Abstract: An aircraft brake system includes a supply line for supplying hydraulic fluid to wheel brakes, and an associated return line. Hydraulic fluid is replenished in at least a portion of the return line both before applying a braking force to the one or more wheels of the aircraft during landing, and before an intervening, optional, step if so performed of testing the brake system before landing of the aircraft. Replenishing the hydraulic fluid can be conducted by a control unit automatically and/or in response to a pressure drop in the return line measure by a transducer.

Abstract: A hydraulic brake system for activating the wheel brakes of an aircraft landing gear assembly includes a hydraulic fluid supply line and an associated return line. There is a valve which separates a source of hydraulic fluid from a portion of the return line and an associated leak path associated with the valve that in use maintains the pressure and/or volume of hydraulic fluid in the portion of the return line above a minimum acceptable level. The leak path may be provided by a hole drilled in a part (e.g. the poppet) of a non-return check valve.

Abstract: An aircraft brake control system for controlling antiskid braking of an aircraft wheel is disclosed including a control assembly having a mode controller which sets the mode of operation of an antiskid brake calculator, configured to set a first mode, when an input of the indication of a brake energy supply configuration indicates a first brake energy supply being used, in which the antiskid brake calculator applies a first restriction level on a rise rate of the antiskid brake command, and a second mode, when the input 305 indicates a second brake energy supply being used, in which the antiskid brake calculator applies a second, lower, restriction level on a rise rate of the antiskid brake command.

Abstract: An aircraft is disclosed including a ground manoeuvre control unit for automatically controlling ground manoeuvres. The aircraft has control mechanisms such as a rudder, nose wheel steering, spoilers, wheel brakes and the like for controlling motion of the aircraft. The control unit is configured to receive lateral input demands concerning lateral motion of the aircraft (e.g. heading control) and longitudinal input demands concerning longitudinal motion of the aircraft (e.g. deceleration). The control unit passes on the input demands as output demands to the relevant control mechanisms of the aircraft with, if so required, a modification which prioritises one of the lateral input demand and longitudinal input demand based on the risk of a lateral runway excursion and the risk of a longitudinal runway excursion.

Abstract: An aircraft brake control system for controlling antiskid braking of an aircraft wheel is disclosed including a control assembly having a mode controller which sets the mode of operation of an antiskid brake calculator, configured to set a first mode, when an input of the indication of a brake energy supply configuration indicates a first brake energy supply being used, in which the antiskid brake calculator applies a first restriction level on a rise rate of the antiskid brake command, and a second mode, when the input 305 indicates a second brake energy supply being used, in which the antiskid brake calculator applies a second, lower, restriction level on a rise rate of the antiskid brake command.

Abstract: A method of removing hydraulic fluid from an aircraft hydraulic system is disclosed including a hydraulically actuated mechanism that is actuated by an electrohydraulic servo valve, a hydraulic fluid port through which hydraulic fluid can escape, and a hydraulic fuse with a closed state and an open state between the electrohydraulic servo valve and the hydraulic fluid port. The hydraulic fluid port is opened, and then the activation of the electrohydraulic servo valve is controlled to force hydraulic fluid to escape from the hydraulic system via the hydraulic fluid port, the control being so that the hydraulic fuse does not enter and remain in the closed state.

Abstract: A speed determination system for an aircraft including one or more interfaces arranged to receive first speed data from a first speed measurement system and second speed data from a second speed measurement system. The first speed measurement system provides the first speed data using global positioning system data. The second speed measurement system provides the second speed data based on a second speed measurement. The speed determination system includes a processor arranged to determine whether the data received from the first speed measurement system is reliable. If global positioning data is determined to be reliable, the speed determination system determines a speed from the first speed data and determines correction values for the second speed measurement system. If global positioning data is determined to be unreliable, the speed determination system determines a speed from the second speed data and the correction values.

Abstract: A method of parking an aircraft is disclosed including flight crew pedal braking to cause a brake force to be applied to the aircraft wheel brakes to slow the aircraft to a stationary state in which it is ready to be parked. Flight crew then activate a parking brake device and then release the pedal braking. An electronic control device, forming part of the aircraft’s braking system for example, automatically intervenes, following the manual release of the pedal braking, to cause a brake force to continue to be applied to the wheels. This may be until sufficient brake force is applied, as a result of the activation of the parking brake device, to hold the aircraft in its parked state or may be for a predetermined period of time, say, ten seconds.

Abstract: A method of removing hydraulic fluid from an aircraft hydraulic system is disclosed including a hydraulically actuated mechanism that is actuated by an electrohydraulic servo valve, a hydraulic fluid port through which hydraulic fluid can escape, and a hydraulic fuse with a closed state and an open state between the electrohydraulic servo valve and the hydraulic fluid port. The hydraulic fluid port is opened, and then the activation of the electrohydraulic servo valve is controlled to force hydraulic fluid to escape from the hydraulic system via the hydraulic fluid port, the control being so that the hydraulic fuse does not enter and remain in the closed state.

Abstract: A monitoring system for a speed determination system in an aircraft is disclosed. A method, which may be implemented by a computer program, of monitoring a speed determination system for an aircraft is also disclosed. The speed determination system includes a first speed measurement system and a second speed measurement system and the second speed measurement system is associated with a predetermined behaviour characteristic. The monitoring system includes a processor arranged to receive speed data provided by the speed determination system and to perform a correspondence determination process comprising processing the received speed data to determine whether a correspondence condition is satisfied, the correspondence condition having a correspondence between the received speed data and the predetermined behaviour characteristic of the second speed measurement system.

Abstract: An aircraft system for an aircraft is disclosed having a controller that is configured to receive at least one signal during a landing procedure of the aircraft and to determine that the aircraft is at a predetermined stage in the landing procedure, on the basis of the at least one signal. The predetermined stage in the landing procedure is before a command to extend at least one landing gear of the aircraft is issued during the landing procedure. The controller is configured to cause initiation of at least a part of a procedure to interrogate an aircraft braking system, on the basis of the determination.

Abstract: A brake control system for an aircraft is disclosed having a plurality of brake actuators. Each brake actuator includes a braked state imparting an unknown braking torque, and a parked state imparting a known braking torque. The system includes a controller to control the states of the brake actuators. In response to a parking signal, when at least one of the brake actuators is in the braked or parked state, the controller performs a parking procedure comprising maintaining a first brake actuator in the braked or parked state whilst changing the state of a second brake actuator from the braked state to the parked state. Also disclosed is an aircraft including the brake control system, a method of controlling a brake system for an aircraft, and a non-transitory computer readable storage medium.

Abstract: An aircraft system having a first set of components for performing a function of the aircraft system, and a second, alternative, set of components for performing the function of the aircraft system. The aircraft system has and a controller configured to receive scenario data indicative of a scenario during which the function of the aircraft system is to be performed, and, where each of the first and second sets of components are operational, the controller is configured to select between the first or the second set of components to perform the aircraft system function during the scenario based on the received scenario data. The controller is configured to control the selected set of components to perform the function during the scenario.

Abstract: An actuator is disclosed including an actuator body mounted for movement over a range of motion, the range of motion including a first part and a second part, the first part being the range of motion extending between an end position and the second part. The actuator includes a motor coupled to the actuator body to move the actuator body in the first direction and a controller configured to control the supply of current to drive the motor. The mechanical resistance to movement of the actuator body in the first direction is higher in the first part of the range of motion than in the second part of the range of motion. The controller is configured such that any additional current supplied to the motor when the actuator body is in the first part of the range of motion is limited thereby causing the speed of the actuator body to reduce as the actuator body approaches the end position.

Abstract: A brake control system 200 and method 300 for controlling a park brake of an aircraft including a controller 201 configured to cause an increase in a brake torque of the park brake based of an indication to the controller. The indication is generated in response to touchdown of the aircraft.

Abstract: An aircraft brake control system for controlling antiskid braking of an aircraft wheel is disclosed including a control assembly having a mode controller which sets the mode of operation of an antiskid brake calculator, configured to set a first mode, when an input of the indication of a brake energy supply configuration indicates a first brake energy supply being used, in which the antiskid brake calculator applies a first restriction level on a rise rate of the antiskid brake command, and a second mode, when the input 305 indicates a second brake energy supply being used, in which the antiskid brake calculator applies a second, lower, restriction level on a rise rate of the antiskid brake command.

Abstract: An aircraft brake control system for controlling anti-skid braking of at least first and second wheels in a wheel set of an aircraft is disclosed. The system includes a control assembly having wheel speed inputs including an input of an indication of the wheel speed of the first wheel, and an input of an indication of the wheel speed of the second wheel, a wheel speed comparator for determining which of the wheel speeds indicated is a lowest wheel speed, and an output for indicating a wheel speed other than the lowest wheel speed. An aircraft landing gear, an aircraft, and methods of braking an aircraft are also disclosed.

Abstract: A tachometer system for an aircraft landing gear. The tachometer system includes a tachometer arranged to generate a variable voltage signal in response to the rotation of a wheel of the aircraft landing gear, and a processing system arranged to output a speed signal indicative of the rotation speed of the wheel of the aircraft landing gear. The speed signal is determined from the variable voltage signal from the tachometer using a set of determined parameters. The determined parameters of the processing system are determined from the voltage levels of the variable voltage signal.

Abstract: A tachometer system for an aircraft landing gear. The tachometer system includes a tachometer arranged to generate a variable voltage signal in response to the rotation of a wheel of the aircraft landing gear, and a processing system arranged to output a speed signal indicative of the rotation speed of the wheel of the aircraft landing gear. The speed signal is determined from the variable voltage signal from the tachometer using a set of determined parameters. The determined parameters of the processing system are determined from the voltage levels of the variable voltage signal.