Abstract: A method of determining whether a landing event of an aircraft is hard may comprise: receiving, by a controller via a stroke position sensor, a stroke profile as a function of time for a shock strut; receiving, by the controller via a gas pressure sensor, a gas pressure in a gas chamber of the shock strut; receiving, by the controller via a wheel speed sensor, a wheel speed of a tire in a landing gear assembly; calculating, by the controller, multiple time dependent functions based on the stroke profile of the shock strut, based on the gas pressure, a shock strut temperature, and the wheel speed; and comparing, by the controller, the multiple time dependent functions to respective predetermined thresholds to determine whether the landing event is hard.

Abstract: A method for monitoring a shock strut may comprise measuring a first shock strut pressure, measuring an ambient temperature, measuring a shock strut stroke, measuring a second shock strut pressure, and determining a servicing condition of the shock strut based upon the first shock strut pressure, the ambient temperature, the shock strut stroke, and the second shock strut pressure, wherein the servicing condition indicates whether it is desirable for the shock strut to be serviced with at least one of a liquid and a gas. The first shock strut pressure and the shock strut stroke may be measured before the takeoff event with a weight of an aircraft supported by the shock strut.

Abstract: A shock strut servicing assistance system may comprise a controller including a display, and a tangible, non-transitory memory configured to communicate with the controller. The tangible, non-transitory memory may have instructions stored thereon that, in response to execution by the controller, cause the controller to perform operations comprising calculating, by the controller, a first fluid level, generating, by the controller, a first datum corresponding to the first fluid level, receiving, by the shock strut, a fluid in response to the first datum, calculating, by the controller, a second fluid level, generating, by the controller, a second datum, and storing, by the controller, a final fluid level.

Abstract: A method for monitoring a shock strut may comprise measuring a first shock strut pressure, measuring an ambient temperature, measuring a shock strut stroke, measuring a second shock strut pressure, and determining a servicing condition of the shock strut based upon the first shock strut pressure, the ambient temperature, the shock strut stroke, and the second shock strut pressure, wherein the servicing condition indicates whether it is desirable for the shock strut to be serviced with at least one of a liquid and a gas. The first shock strut pressure and the shock strut stroke may be measured before the takeoff event with a weight of an aircraft supported by the shock strut.

Abstract: A method for monitoring a shock strut may comprise measuring a first shock strut pressure, measuring an ambient temperature, measuring a shock strut stroke, measuring a second shock strut pressure, and determining a servicing condition of the shock strut based upon the first shock strut pressure, the ambient temperature, the shock strut stroke, and the second shock strut pressure, wherein the servicing condition indicates whether it is desirable for the shock strut to be serviced with at least one of a liquid and a gas. The first shock strut pressure and the shock strut stroke may be measured before the takeoff event with a weight of an aircraft supported by the shock strut.

Abstract: An uplock system includes a cam plate comprising a cam channel, a hook configured to rotate with respect to the cam plate, a follower rotatably coupled to the hook, wherein a portion of the follower moves within the cam channel in response to rotation of the hook, a stopper configured to engage the follower, and a first biasing member configured to bias the stopper towards the follower to stop the follower from moving within the cam channel, thereby locking the hook in a locked position.

Abstract: A system for controlling landing gear subsystems may comprise a controller and a first motor drive unit in operable communication with the controller. A first electric motor and a second electric motor may be in operable communication with the first motor drive unit. A second motor drive unit may be in operable communication with the controller. A third electric motor and a fourth electric motor may be in operable communication with the second motor drive unit. An AC/DC converter may be electrically coupled to the first drive unit and the second motor drive unit.

Abstract: A method for monitoring a dual-stage shock strut may include measuring a first primary chamber pressure when the dual-stage shock strut is in a first state, measuring a first secondary chamber pressure when the dual-stage shock strut is in the first state, measuring a shock strut stroke when the dual-stage shock strut is in the first state, measuring a first temperature, measuring a second temperature, measuring a second primary chamber pressure when the dual-stage shock strut is in a second state, measuring a second secondary chamber pressure when the dual-stage shock strut is in the second state, and determining a servicing condition of the shock strut based upon at least the first primary chamber pressure, the first secondary chamber pressure, the shock strut stroke, the first temperature, the second temperature, the second primary chamber pressure, and the second secondary chamber pressure.

Abstract: A method of determining whether a landing event of an aircraft is hard may comprise: receiving, by a controller via a stroke position sensor, a stroke profile as a function of time for a shock strut; receiving, by the controller via a gas pressure sensor, a gas pressure in a gas chamber of the shock strut; receiving, by the controller via a wheel speed sensor, a wheel speed of a tire in a landing gear assembly; calculating, by the controller, multiple time dependent functions based on the stroke profile of the shock strut, based on the gas pressure, a shock strut temperature, and the wheel speed; and comparing, by the controller, the multiple time dependent functions to respective predetermined thresholds to determine whether the landing event is hard.

Abstract: A method for monitoring a dual-stage, stroke activated, mixed fluid gas shock strut includes receiving, by a controller, primary chamber temperature and pressure sensor readings, secondary chamber pressure and temperature sensor readings, and a shock strut stroke sensor reading, calculating, by the controller, a compression factor, determining, by the controller, a plurality of compression factors for known oil volumes based on the primary chamber temperature sensor reading and/or the shock strut stroke sensor reading, and calculating, by the controller, an oil volume in a primary chamber of the shock strut, a number of moles of gas in the primary chamber of the shock strut, a volume of gas in a secondary chamber of the shock strut, and a number of moles of gas in the secondary chamber.

Abstract: A method for monitoring a dual-stage, separated gas/fluid shock strut includes receiving, by a controller, a primary chamber temperature sensor reading, a primary chamber pressure sensor reading, and a shock strut stroke sensor reading, calculating, by the controller, a secondary chamber nominal pressure based upon the primary chamber temperature sensor reading, determining, by the controller, a shock strut stroke associated with the secondary chamber nominal pressure, calculating, by the controller, a volume of oil in an oil chamber, a volume of gas in a primary gas chamber, a number of moles of gas in the primary gas chamber, a volume of oil leaked into the primary gas chamber, a volume of gas in a secondary chamber, and a number of moles of gas in the secondary chamber.

Abstract: A method for monitoring a dual-stage, separated gas/fluid shock strut includes receiving, by a controller, primary chamber temperature and pressure sensor readings, secondary chamber pressure and temperature sensor readings, and a shock strut stroke sensor reading, determining, by the controller, a shock strut stroke at which a secondary chamber is activated, calculating, by the controller, a volume of oil in an oil chamber of the shock strut, a primary chamber gas volume of, a number of moles of gas in, and a volume of oil leaked into, a primary gas chamber of the shock strut, a secondary chamber gas volume in, a volume of oil leaked into, and a number of moles of gas in, the secondary chamber, based upon at least one of the secondary chamber pressure sensor reading, and the secondary chamber temperature sensor reading.

Abstract: A system and various methods for determining a center of mass of an aircraft with a plurality of shock strut assemblies is illustrated. Multiple sensors, including a gas pressure sensor, and/or a position sensor, may be used to gather data and determine the center of mass of the aircraft. Various methods illustrated herein may evaluate the center of mass relative to a wheelbase axis and a wheel tread axis based on the gathered data.

Abstract: A method for weight off wheel shock strut servicing includes deflating the shock strut, compressing the shock strut via a jack until the shock strut is in a compressed position, charging the shock strut with an oil until a pressure of the oil reduces a volume of a residual air located inside of the shock strut, lowering the jack until a shock strut piston reaches a pre-determined extension, and charging the shock strut with a gas until the gas comprises a pre-determined pressure.

Abstract: An uplock system includes a cam plate comprising a cam channel, a hook configured to rotate with respect to the cam plate, a follower rotatably coupled to the hook, wherein a portion of the follower moves within the cam channel in response to rotation of the hook, a stopper configured to engage the follower, and a first biasing member configured to bias the stopper towards the follower to stop the follower from moving within the cam channel, thereby locking the hook in a locked position.

Abstract: A system and various methods for determining a center of mass of an aircraft with a plurality of shock strut assemblies is illustrated. Multiple sensors, including a gas pressure sensor, and/or a position sensor, may be used to gather data and determine the center of mass of the aircraft. Various methods illustrated herein may evaluate the center of mass relative to a wheelbase axis and a wheel tread axis based on the gathered data.

Abstract: A system for controlling landing gear subsystems may comprise a controller and a first motor drive unit in operable communication with the controller. A first electric motor and a second electric motor may be in operable communication with the first motor drive unit. A second motor drive unit may be in operable communication with the controller. A third electric motor and a fourth electric motor may be in operable communication with the second motor drive unit. An AC/DC converter may be electrically coupled to the first drive unit and the second motor drive unit.

Abstract: A nose landing gear system is disclosed. In various embodiments, the nose landing gear system includes an electro-hydraulic actuator configured to raise and lower a nose shock strut assembly; a first electro-mechanical actuator configured to steer the nose shock strut assembly; and a second electro-mechanical actuator configured to open and close a fairing door.

Abstract: A method for servicing a dual-stage, mixed gas/fluid shock strut may comprise measuring a servicing temperature, charging a secondary gas chamber with compressed gas, wherein a secondary chamber pressure corresponds to the servicing temperature, pumping oil into a primary chamber of the shock strut, and charging the primary chamber with compressed gas.

Abstract: A nose landing gear system is disclosed. In various embodiments, the nose landing gear system includes an electro-hydraulic actuator configured to raise and lower a nose shock strut assembly; a first electro-mechanical actuator configured to steer the nose shock strut assembly; and a second electro-mechanical actuator configured to open and close a fairing door.