Abstract: An example method of estimating a gas turbine engine surge margin and surge margin deterioration includes monitoring debris in at least a portion of an engine and establishing an estimated surge margin for the engine using information from the monitoring The method may use gas path parameters, such as pressures, temperatures, and speeds to establish the estimated surge margin. An example gas turbine engine surge margin assessment system includes a debris monitoring system configured to monitor debris moving through a portion of an engine, and a controller programmed to execute an engine deterioration model that establishes an estimated surge margin and loss in surge margin of the engine based on information from the debris monitoring system.

Abstract: An example method of estimating gas turbine engine performance deterioration includes monitoring debris in at least a portion of an engine and estimating performance deterioration of at least one component of the engine using information from the monitoring. The method may use gas path parameters, such as pressures, temperatures, and speeds to establish the estimated performance deterioration. An example gas turbine engine performance assessment system includes a debris monitoring system configured to monitor debris moving through a portion of an engine and a controller programmed to estimate performance deterioration of at least one component of the engine based on information from the debris monitoring system.

Abstract: An example method of assessing a component of a gas turbine engine includes monitoring debris in at least a portion of an engine and establishing an estimated thermal energy level for a component of the engine based on the monitoring. The method may use gas path parameters to establish the estimated thermal energy level. An example gas turbine engine component assessment system includes a debris monitoring system configured to monitor debris moving through a portion of an engine and a controller programmed to execute an engine deterioration model that assesses a thermal energy level of at least one component of the engine based on information from the debris monitoring system.

Abstract: A method for monitoring performance of an actuator is provided that includes the steps of: 1) determining an actuator response time constant in a control system, which actuator response time constant is representative of a task time taken by the actuator to complete a selected percentage of a task; 2) determining a rate of change of the actuator response time constant over a predetermined number of events; 3) determining a fault value indicative of when the actuator response time constant will equal or exceed an error time constant using the determined rate of change of the actuator response time constant; and 4) outputting a signal from the control system representative of the determined fault value.

Abstract: A fault reasoning system combines both a model-based reasoning approach based upon predicted root causes of a plurality of fault signals, and a case-based reasoner that looks at the actual root cause of actual cases.

Abstract: A method for conducting a repairable inventory analysis calculates the minimum number of repairable parts to be held in inventory while still being able to satisfy the demand for spare parts even in view of uncertain repair lead times. The method uses a set of equations that relates a customer service level to arbitrary probability distribution functions of a repair lead-time and a part arrival process. The distributions are then searched to locate the optimal inventory level in the distribution.

Abstract: A fault reasoning system combines both a model-based reasoning approach based upon predicted root causes of a plurality of fault signals, and a case-based reasoner that looks at the actual root cause of actual cases.

Abstract: Systems and methods involving engine models are provided. A representative method for updating a gas turbine engine reference model includes: determining whether an absolute difference between a dominant time constant of a sensor and an assumed sensor model time constant is outside a tolerance value; and responsive to determining that the absolute difference is outside the tolerance value, updating the assumed sensor model time constant with the dominant time constant of the sensor.

Abstract: A variable vane control system for use with a gas turbine engine includes a plurality of vanes, an actuation assembly, a mechanical linkage assembly, and a sensor. Each of the plurality of vanes has an airfoil portion disposed in a gas flowpath of the gas turbine engine, and a position of each of the vanes is adjustable with respect to an angle of attack of the airfoil portion of each vane. The actuation assembly is configured for generating actuation force to position the plurality of vanes. The mechanical linkage assembly operably connects the actuation assembly to at least one of the plurality of vanes. The sensor is configured to sense at least one of the position of the airfoil portions of the plurality of vanes and the mechanical linkage assembly, and to generate a position output signal.

Abstract: A process for optimizing maintenance work schedules for at least one engine includes the steps of retrieving at least one set of data for an engine from a computer readable storage medium; selecting at least one scheduling parameter for the engine; selecting a set of maintenance rules for the engine; selecting at least one maintenance work decision; selecting at least one objective for the engine; optimizing the at least one objective to generate at least one optimal maintenance work decision; and generating at least one optimal maintenance work schedule for the engine.

Abstract: A method of representing unscheduled events in a service plan includes retrieving unscheduled service event information relevant to a subject assembly and generating a service plan for the assembly that is responsive to the unscheduled service event information. A system for representing unscheduled service events in a service plan includes a computer system having means for retrieving unscheduled event information relevant to a subject assembly and means for generating a service plan for the assembly that is responsive to the unscheduled event information.

Abstract: Methods and apparatus for operating a gas turbine engine without sustained detrimental levels of dynamic pressure are provided. The engine includes a combustor. The method includes determining the combustor acoustic level amplitude, comparing the acoustic level to a predetermined upper acoustic limit, and adjusting a fuel flow distribution to the combustor using a closed loop controller to facilitate reducing the acoustic level to a predetermined lower acoustic limit that is less than the upper acoustic limit.

Abstract: A method for conducting a repairable inventory analysis calculates the minimum number of repairable parts to be held in inventory while still being able to satisfy the demand for spare parts even in view of uncertain repair lead times. The method uses a set of equations that relates a customer service level to arbitrary probability distribution functions of a repair lead-time and a part arrival process. The distributions are then searched to locate the optimal inventory level in the distribution.

Abstract: Methods and apparatus for operating a gas turbine engine without sustained detrimental levels of dynamic pressure are provided. The engine includes a combustor. The method includes determining the combustor acoustic level amplitude, comparing the acoustic level to a predetermined upper acoustic limit, and adjusting a fuel flow distribution to the combustor using a closed loop controller to facilitate reducing the acoustic level to a predetermined lower acoustic limit that is less than the upper acoustic limit.

Abstract: Critical stress in a gas turbine can be estimated using one or more readily measurable temperatures in the gas turbine. First and second critical temperatures can be estimated based on the at least one measurable temperature using heat conduction and convection equations. Subsequently, the critical stress can be estimated in real time according to a stress model prediction based on the difference between the critical temperatures, and possibly the rotational speed of the turbine, and some parameter, such as air pressure, that is indicative of air flow around the turbine component. Operation of the gas turbine can thus be controlled using the estimated critical temperatures.

Abstract: An on-line sensor is provided that supplies light to a spectrophotometer to measure the color a product extruded through a conduit having a bypass section. The on-line sensor includes a transparent member with an opaque outer surface and an interior portion extending from a first end to a second end to the transparent member. The interior portion is connected to the bypass section, and the product that flows through the bypass section is supplied to the interior section of the transparent member. A light source connected to the transparent member and provides light to the transparent member inside the opaque outer surface. A light receiver is connected to the transparent member and captures light from the light source in the transparent member that is affected by the product. The captured light is supplied to the spectrophotometer to at least measure the properties of the product supplied to the interior portion of the transparent member.

Abstract: Critical stress in a gas turbine can be estimated using one or more readily measurable temperatures in the gas turbine. First and second critical temperatures can be estimated based on the at least one measurable temperature using heat conduction and convection equations. Subsequently, the critical stress can be estimated in real time according to a stress model prediction based on the difference between the critical temperatures, and possibly the rotational speed of the turbine, and some parameter, such as air pressure, that is indicative of air flow around the turbine component. Operation of the gas turbine can thus be controlled using the estimated critical temperatures.

Abstract: A fault detection and isolation system for detecting leaks and blockages in a fluid handling system having at least one component through which fluid flows includes sensors for measuring fluid conditions upstream and downstream of the component. The sensors generate signals that are representative of the upstream and downstream fluid conditions and are fed to a control algorithm. The control algorithm uses the measured fluid conditions to generate estimates of an inlet state for the component and an outlet state for the component. The control algorithm also calculates innovation sequences for the estimated inlet and outlet states, and then compares the innovation sequences to predetermined thresholds to detect leaks and blockages.

Abstract: Shape of a long reach device, e.g., a welding torch, suitable for use within a portion of an object along a joint curve, e.g., a weld joint, is determined by dissecting the long reach device into a discrete number of portions, identifying ranges of movement between each of the portions, and discretizing the ranges of movement into a predetermined number of intervals. A total number of possible shapes is determined based on the total portions of the long reach device having the first movement range discretized into a predetermined number of intervals. A representation of the long reach device having one of the possible shapes is compared with the representation of the portion of the object.

Abstract: An on-line color sensor supplies light to a spectrophotometer for color measurement of product after cooling. The product is extruded in a main extruder having a bypass section. The on-line color sensor includes an housing having an interior portion. The housing is positioned proximate to the bypass section and is used to direct the product from the bypass section into the interior portion. A receptacle that is connected to the housing is positioned in the interior portion of the housing to hold the product directed into the interior portion. The product is allowed to cool while being held on the receptacle. A light source is connected to the housing and supplies light to the interior portion of the housing. A light receiver is connected to the housing to capture the light from the light source in the interior portion that is affected by the cooled product. The captured light is supplied to the spectrophotometer to measuring the color of the cooled product in the interior portion of the housing.