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 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 dual-stage, separated gas/fluid shock strut arrangement includes a dual-stage, separated gas/fluid shock strut, a pressure/temperature sensor mounted to the primary gas chamber, a stroke sensor, and a monitoring system, comprising a recorder configured to receive a plurality of sensor readings from at least one of the pressure/temperature sensor and the stroke sensor, a landing detector configured to detect a landing event based upon a stroke sensor reading received from the stroke sensor, and a health monitor configured to determine a volume of oil in the oil chamber, a volume of gas in the primary gas chamber, and a volume of gas in the secondary gas chamber.

Abstract: A dual-stage, separated gas/fluid shock strut arrangement includes a dual-stage, separated gas/fluid shock strut and a monitoring system. The shock strut includes a strut cylinder, a strut piston operatively coupled to the strut cylinder, an oil chamber, a primary gas chamber, and a secondary gas chamber. The monitoring system includes a first pressure/temperature sensor, a second pressure/temperature sensor, a stroke sensor, a recorder configured to receive a plurality of sensor readings from the first pressure/temperature sensor, the second pressure/temperature sensor, and/or the stroke sensor, a landing detector configured to detect a landing event based upon a stroke sensor reading received from the stroke sensor, and a health monitor configured to determine a volume of oil in the oil chamber, a primary chamber gas volume in the primary gas chamber, and a secondary chamber gas volume in the secondary gas chamber.

Abstract: A dual-stage, stroke activated, mixed fluid gas shock strut arrangement includes a dual-stage, stroke activated, mixed fluid gas shock strut (shock strut) and a monitoring system. The shock strut includes a strut cylinder, a strut piston, a primary chamber comprising an oil chamber and a primary gas chamber, and a secondary gas chamber. The monitoring system includes a first pressure/temperature sensor, a second pressure/temperature sensor, a stroke sensor, a recorder configured to receive a plurality of sensor readings from the first pressure/temperature sensor, the second pressure/temperature sensor, and/or the stroke sensor, a landing detector configured to detect a landing event based upon a stroke sensor reading received from the stroke sensor, and a health monitor configured to determine an oil volume in the primary chamber, wherein the health monitor calculates a compression factor to determine the oil volume.

Abstract: A monitoring system for a dual-stage, stroke activated, mixed fluid gas shock strut may comprise a controller, 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 various operations. Said operations may include calculating, by the controller, a compression factor, determining, by the controller, a plurality of compression factors for known oil volumes based on at least one of the primary chamber temperature sensor reading and the shock strut stroke sensor reading, and calculating, by the controller, an oil volume in a primary chamber of the shock strut.

Abstract: A monitoring system for a dual-stage, separated gas/fluid shock strut may comprise a controller 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 various operations. Said operations may include calculating, by the controller, a secondary chamber nominal pressure, 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 of the shock strut, calculating, by the controller, a volume of gas in a primary chamber of the shock strut, calculating, by the controller, a secondary chamber inflation pressure, and calculating, by the controller, a volume of oil leaked into the primary chamber of the shock strut.

Abstract: A monitoring system for a dual-stage, separated gas/fluid shock strut may comprise a controller 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 various operations. Said operations may include determining, by the controller, a shock strut stroke at which a secondary chamber of the shock strut is activated, calculating, by the controller, a volume of oil in an oil chamber of the shock strut, calculating, by the controller, a volume of gas in a primary chamber of the shock strut, and calculating, by the controller, a volume of oil leaked into the primary chamber of the shock strut.

Abstract: A monitoring system for a dual-stage, pressure-activated, mixed fluid gas shock strut, may comprise a controller, and a tangible, non-transitory memory configured to communicate with the controller, the tangible, non-transitory memory having instructions stored thereon that, in response to execution by the controller, cause the controller to perform operations comprising receiving, by the controller, a primary chamber temperature sensor reading, receiving, by the controller, a primary chamber pressure sensor reading, receiving, by the controller, a shock strut stroke sensor reading, and calculating, by the controller, an oil volume in a primary chamber of the shock strut. The instructions may cause the controller to perform further operations comprising calculating, by the controller, a number of moles of gas in a primary chamber of the shock strut and calculating, by the controller, a number of moles of gas in a secondary chamber of the shock strut.

Abstract: A monitoring system for a dual-stage, stroke activated, mixed fluid gas shock strut may comprise a controller, 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 various operations. Said operations may include calculating, by the controller, a compression factor, determining, by the controller, a plurality of compression factors for known oil volumes based on at least one of the primary chamber temperature sensor reading and the shock strut stroke sensor reading, and calculating, by the controller, an oil volume in a primary chamber of the shock strut.

Abstract: A method for servicing a dual-stage, separated 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 the shock strut, and charging a primary gas chamber with compressed gas.

Abstract: A monitoring system for a dual-stage, separated gas/fluid shock strut may comprise a controller 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 various operations. Said operations may include determining, by the controller, a shock strut stroke at which a secondary chamber of the shock strut is activated, calculating, by the controller, a volume of oil in an oil chamber of the shock strut, calculating, by the controller, a volume of gas in a primary chamber of the shock strut, and calculating, by the controller, a volume of oil leaked into the primary chamber of the shock strut.

Abstract: A monitoring system for a dual-stage, separated gas/fluid shock strut may comprise a controller 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 various operations. Said operations may include calculating, by the controller, a secondary chamber nominal pressure, 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 of the shock strut, calculating, by the controller, a volume of gas in a primary chamber of the shock strut, calculating, by the controller, a secondary chamber inflation pressure, and calculating, by the controller, a volume of oil leaked into the primary chamber of the shock strut.

Abstract: A method includes detecting at least one position measurement of a separator piston of a pitch trim actuator. The method includes detecting at least one pressure measurement of an oil. The method includes detecting at least one temperature measurement of the oil. The method includes storing at least one position value based on the at least one position measurement of the separator piston, at least one pressure value based on the at least one pressure measurement of the oil and at least one temperature value based on the at least one temperature measurement of the oil. The method includes determining whether the pitch trim actuator requires servicing based on the at least one position value, the at least one pressure value, and the at least one temperature value.

Abstract: A monitoring system for a dual-stage, pressure-activated, mixed fluid gas shock strut, may comprise a controller, and a tangible, non-transitory memory configured to communicate with the controller, the tangible, non-transitory memory having instructions stored thereon that, in response to execution by the controller, cause the controller to perform operations comprising receiving, by the controller, a primary chamber temperature sensor reading, receiving, by the controller, a primary chamber pressure sensor reading, receiving, by the controller, a shock strut stroke sensor reading, and calculating, by the controller, an oil volume in a primary chamber of the shock strut. The instructions may cause the controller to perform further operations comprising calculating, by the controller, a number of moles of gas in a primary chamber of the shock strut and calculating, by the controller, a number of moles of gas in a secondary chamber of the shock strut.

Abstract: A method includes detecting at least one position measurement of a separator piston of a pitch trim actuator. The method includes detecting at least one pressure measurement of an oil. The method includes detecting at least one temperature measurement of the oil. The method includes storing at least one position value based on the at least one position measurement of the separator piston, at least one pressure value based on the at least one pressure measurement of the oil and at least one temperature value based on the at least one temperature measurement of the oil. The method includes determining whether the pitch trim actuator requires servicing based on the at least one position value, the at least one pressure value, and the at least one temperature value.

Abstract: A method includes detecting at least one position measurement of a separator piston of a pitch trim actuator. The method includes detecting at least one pressure measurement of a gas. The method includes detecting at least one temperature measurement of the gas. The method includes storing at least one position value based on the at least one position measurement of the separator piston, at least one pressure value based on the at least one pressure measurement of the gas and at least one temperature value based on the at least one temperature measurement of the gas. The method includes determining a volume of an oil within an oil chamber of the pitch trim actuator and a pressure of the gas within the gas chamber of the pitch trim actuator, based on the at least one position value, the at least one pressure value and the at least one temperature value.

Abstract: A method of servicing a shock strut of a landing gear includes partially filling the shock strut with fresh oil and pressurizing the chamber with gas. The pressurizing is to a pressure level that compensates for expected gas pressure loss due to gas entrainment in the oil during operation of the shock strut. The method can be performed without weight on wheels, with weight on wheels and a constant strut stroke, or weight on wheels and a constant pressure.

Abstract: A method and system of monitoring condition of a shock strut senses gas temperature, gas pressure, and stroke of the strut during a landing event. Oil loss is determined based upon a deviation of a transient pressure coefficient derived from transient gas pressures at two different strokes from a nominal coefficient value. Gas loss is determined based upon a temperature adjusted transient gas pressure at a selected stroke and a nominal gas pressure value at the selected stroke.

Abstract: A method includes detecting at least one position measurement of a separator piston of a pitch trim actuator. The method includes detecting at least one pressure measurement of a gas. The method includes detecting at least one temperature measurement of the gas. The method includes storing at least one position value based on the at least one position measurement of the separator piston, at least one pressure value based on the at least one pressure measurement of the gas and at least one temperature value based on the at least one temperature measurement of the gas. The method includes determining a volume of an oil within an oil chamber of the pitch trim actuator and a pressure of the gas within the gas chamber of the pitch trim actuator, based on the at least one position value, the at least one pressure value and the at least one temperature value.