Abstract: A method and a system is provided, useable in electrical control sensors for shaft speed signal frequency change rate tests, detecting intermittent or “in-range”failures. The method estimates a short-term variance of the measured signal or signal rate of change, using the equation: Var[x]=E[x2]?E2[x], where E[x2] is an estimated average of the squared measured signal or rate of change over the short term, and E2[x] is a squared estimated average of the measured signal or rate of change over the short term. The estimated variance is compared with a predefined variance limit for a predefined amount of time, and if the estimated variance exceeds the predefined variance limit for the predefined amount of time, the measured signal is deemed invalid. A latching counter is used for timing, and its time out rate is preferably proportional to the time period the measured input is true. The step for estimating a short-term variance of the measured signal uses several filters performing averaging function.

Abstract: A method and system for surge detection within a gas turbine engine, comprises: measuring the compressor discharge pressure (CDP) of the gas turbine over a period of time; determining a time derivative (CDPD ) of the measured (CDP) correcting the CDPD for altitude, (CDPDCOR); estimating a short-term average of CDPDCOR2; estimating a short-term average of CDPDCOR; and determining a short-term variance of corrected CDP rate of change (CDProc) based upon the short-term average of CDPDCOR and the short-term average of CDPDCOR2. The method and system then compares the short-term variance of corrected CDP rate of change with a pre-determined threshold (CDPproc) and signals an output when CDProc>CDPproc. The method and system provides a signal of a surge within the gas turbine engine when CDProc remains>CDPproc for pre-determined period of time.

Abstract: A method and system for surge detection within a gas turbine engine, comprises: measuring the compressor discharge pressure (CDP) of the gas turbine over a period of time; determining a time derivative (CDPD) of the measured (CDP); correcting the CDPD for altitude, (CDPDCOR); estimating a short-term average of CDPDCOR2; estimating a short-term average of CDPDCOR; and determining a short-term variance of corrected CDP rate of change (CDProc) based upon the short-term average of CDPDCOR and the short-term average of CDPDCOR2. The method and system then compares the short-term variance of corrected CDP rate of change with a pre-determined threshold (CDPproc) and signals an output when CDProc>CDPproc. The method and system provides a signal of a surge within the gas turbine engine when CDProc remains >CDPproc for pre-determined period of time.

Abstract: A method and a system is provided, useable in electrical control sensors for shaft speed signal frequency change rate tests, detecting intermittent or “in-range” failures. The method estimates a short-term variance (standard deviation) of the measured signal or signal rate of change, using the equation: Var[x]=E[x2]−E2[x], where E[x2] is an estimated average of the squared measured signal or rate of change over the short term, and E2[x] is a squared estimated average of the measured signal or rate of change over the short term. The estimated variance is compared with a predefined variance limit for a predefined amount of time, and if the estimated variance exceeds the predefined variance limit for the predefined amount of time, the measured signal is deemed invalid. A latching counter is used for timing, and its time out rate is preferably proportional to the time period the measured input is true.

Abstract: Improved methods and systems are provided for detecting surge bleed valve faults and analyzing the performance of surge bleed valves in gas turbines. The method includes monitoring the rates of rotation of an engine fan and an engine gas generator in a gas turbine engine. While so doing, a valve status change signal is transmitted to a surge bleed valve in the gas turbine engine. The difference between the two monitored rates of rotation is determined. A surge bleed valve fault signal is generated if the difference between the two monitored rates of rotation does not change by at least a predetermined amount immediately following transmission of the valve status change signal to the surge bleed valve.

Abstract: Improved methods and systems are provided for detecting surge bleed valve faults and analyzing the performance of surge bleed valves in gas turbines. The method includes monitoring the rates of rotation of an engine fan and an engine gas generator in a gas turbine engine. While so doing, a valve status change signal is transmitted to a surge bleed valve in the gas turbine engine. The difference between the two monitored rates of rotation is determined. A surge bleed valve fault signal is generated if the difference between the two monitored rates of rotation does not change by at least a predetermined amount immediately following transmission of the valve status change signal to the surge bleed valve.

Abstract: A method and a system is provided, useable in electrical control sensors for shaft speed signal frequency change rate tests, detecting intermittent or “in-range” failures. The method estimates a short-term variance (standard deviation) of the measured signal or signal rate of change, using the equation: Var[x]=E[x2]−E2[x], where E[x2] is ] is an estimated average of the squared measured signal or rate of change over the short term, and E2[x] is a squared estimated average of the measured signal or rate of change over the short term. The estimated variance is compared with a predefined variance limit for a predefined amount of time, and if the estimated variance exceeds the predefined variance limit for the predefined amount of time, the measured signal is deemed invalid. A latching counter is used for timing, and its time out rate is preferably proportional to the time period the measured input is true.