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, 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 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, 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 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 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.

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 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.