pivot turn maneuver 30, and based on the pivot turn brake pedal curve 112 (see FIG. 2A to FIG. 2B , Figures 4 to 7 ) to determine the monitoring logic output 108a (see Figure 2A ).

[0079] Figure 3C 156b, wherein the brake inhibit condition 94 includes all of the following: (a) the aircraft on-ground state 96, (b) an acceptable aircraft ground speed 100, and (c) a PTLA active flag command (CMD) indication 106 to initiate or generate the PTLA brake inhibit command 90. This results in a PTLA brake inhibit command (CMD) enable function 158, wherein the brake control system 14 (see Figure 2A ) of the brake control unit 74 enables the PTLA brake inhibit command 90. The PTLA active flag command indication 106 is generated by the monitoring logic 108 (see Figure 2A ) is generated, the monitoring logic 108 determines that the pilot 154 (see Figure 2B ) is attempting a pivot turn maneuver 30, and based on the pivot turn brake pedal curve 112 (see FIG. 2A to FIG. 2B , Figures 4 to 7 ) to determine the monitoring logic output 108a (see Figure 2A ).

[0080] like FIG. 3A to FIG. 3C As shown, the PTLA brake inhibit command (CMD) enabling function 158 is executed, wherein the brake control unit 74 (see Figure 2A ) enables the PTLA brake inhibit command 90 to cause a PTLA brake inhibit command (CMD) enable 160 to be sent to the wheel select function 162. FIG. 3A to FIG. 3CAs further shown in FIG. 1 , if the PTLA brake inhibit command 90 is present and exists on the aircraft 10 (see FIG. Figure 1A to Figure 1B , Figure 2A ), the PTLA brake inhibition command 90 may optionally be integrated with the taxi brake release function 130 to obtain a taxi brake release function integration 132. FIG. 3A to FIG. 3C As shown, when the current taxi brake release selection 164 is already present and presented on the aircraft 10, the current taxi brake release selection 164 can be optionally selected to select the wheel X 166 in the number 1 position 168 corresponding to the forward outboard wheel position number 1 168a of the wheel 46 of the left main landing gear 24a, in this case, the pivoting main landing gear 32. FIG. 3A to FIG. 3C As shown, the current taxi brake release selection 164 further selects wheel Y 170 in number 2 position 172 corresponding to forward outboard wheel position number 2 172a of wheel 46 of left main landing gear 24a. FIG. 3A to FIG. 3C The left main landing gear 24a having four wheels 46 and the right main landing gear 24b having four wheels 46 are shown. Wheel X 166 and wheel Y 170 are the axle pair 48a of wheels 46 (see FIG. FIG. 3A to FIG. 3C ). The PTLA brake inhibit command 90 inhibits the braking of wheel X 166 and wheel Y 170, and the wheel X, Y inhibit command (CMD) 174 (see FIG. 3A to FIG. 3C ) is sent to the brake control unit command (CMD) to generate 176. FIG. 3A to FIG. 3C As shown, brake control unit command generation 176 also receives a pilot pedal command (CMD) 178 and a hardware (HW) enable command (CMD) 180 .

[0081] like FIG. 3A to FIG. 3C As shown, the brake control unit command generation 176 then sends a wheel X inhibit command (CMD) 182 and a wheel Y inhibit command (CMD) 184 to the brake control valves 82. One brake control valve 82 is coupled or connected to wheel X 166 via a first hydraulic connector element 88a to inhibit braking of wheel X 166 on the left main landing gear 24a, while the other brake control valve 82 is coupled or connected to wheel Y 170 via a second hydraulic connector element 88b to inhibit braking of wheel Y 170 on the left main landing gear 24a. FIG. 3A to FIG. 3C As shown, the PTLA brake inhibit command 90, in conjunction with the brake control unit 74 and the brake control valve 82, causes the paired wheels 46h on the pivoting main landing gear 32 to be inhibited. FIG. 3A to FIG. 3C As shown, no wheels are restrained on the right main landing gear 24b which is the non-pivoting main landing gear 34.

[0082] Reference now Figure 4 , Figure 41 is an illustration of a graph 186 showing a pivot turn brake pedal curve 112 in the form of an exemplary first pivot turn brake pedal curve 112a, wherein the pivot turn maneuver 30 is entered in the form of a left pivot turn maneuver 30b for both initial and end scenarios with both pedals depressed 190. Figure 4 As shown, the graph 186 includes a first portion 192, wherein the pilot brake pedal force 193 is expressed as a percentage (%) on the y-axis and the time 194 is expressed in seconds (s) on the x-axis. The percentage value corresponds to a normalized full brake pedal travel, for example, 0% is completely released from the brake pedal and 100% is fully depressed. Figure 4 As further shown, the graph 186 includes a second portion 196 having a pivot turn marker 198 on the y-axis and also having a time 194 in seconds (s) on the x-axis, and a first inactive portion 200, an active portion 202, and a second inactive portion 204 along the x-axis. Figure 4 As further shown, the graph 186 includes a third portion 206 that illustrates the braking state 208 of the wheels 46 on the left main landing gear 24a and the right main landing gear 24b. Figure 4 As further shown, the braking state 208 includes no brake 210 , brake applied 212 , and brake inhibited—no brake 214 .

[0083] like Figure 4 As shown, when entering the left pivot turn maneuver 188 turns into entering and exiting the pivot turn with braking, the first portion 192 shows a left pedal plot 216 of the left pedal 218 and a right pedal plot 220 of the right pedal 222 is shown through the first inactive portion 200, the active portion 202 and the second inactive portion 204. The first portion 192 also shows a hysteresis 224, which has a minimum PTLA trigger brake pedal command threshold 122a and a maximum PTLA trigger brake pedal command threshold 122b. As used herein, "hysteresis" refers to an output selection where the output command changes at different thresholds depending on the direction the input command is traveling. If the input signal, such as a brake pedal command, oscillates from one fixed threshold to another fixed threshold, such hysteresis is used in the control function to avoid limit cycle effects in the output command.

[0084] like Figure 4 As shown, during the first inactive portion 200, both the left pedal 218 and the right pedal 220 are initially depressed and the wheels 46 of the left main landing gear 24a and the right main landing gear 24b are in the brake applied 212 braking state 208. Figure 4As further shown, during the active portion 202, the left pedal 218 is held depressed and the right pedal 222 is released, and the wheels 46 of the right main landing gear 24b are in the brakeless 210 braking state 208. Figure 4 As shown, when the right pedal curve 220 drops below the minimum PTLA triggering brake pedal command threshold 122a (and the average wheel speed 102 (see Figure 2A ) is less than the PTLA speed threshold 104 (see Figure 2A )), the PTLA brake inhibition command 90 is activated and enters PTLA, and the PTLA brake inhibition command 90 (see Figure 2A , FIG. 3A to FIG. 3C ) is sent to the brake control unit 74 (see FIG. 3A to FIG. 3C ) and round selection 50 (see FIG. 3A to FIG. 3C ) to inhibit the brakes 58 on the pair of wheels 48 46 on the left main landing gear 24a (see Figure 2A ).like Figure 4 As shown, during the active portion 202, the pair 48 of front wheels 46c on the left main landing gear 24a is in the brake-disabled-brake 214 braking state 208, while the pair 48 of rear wheels 46d on the left main landing gear 24a is in the brake-applied 212 braking state 208. Note that the pair 48 of rear wheels 46d may be restrained instead of the pair 48 of front wheels 46c on the left main landing gear 24a, or other combinations of restrained wheels 46, such as the diagonal wheels 46i (see Figure 2A ), one wheel 46, three wheels 46, or other suitable number of wheels.

[0085] like Figure 4 As shown, when the right pedal graph 220 exceeds the maximum PTLA triggering brake pedal command threshold 122b for transitioning from the active portion 202 to the second inactive portion 204, the PTLA brake inhibit command 90 is deactivated, and in the second inactive portion 204, the left pedal 218 remains depressed and applied, and the right pedal 222 is applied, thereby generating an all brakes applied state 226 when PTLA is exited. Figure 4 As shown, during the second inactive portion 204, all wheels 46 on the left main landing gear 24a and the right main landing gear 24b are in the brake applied 212 braking state 208.

[0086] Reference now Figure 5 , Figure 52 is an illustration of a graph 228 showing a pivot turn brake pedal curve 112 in the form of an exemplary second pivot turn brake pedal curve 112b, wherein the pivot turn maneuver 30 in the form of a left pivot turn maneuver 30b is entered for both pedals initially depressed and released 230 for the end scenario into the left pivot turn maneuver 188. Figure 5 As shown, the graph 228 includes a first portion 192, wherein the pilot brake pedal force 193 is expressed as a percentage (%) on the y-axis and the time 194 is expressed in seconds (s) on the x-axis. The percentage value corresponds to a normalized full brake pedal travel, for example, 0% is completely released from the brake pedal and 100% is fully depressed. Figure 5 As further shown, the graph 228 includes the second portion 196, with the pivot turn index 198 on the y-axis, the time 194 in seconds (s) on the x-axis, and a first inactive portion 200, an active portion 202, and a second inactive portion 204 along the x-axis. Figure 5 As further shown, the graph 228 includes a third portion 206 that illustrates the braking state 208 of the wheels 46 on the left main landing gear 24a and the right main landing gear 24b. Figure 5 As further shown, the braking state 208 includes no brake 210 , brake applied 212 , and brake inhibited—no brake 214 .

[0087] like Figure 5 As shown, when entering the left pivot turn maneuver 188 transitions into and out of the braking pivot turn, the first portion 192 shows a left pedal graph 216a of the left pedal 218 and a right pedal graph 220a of the right pedal 222 through the first inactive portion 200, the active portion 202, and the second inactive portion 204. The first portion 192 also shows a hysteresis 224 having a minimum PTLA triggering brake pedal command threshold 122a and a maximum PTLA triggering brake pedal command threshold 122b.

[0088] like Figure 5 As shown, during the first inactive portion 200, both the left pedal 218 and the right pedal 220 are initially depressed and the wheels 46 of the left main landing gear 24a and the right main landing gear 24b are in the brake applied 212 braking state 208. Figure 5 As further shown, during the active portion 202, the left pedal 218 is depressed and the right pedal 222 is released, and the wheels 46 of the right main landing gear 24b are in the brakeless 210 braking state 208. Figure 5As shown, when the right pedal curve 220a drops below the minimum PTLA triggering brake pedal command threshold 122a (and the average wheel speed 102 (see Figure 2A ) is less than the PTLA speed threshold 104 (see Figure 2A )), the PTLA brake inhibition command 90 is activated and enters PTLA, and the PTLA brake inhibition command 90 (see Figure 2A , FIG. 3A to FIG. 3C ) is sent to the brake control unit 74 (see FIG. 3A to FIG. 3C ) and round selection 50 (see FIG. 3A to FIG. 3C ) to inhibit the brakes 58 on the pair of wheels 48 46 on the left main landing gear 24a (see Figure 2A ).like Figure 5 As shown, during the active portion 202, the pair 48 of rear wheels 46d on the left main landing gear 24a is in the brake-disabled-brake 214 braking state 208, while the pair 48 of front wheels 46c on the left main landing gear 24a is in the brake-applied 212 braking state 208. Note that the pair 48 of front wheels 46c may be restrained instead of the pair 48 of rear wheels 46d on the left main landing gear 24a, or other combinations of restrained wheels 46, such as the diagonal wheels 46i (see Figure 2A ), one wheel 46, three wheels 46, or other suitable number of wheels.

[0089] like Figure 5 As shown, when the left pedal curve 216a is below the minimum PTLA trigger brake pedal command threshold 122a for transitioning from the active portion 202 to the second inactive portion 204, the PTLA brake inhibit command 90 is deactivated, and in the second inactive portion 204, the left pedal 218 is released and the right pedal 222 remains released, so that all wheels 46 on the left main landing gear 24a and the right main landing gear 24b are in a brake-free 210 braking state 208 when PTLA is exited.

[0090] Reference now Figure 6 , Figure 6 2 is an illustration of a graph 232 showing a pivot turn brake pedal curve 112 in the form of an exemplary third pivot turn brake pedal curve 112c, wherein entry into the left pivot turn maneuver 188 in the form of a left pivot turn maneuver 30b is performed with no pedal initially depressed and both pedals depressed 234 for an end scenario. Figure 6As shown, the graph 232 includes a first portion 192, wherein the pilot brake pedal force 193 is expressed as a percentage (%) on the y-axis and the time 194 is expressed in seconds (s) on the x-axis. The percentage value corresponds to a normalized full brake pedal travel, for example, 0% is completely released from the brake pedal and 100% is fully depressed. Figure 6 As further shown, the graph 232 includes a second portion 196 with a pivot turn indicator 198 on the y-axis, a time 194 in seconds (s) on the x-axis, and a first inactive portion 200, an active portion 202, and a second inactive portion 204 along the x-axis. Figure 6 As further shown, the graph 228 includes a third portion 206 that illustrates the braking state 208 of the wheels 46 on the left main landing gear 24a and the right main landing gear 24b. Figure 6 As further shown, the braking state 208 includes no brake 210 , brake applied 212 , and brake inhibited—no brake 214 .

[0091] like Figure 6 As shown, when entering the left pivot turn maneuver 188 transitions into and out of the braking pivot turn, the first portion 192 shows a left pedal graph 216b for the left pedal 218 and a right pedal graph 220b for the right pedal 222 through the first inactive portion 200, the active portion 202, and the second inactive portion 204. The first portion 192 also shows a hysteresis 224 having a minimum PTLA triggering brake pedal command threshold 122a and a maximum PTLA triggering brake pedal command threshold 122b.

[0092] like Figure 6 As shown, during the first inactive portion 200, both the left pedal 218 and the right pedal 216 are initially not depressed, and the wheels 46 of the left main landing gear 24a and the right main landing gear 24b are in the brakeless 210 braking state 208. Figure 6 As further shown, during the active portion 202, the left pedal 218 is applied and depressed, and the right pedal 222 is not applied and depressed, and the wheel 46 of the right main landing gear 24b is in the brakeless 210 braking state 208. Figure 6 As shown, when the left pedal curve 216b exceeds the maximum PTLA triggering brake pedal command threshold 122b (and the average wheel speed 102 (see Figure 2A ) is less than the PTLA speed threshold 104 (see Figure 2A )), the PTLA brake inhibition command 90 is activated and enters PTLA, and the PTLA brake inhibition command 90 (see Figure 2A , FIG. 3A to FIG. 3C) is sent to the brake control unit 74 (see FIG. 3A to FIG. 3C ) and round selection 50 (see FIG. 3A to FIG. 3C ) to inhibit the brakes 58 on the pair of wheels 48 46 on the left main landing gear 24a (see Figure 2A ).like Figure 6 As shown, during the active portion 202, the pair 48 of front wheels 46c on the left main landing gear 24a is in the brake-disabled-brake 214 braking state 208, while the pair 48 of rear wheels 46d on the left main landing gear 24a is in the brake-applied 212 braking state 208. Note that the pair 48 of rear wheels 46d may be restrained instead of the pair 48 of front wheels 46c on the left main landing gear 24a, or other combinations of restrained wheels 46, such as the diagonal wheels 46i (see Figure 2A ), one wheel 46, three wheels 46, or other suitable number of wheels.

[0093] like Figure 6 As shown, when the right pedal graph 220b exceeds the maximum PTLA triggering brake pedal command threshold 122b for transitioning from the active portion 202 to the second inactive portion 204, the PTLA brake inhibit command 90 is deactivated, and in the second inactive portion 204, the left pedal 218 remains depressed and applied, and the right pedal 222 is depressed and applied, resulting in an all brakes applied state 226 when PTLA is exited. Figure 6 As shown, during the second inactive portion 204, all wheels 46 on the left main landing gear 24a and the right main landing gear 24b are in the brake applied 212 braking state 208.

[0094] Reference now Figure 7 , Figure 7 2 is an illustration of a graph 236 showing the pivot turn brake pedal curve 112 in the form of an exemplary fourth pivot turn brake pedal curve 112d, wherein entry into the left pivot turn maneuver 188 in the form of the left pivot turn maneuver 30b is performed with no pedal initially depressed and then with both pedals released 238 for an ending scenario. Figure 7 As shown, the graph 232 includes a first portion 192, wherein the pilot brake pedal force 193 is expressed as a percentage (%) on the y-axis and the time 194 is expressed in seconds (s) on the x-axis. The percentage value corresponds to a normalized full brake pedal travel, for example, 0% is completely released from the brake pedal and 100% is fully depressed. Figure 7 As further shown, the graph 232 includes a second portion 196 with a pivot turn indicator 198 on the y-axis, a time 194 in seconds (s) on the x-axis, and a first inactive portion 200, an active portion 202, and a second inactive portion 204 along the x-axis. Figure 7 As further shown, the graph 228 includes a third portion 206 that illustrates the braking state 208 of the wheels 46 on the left main landing gear 24a and the right main landing gear 24b. Figure 7 As further shown, the braking state 208 includes no brake 210 , brake applied 212 , and brake inhibited—no brake 214 .

[0095] like Figure 7 As shown, when entering the left pivot turn maneuver 188 transitions into and out of the braking pivot turn, the first portion 192 shows a left pedal graph 216c for the left pedal 218 and a right pedal graph 220c for the right pedal 222 through the first inactive portion 200, the active portion 202, and the second inactive portion 204. The first portion 192 also shows a hysteresis 224 having a minimum PTLA triggering brake pedal command threshold 122a and a maximum PTLA triggering brake pedal command threshold 122b.

[0096] like Figure 7 As shown, during the first inactive portion 200, both the left pedal 218 and the right pedal 220 are initially not depressed, and the wheels 46 of the left main landing gear 24a and the right main landing gear 24b are in the brakeless 210 braking state 208. Figure 7 As further shown, during the active portion 202, the left pedal 218 is applied and depressed, and the right pedal 222 is not applied and depressed, and the wheel 46 of the right main landing gear 24b is in the brakeless 210 braking state 208. Figure 7 As shown, when the left pedal curve 216c exceeds the maximum PTLA triggering brake pedal command threshold 122b (and the average wheel speed 102 (see Figure 2A ) is less than the PTLA speed threshold 104 (see Figure 2A )), the PTLA brake inhibition command 90 is activated and enters PTLA, and the PTLA brake inhibition command 90 (see Figure 2A , FIG. 3A to FIG. 3C ) is sent to the brake control unit 74 (see FIG. 3A to FIG. 3C ) and round selection 50 (see FIG. 3A to FIG. 3C ) to inhibit the brakes 58 on one or more but not all wheels 46 (see Figure 2A ), for example, to inhibit the brakes 58 on the pair 48 of wheels 46 on the left main landing gear 24a. Figure 7As shown, during the active portion 202, one or more but not all wheels 46 on the left main landing gear 24a, such as the pair 48 rear wheels 46d, are in the brake inhibited-no brake 214 braking state 208, and one or more but not all wheels 46 on the left main landing gear 24a, such as the pair 48 front wheels 46c, are in the brake applied 212 braking state 208. It should be noted that one or more but not all wheels 46, such as the pair 48 front wheels 46c, may be inhibited instead of one or more but not all wheels 46 on the left main landing gear 24a, such as the pair 48 rear wheels 46d, or other combinations of inhibited wheels 46, such as the diagonal wheels 46i (see Figure 2A ), one wheel 46, three wheels 46, or other suitable number of wheels.

[0097] like Figure 7 As shown, when the left pedal curve 216c is below the minimum PTLA trigger brake pedal command threshold 122a for transitioning from the active portion 202 to the second inactive portion 204, the PTLA brake inhibit command 90 is deactivated, and in the second inactive portion 204, the left pedal 218 is released and the right pedal 222 remains released, so that all wheels 46 on the left main landing gear 24a and the right main landing gear 24b are in a braking state 208 without brakes 210.

[0098] Reference now Figure 8 , Figure 8 is an illustration of a flow chart showing an exemplary version of a method 250 of the present disclosure. In another version of the present disclosure, a method for performing a pivot turn maneuver 30 (see Figure 2A ) and slowing down the aircraft 10 during neutralization (see Figure 1A to Figure 1B , Figure 2A ) of the pivoting main landing gear 32 (see Figure 2A ) on the structural load 28a (see Figure 2A ) method 250 (see Figure 8 ).

[0099] Figure 8 The blocks in the drawings represent operations and / or parts thereof, and the lines connecting the various blocks do not imply any particular order or dependency of the operations or parts thereof. Figure 8 The disclosure of the steps of the method 250 described herein should not be construed as necessarily determining the order in which the steps will be performed. On the contrary, although an illustrative order is indicated, it should be understood that the order of the steps can be modified when appropriate. Therefore, certain operations can be performed in a different order or simultaneously.

[0100] like Figure 8 As shown, the method 250 includes the step of initiating 252 a pivot turn maneuver 30 of the aircraft 10. The aircraft 10 has a pivot turn load alleviation (PTLA) braking system 12 (see Figure 1A to Figure 1B , Figure 2A As described in detail above, the PTLA brake system 12 includes a brake control system 14 (see Figure 1A to Figure 1B , Figure 2A ), the brake control system 14 is operatively coupled to at least two main landing gears 24 (see Figure 1A to Figure 1B , Figure 2A Each of the at least two main landing gears 24 has two or more wheels 46 (see Figure 1A to Figure 1B , Figure 2A ). For example, each main landing gear 24 may have two wheels, four wheels, six wheels, or another suitable number of wheels. The brake control system 14 controls the braking of at least two main landing gears 24. The PTLA brake system 12 also includes a pivoting turn load mitigation (PTLA) brake inhibition subsystem 16 (see FIG. 1 ) coupled to the brake control system 14. Figure 1A to Figure 1B , Figure 2A ).

[0101] Start 252 (see Figure 8 The steps of performing a pivot turn maneuver 30 of the aircraft 10 may also include initiating 252 a pivot turn maneuver 30 of the aircraft 10 having the PTLA braking system 12, wherein the braking control system 14 includes a plurality of braking control units 74 (see Figure 2A ) and multiple brake control valves 82 (see Figure 2A ), wherein one of the plurality of brake control units 74 receives a PTLA brake inhibition command 90 from the PTLA brake inhibition subsystem 16 (see Figure 2A ) to inhibit the generation of at least one braking command 76 (see Figure 2A ).

[0102] like Figure 8 As shown, the method 250 also includes once one or more brake inhibit conditions 94 (see Figure 2A ), to one or more brake control units 74 (see Figure 2A ) initiates 254 the pivoting load alleviation (PTLA) brake inhibit command 90 of the PTLA brake inhibit subsystem 16 (see Figure 2A ) steps. Start 254 (see Figure 8 ) also includes initiating the PTLA brake inhibit command 90 upon satisfaction of one or more brake inhibit conditions 94 including one or more of the following: (a) when the aircraft 10 is in an on-ground position 98 (see Figure 2A ), the aircraft ground indicator 96 (see Figure 2A ); (b) when the aircraft 10 has an aircraft ground speed of 101 (see Figure 2A ) is less than the pivoting load easing (PTLA) speed threshold 104 (see Figure 2A), the acceptable aircraft ground speed is 100 (see Figure 2A ); or (c) by the monitoring logic 108 of the PTLA brake inhibition subsystem 16 (see Figure 2A ) generated by the pivoting load alleviation (PTLA) active flag command indication 106 (see Figure 2A ) to monitor the brake pedal position 110 (see Figure 2A ) to adjust the brake pedal curve 112 according to the plurality of pivot turns (see Figure 2A , Figures 4 to 7 ) to detect the pivoting maneuver 30 (see Figure 2A )31 (see Figure 2A ).

[0103] like Figure 8 As shown, the method 250 also includes inhibiting the pivoting of two or more wheels 46 (see FIG. 1 ) of the main landing gear 32 during the pivoting turn maneuver 30. Figure 1A to Figure 1B , Figure 2A ) in the step of braking one or more wheels 256, so that at least one wheel 46 of the two or more wheels 46 is in an unbraked state 52 (see Figure 2A ), and the remaining number 54 of the two or more wheels 46 (see Figure 2A ) is in braking state 56 (see Figure 2A The PTLA braking system 12 mitigates structural loads 28a on the pivoting main landing gear 32 of the aircraft 10 during the pivoting turn maneuver 30 and reduces wear 136 on at least one wheel 46 in the unbraked state 52 (see Figure 2A ).

[0104] Steps for inhibiting brake 256 (see Figure 8 ) may also include inhibiting braking 256 of one of the wheels 46, two wheels 46, or three wheels 46 during the pivoting turning maneuver 30 of the aircraft 10. The step of inhibiting braking 256 may also include inhibiting the inhibited wheel selection 50 (see Figure 2A ) brake 256, for example, an axle pair 48a of wheel 46 (see Figure 2A ), and in the subsequent pivoting maneuver 30a (see Figure 2A ), one or more but not all wheels 46 of the inhibited wheel selection 50, for example, an axle pair 48a of the wheel 46, are selected in a sequential order 51 (see Figure 2A ) to a different one or more but not all wheels 46, such as a different axle pair 48b of wheels 46 (see Figure 2A ).

[0105] like Figure 8As shown, after the step of inhibiting braking 256, the method 250 may also optionally include once one or more brake inhibition deactivation conditions 118 (see Figure 2A ), then deactivate the PTLA brake inhibit command 90 at step 258. As described above, the one or more brake inhibit deactivation conditions 118 include one or more of the following: (a) the aircraft ground speed 101 of the aircraft 10 (see Figure 2A ) exceeds the pivoting load easing (PTLA) speed threshold 104 (see Figure 2A ); or (b) left brake pedal command 120a (see Figure 2A ) and right brake pedal command 120b (see Figure 2A ) exceed the pivoting load easing (PTLA) triggering brake pedal command threshold 122 (see Figure 2A ) for at least a predetermined period of time 124 (see Figure 2A ); or (c) the aircraft 10 enters the active parking brake state 126 (see Figure 2A ).

[0106] like Figure 8 As shown, the method 250 may also optionally include, when the aircraft 10 has a taxi brake release function 130 (see Figure 2A ) and integrating 260 the PTLA brake inhibit subsystem 16 with the taxi brake release function 130 already present and existing in the aircraft 10 so that the taxi brake release function 130 is a PTLA brake inhibit command 90 (see Figure 2A , FIG. 3A to FIG. 3C )Selection round selection 50 (see FIG. 3A to FIG. 3C ) to inhibit braking of one or more but not all wheels 46 of the pivoting main landing gear 32.

[0107] Reference now Fig. 9 and Fig.10 , Fig. 9 is a flow chart of an embodiment of an aircraft manufacturing and service method 300. Fig.10 is an illustration of a functional block diagram of an embodiment of aircraft 316. Figures 9 and 10 , the version of this disclosure can be found in Fig. 9 Aircraft manufacturing and service method 300 is shown and described below. Fig.10 The aircraft 316 is shown in the context of the following. During pre-production, exemplary aircraft manufacturing and service method 300 (see FIG. Fig. 9 ) may include aircraft 316 (see Fig.10 ) specifications and design 302 (see Fig. 9 ) and material procurement 304 (see Fig. 9 During manufacture, the aircraft 316 (see Fig.10) components and subassemblies manufacturing 306 (see Fig. 9 ) and system integration 308 (see Fig. 9 Thereafter, the aircraft 316 (see Fig.10 ) can undergo certification and delivery 310 (see Fig. 9 ) for commissioning 312 (see Fig. 9 ). When served by a client 312 (see Fig. 9 ), aircraft 316 (see Fig.10 ) can be arranged for routine maintenance and repairs 314 (see Fig. 9 ), the routine maintenance and repair 314 may also include modification, reconstruction, refurbishment and other appropriate repairs.

[0108] Aircraft manufacturing and maintenance method 300 (see Fig. 9 ) may be performed or executed by a system integrator, a third party, and / or an operator (e.g., a customer). For purposes of this specification, a system integrator may include, but is not limited to, any number of aircraft manufacturers and primary system subcontractors; a third party may include, but is not limited to, any number of suppliers, subcontractors, and vendors; and an operator may include airlines, leasing companies, military entities, maintenance organizations, and other suitable operators.

[0109] like Fig.10 As shown, aircraft 316 produced by exemplary aircraft manufacturing and service method 300 may include airframe 318 having plurality of systems 320 and interior 322. Fig.10 As further shown, an embodiment of system 320 may include one or more of propulsion system 324, electrical system 326, hydraulic system 328, and environmental system 330. Any number of other systems may be included. Although an aerospace embodiment is shown, the principles of the present disclosure may be applied to other industries, such as the automotive industry including motor vehicles, the marine industry including boats, ships, and submarines, and other suitable industries.

[0110] Methods and systems embodied herein may be used in aircraft manufacturing and service method 300 (see Fig. 9 ) during any one or more stages of the process. For example, corresponding to component and subassembly manufacturing 306 (see Fig. 9 ) can be used in a manner similar to that of aircraft 316 (see Fig.10 ) Service 312 (see Fig. 9 ) is manufactured or processed in a manner that produces components or subassemblies. Furthermore, in the manufacture of components and subassemblies 306 (see Fig. 9 ) and system integration 308 (see Fig. 9 ) period, for example by sufficiently accelerating the aircraft 316 (see Fig.10) assembly or reduce its cost, one or more method embodiments, system embodiments, or a combination thereof may be utilized. Similarly, when the aircraft 316 (see Fig.10 ) in service 312 (see Fig. 9 ), for example but not limited to, maintenance and repair 314 can be performed using one or more of the method version, system version, or a combination thereof (see Fig. 9 ).

[0111] The disclosed PTLA braking system 12 (see Figure 1A to Figure 1B , Figure 2A ) and Method 250 (see Figure 8 ) version slows down the pivot turn maneuver 30 of the aircraft 10 (see Figure 2A ) and the pivoting main landing gear 32 of the aircraft 10 (see Figure 2A ) such as structural loads 28a (see Figure 2A ) and torsional load reaction force 28b (see Figure 2A ) load 28 (see Figure 2A ) or torque loads, and reduces wear 136 on one or more wheels 46 of the pivoting main landing gear 32 having brakes 58 inhibited by the PTLA braking system 12, and reduces wear 136 on the tires of the wheels 46. In addition, the PTLA braking system 12 inhibits braking on one or more brakes 58 on the pivoting main landing gear 32 to reduce the torsional load reaction force 28b (see Figure 2A ). Pivoting main landing gear 32 (see Figure 2A ) such as structural loads 28a (see Figure 2A ) and torsional load reaction force 28b (see Figure 2A ) load 28 (see Figure 2A ) or torque load reduction because only a portion of the brake 58, such as half of the brake 58, is applied, while the other portion of the brake 58 or the other half of the brake 58 is inhibited or unbraked. The PTLA brake system 12 provides load relief for a 2-point turn maneuver or a pivot turn maneuver 30.

[0112] In addition, the disclosed PTLA brake system 12 (see Figure 1A to Figure 1B , Figure 2A ) and Method 250 (see Figure 8 ) version can also reduce the steering force 134 (see Figure 2A ), which in turn reduces wear 136. When the inner wheel 46e (see Figure 2A ) is released, the PTLA braking system 12 can also provide U-turn optimization 138 (see Figure 2AAn additional advantage of the PTLA braking system 12 is that the overall weight of the main landing gear 24 can also be reduced because, with reduced structural loads 28a and reduced steering forces 134, various components and materials on the main landing gear 24 can be reduced or eliminated, such as a smaller, reduced weight scissor link, a smaller, reduced weight torque link, or another small size structure, such as a pivoting main landing gear 32, on the main landing gear 24. In addition, the PTLA braking system 12 can be reduced by having a 2-main landing gear configuration 36 (see Figure 1A ) of the aircraft 10 to reduce the braking load during a brake pivot maneuver or pivot turn maneuver 30 to utilize individual wheel brake control.

[0113] In addition, the disclosed PTLA brake system 12 (see Figure 1A to Figure 1B , Figure 2A ) and the version of Method 250 (see Figure 8 ) provides a similar function to the taxi brake release function 130 that may already exist or be present on the aircraft 10 (see Figure 2A ) to obtain the integrated taxi brake release function 132 (see Figure 2A ). The taxi brake release function 130 is performed during wheel selection 50 (see FIG. 3A to FIG. 3C ) when selecting a predetermined one or more but not all wheels 46, such as a pair of wheels 46, and the PTLA brake inhibition command 90 uses the wheel selection 50 to assist the brake control unit 74 to inhibit braking of one or more but not all wheels 46 of the pivoting main landing gear 32, such as the pair 48 of wheels 46.

[0114] In addition, the PTLA brake system 12 (see Figure 1A to Figure 1B , Figure 2A ) and Method 250 (see Figure 8 ) provides a pair of axles 48a of wheels 46 which are side by side and share a common axle 49 between them (see Figure 2A ). A paired axle release method with two wheels 46 sharing axle 49 on a four wheel 46 two axle 49 main landing gear 24 is an exemplary scheme or arrangement where half of the wheels 46 are unbraked and restrained by the PTLA brake system 12 and the other half of the wheels 46 are braked during the pivoting turning maneuver 30. The PTLA brake system 12 logic can alternate between restraining the pair 48 of front wheels 46c and restraining the pair 48 of rear wheels 46d on the pivoting main landing gear 32 (see Figure 2A It should be noted that the PTLA braking system 12 may also inhibit braking of one wheel 46 , two wheels 46 , three wheels 46 , or another suitable number of wheels 46 during a pivot turn maneuver 30 performed by the aircraft 10 .

[0115] Furthermore, the present disclosure includes embodiments according to the following clauses:

[0116] Clause 1. An aircraft, comprising:

[0117] body;

[0118] one or more wings attached to the fuselage;

[0119] a plurality of landing gears attached to the fuselage, the plurality of landing gears comprising a nose landing gear and at least two main landing gears, each of the at least two main landing gears having two or more wheels, wherein during a pivoting turning maneuver of the aircraft, one of the at least two main landing gears comprises a pivoting main landing gear; and

[0120] A pivot turn load alleviating (PTLA) braking system, the pivot turn load alleviating (PTLA) braking system comprising:

[0121] a brake control system operably coupled to the at least two main landing gears, wherein the brake control system controls braking of the at least two main landing gears; and

[0122] a pivot turn load alleviating (PTLA) brake inhibiting subsystem coupled to the brake control system, wherein the PTLA brake inhibiting subsystem inhibits braking of one or more of the two or more wheels comprising one main landing gear of the pivoting main landing gear during the pivot turn maneuver such that at least one of the two or more wheels is in an unbraked state and a remaining number of the two or more wheels is in a braked state,

[0123] Wherein, the PTLA braking system mitigates structural loads on the pivoting main landing gear during pivoting turning maneuvers of the aircraft and reduces wear on the at least one wheel in the unbraked state.

[0124] Clause 2. The PTLA braking system 12 of Clause 1, wherein the at least two main landing gears 24 include a left main landing gear 24a and a right main landing gear 24b, each main landing gear having two pairs 48 of wheels 46, each pair 48 of wheels 46 being disposed on an axle 49.

[0125] Clause 3. The PTLA braking system 12 of Clause 1, wherein the at least two main landing gears 24 include one of a 2-main landing gear configuration 36 , a 3-main landing gear configuration 38 , or a 4-main landing gear configuration 40 .

[0126] Clause 4. The aircraft of clause 3, wherein the PTLA brake inhibit command is deactivated upon satisfaction of one or more brake inhibit deactivation conditions, the one or more brake inhibit deactivation conditions comprising one or more of the following:

[0127] (a) the aircraft ground speed of the aircraft exceeds the pivot turn load alleviation (PTLA) speed threshold;

[0128] (b) both the left brake pedal command and the right brake pedal command exceed the pivot turning load alleviation (PTLA) triggering brake pedal command threshold for at least a predetermined period of time; or

[0129] (c) The aircraft enters an active parking brake state.

[0130] With the benefit of the teachings presented in the foregoing description and the associated drawings, those skilled in the art will appreciate many modifications and other embodiments of the present disclosure. The embodiments described herein are intended to be illustrative and are not intended to be restrictive or exhaustive. Although specific terms are employed herein, they are used only in a general and descriptive sense, not for the purpose of limitation. Any claimed embodiment of the present disclosure does not necessarily include all embodiments of the present disclosure.

Claims

1. A pivoting turn load mitigation or PTLA braking system (12), the PTLA braking system (12) being used to mitigate structural loads (28a) on a pivoting main landing gear (32) of an aircraft (10) during a pivoting turn maneuver (30), the PTLA braking system (12) comprising: A brake control system (14) operatively coupled to at least two main landing gears (24), each of the at least two main landing gears (24) having two or more wheels (46), wherein the brake control system (14) controls braking of the at least two main landing gears (24); a pivot turn load mitigation or PTLA brake inhibit subsystem (16), the PTLA brake inhibit subsystem (16) being coupled to the brake control system (14), wherein the PTLA brake inhibit subsystem (16) inhibits braking of one or more of the two or more wheels (46) of one main landing gear (24) including the pivoting main landing gear (32) during the pivot turn maneuver (30) such that at least one of the two or more wheels (46) is in an unbraked state (52) and a remaining number (54) of the two or more wheels (46) are in a braked state (56), and wherein the PTLA brake inhibit subsystem (16) uses aircraft data and thresholds to determine which brakes to apply and which brakes to inhibit; and a taxi brake release function (130), and the PTLA brake inhibit subsystem (16) is integrated with the taxi brake release function (130) so that the taxi brake release function (130) selects the wheel select (50) for the PTLA brake inhibit command (90) to inhibit braking of one or more but not all of the wheels (46) of the pivoting main landing gear (32), The PTLA braking system (12) mitigates the structural loads (28a) on the pivoting main landing gear (32) of the aircraft (10) during the pivoting turning maneuver (30) and reduces wear (136) on the at least one wheel (46) in the unbraked state (52).

2. The PTLA braking system (12) according to claim 1, wherein: The at least two main landing gears (24) include a left main landing gear (24a) and a right main landing gear (24b), each main landing gear having two pairs (48) of wheels (46), each pair (48) of wheels (46) being arranged on an axle (49).

3. The PTLA braking system (12) according to claim 1 or 2, wherein: The at least two main landing gears (24) include one of a 2-main landing gear configuration (36), a 3-main landing gear configuration (38), or a 4-main landing gear configuration (40).

4. The PTLA braking system (12) according to claim 1 or 2, wherein: The pivoting main landing gear (32) has four wheels (46), and the PTLA brake inhibition subsystem (16) inhibits braking of one of one wheel (46), two wheels (46), or three wheels (46) during the pivoting turning maneuver (30) of the aircraft (10).

5. The PTLA braking system (12) according to claim 1, wherein: Once one or more brake inhibit conditions (94) are met, the PTLA brake inhibit subsystem (16) inhibits braking via initiating (92) a pivoting load mitigation, or PTLA brake inhibit command (90), to one or more brake control units (74) of the brake control system (14).

6. The PTLA braking system (12) according to claim 5, wherein: The one or more brake inhibiting conditions (94) include one or more of the following: (a) the on-ground state of the aircraft (96) when the aircraft (10) is in the on-ground position (98); (b) an acceptable aircraft ground speed (100) when the aircraft ground speed (101) of the aircraft (10) is less than the pivot turn load alleviation or PTLA speed threshold (104); or (c) a pivot turn load mitigation, i.e., a PTLA active flag command indication (106), generated by monitoring logic (108) of the PTLA brake inhibition subsystem (16) to monitor brake pedal position (110) to detect the start (31) of the pivot turn maneuver (30) based on one of a plurality of pivot turn brake pedal profiles (112).

7. The PTLA braking system (12) according to claim 5 or 6, wherein: The PTLA brake inhibit command (90) is deactivated upon satisfaction of one or more brake inhibit deactivation conditions (118), the one or more brake inhibit deactivation conditions including one or more of the following: (a) the aircraft ground speed (101) of the aircraft (10) exceeds the pivot turn load alleviation or PTLA speed threshold (104); (b) both the left brake pedal command (120a) and the right brake pedal command (120b) exceed the pivoting turn load mitigation, PTLA triggering brake pedal command threshold (122) for at least a predetermined period of time (124); or (c) The aircraft (10) enters an active parking brake state (126).

8. The PTLA braking system (12) according to claim 5 or 6, wherein: Once one or more of the brake inhibit conditions (94) are satisfied, the PTLA brake inhibit command (90) is initiated to inhibit braking of the wheel selection (50) of one axle pair (48a) of wheels (46) on the pivoting main landing gear (32), and upon initiation (31) of a subsequent pivoting turn maneuver (30a), the wheel selection (50) of the one axle pair (48a) of wheels (46) is changed to a different axle pair (48b) of wheels (46) in a sequential order (51).

9. A method (250) for mitigating structural loads (28a) on a pivoting main landing gear (32) of an aircraft (10) during a pivoting turn maneuver (30), the method (250) comprising the following steps: (252) Initiating the pivot turn maneuver (30) using the aircraft (10), the aircraft (10) having a pivot turn load alleviation or PTLA braking system (12), the PTLA braking system (12) comprising: A brake control system (14) operatively coupled to at least two main landing gears (24), each of the at least two main landing gears (24) having two or more wheels (46), wherein the brake control system (14) controls braking of the at least two main landing gears (24); a pivot turn load mitigation or PTLA brake inhibit subsystem (16) coupled to the brake control system (14), wherein the PTLA brake inhibit subsystem (16) uses aircraft data and thresholds to determine which brakes to apply and which brakes to inhibit; and a taxi brake release function (130), and the PTLA brake inhibit subsystem (16) is integrated with the taxi brake release function (130) so that the taxi brake release function (130) selects a wheel select (50) for the PTLA brake inhibit command (90) to inhibit braking of one or more but not all of the wheels (46) of the pivoting main landing gear (32); (254) initiating a pivoting turn load mitigation, i.e., a PTLA brake inhibit command (90) of the PTLA brake inhibit subsystem (16) to one or more brake control units (74) of the brake control system (14) upon satisfaction of one or more brake inhibit conditions (94); and (256) during the pivoting turn maneuver (30), inhibiting braking of one or more of the two or more wheels (46) of the pivoting main landing gear (32) such that at least one wheel (46) of the two or more wheels (46) is in an unbraked state (52) and a remaining number (54) of the two or more wheels (46) are in a braked state (56), The PTLA braking system (12) mitigates the structural loads (28a) on the pivoting main landing gear (32) of the aircraft (10) during the pivoting turning maneuver (30) and reduces wear (136) on the at least one wheel (46) in the unbraked state (52).

10. The method (250) of claim 9, wherein: Initiating (254) the PTLA brake inhibit command (90) of the PTLA brake inhibit subsystem (16) further includes initiating the PTLA brake inhibit command (90) of the PTLA brake inhibit subsystem (16) upon one or more of the brake inhibit conditions (94) being satisfied, the brake inhibit conditions (94) including one or more of the following: (a) the on-ground state of the aircraft (96) when the aircraft (10) is in the on-ground position (98); (b) an acceptable aircraft ground speed (100) when the aircraft ground speed (101) of the aircraft (10) is less than the pivot turn load alleviation or PTLA speed threshold (104); or (c) a pivot turn load mitigation, i.e., a PTLA active flag command indication (106), generated by monitoring logic (108) of the PTLA brake inhibition subsystem (16) to monitor brake pedal position (110) to detect the start (31) of the pivot turn maneuver (30) based on one of a plurality of pivot turn brake pedal profiles (112).

11. The method (250) according to claim 9 or 10, further comprising: After inhibiting braking (256), the PTLA brake inhibit command (90) is deactivated (258) upon satisfaction of one or more brake inhibit deactivation conditions (118), the one or more brake inhibit deactivation conditions (118) comprising one or more of the following: (a) the aircraft ground speed (101) of the aircraft (10) exceeds the pivot turn load alleviation or PTLA speed threshold (104); (b) both the left brake pedal command (120a) and the right brake pedal command (120b) exceed the pivoting turn load mitigation, PTLA triggering brake pedal command threshold (122) for at least a predetermined period of time (124); or (c) The aircraft (10) enters an active parking brake state (126).

12. The method (250) according to claim 9 or 10, wherein: Inhibiting braking (256) also includes inhibiting braking (256) of one of one wheel (46), two wheels (46), or three wheels (46) during the pivoting turn maneuver (30) of the aircraft (10).

13. The method (250) according to claim 9 or 10, wherein: Inhibiting braking (256) also includes inhibiting braking (256) of wheel selection (50) of one axle pair (48a) of wheels (46) on the pivoting main landing gear (32), and in the event of starting (31) a subsequent pivoting turning maneuver (30a), the inhibited wheel selection (50) of the one axle pair (48a) of wheels (46) is changed to a different axle pair (48b) of wheels (46) in a sequential order (51).

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