초록 ▼

An isolation method and system is described for distinguishing between turbine case cooling (TCC) and high pressure turbine (HPT) performance faults. A trend is observed in gas path parameter data during cruise and a resulting percent Δ signature across the shift in the gas path parameters is

An isolation method and system is described for distinguishing between turbine case cooling (TCC) and high pressure turbine (HPT) performance faults. A trend is observed in gas path parameter data during cruise and a resulting percent Δ signature across the shift in the gas path parameters is assignable to either an HPT or TCC performance fault. During either fault, exhaust gas temperature (EGT) will shift upward. Since take-off EGT margin is calculated from take-off data, the shift, or lack of shift in EGT margin may be used to differentiate between TCC and HPT faults.

대표청구항 ▼

What is claimed is: 1. A method for distinguishing between gas turbine engine case cooling (TCC) and high pressure turbine (HPT) performance faults comprising: monitoring a plurality of gas path parameters of an operating gas turbine engine so as to acquire in-flight gas path data samples from said

What is claimed is: 1. A method for distinguishing between gas turbine engine case cooling (TCC) and high pressure turbine (HPT) performance faults comprising: monitoring a plurality of gas path parameters of an operating gas turbine engine so as to acquire in-flight gas path data samples from said gas turbine engine, said in-flight gas path data samples corresponding to a predetermined number of engine parameter percent Δs from nominal; inputting said in-flight gas path data samples into a computer; determining if a percent Δ shift has occurred in a gas path engine parameter percent Δ; if a percent Δ signature shift has occurred, determining whether a shift ΔΔ is from an HPT or TCC performance fault, said shift ΔΔ determining step comprising: extracting exhaust gas temperature shift magnitudes from the predetermined number of engine parameters; converting said exhaust gas temperature shift magnitudes from percent to degrees; obtaining take-off EGT margin calculations for present flight time and previous flight time; calculating an exhaust gas temperature differential between in-flight and take-off exhaust gas temperature margin calculations, wherein the exhaust gas temperature differential is the difference between the change in exhaust gas temperature margin and the exhaust gas temperature shift magnitudes; calculating a TCC event likelihood and a non-TCC event likelihood; obtaining a mean and standard deviation for gas turbine engines not experiencing TCC faults; obtaining a mean and standard deviation for gas turbine engines experiencing TCC faults; and calculating an exhaust gas temperature difference between cruise and take-off conditions comparing said calculated TCC event likelihood to said calculated non-TCC event likelihood; and declaring a TCC performance fault if the calculated TCC event likelihood is greater than or equal to the calculated non-TCC event likelihood, wherein calculating the likelihood of a TCC or non-TCC event further comprises: obtaining a mean and standard deviation for gas turbine engines not experiencing TCC faults; obtaining a mean and standard deviation for gas turbine engines experiencing TCC faults, and calculating an exhaust gas temperature difference between cruise and take-off conditions. 2. The method according to claim 1 wherein the step of determining whether the shift is from an HPT or TCC performance fault further comprises: obtaining take-off exhaust gas temperature margin calculations for the present flight and from a previous flight; and calculating a change in exhaust gas temperature margin calculations between the present flight and a previous flight. 3. The method according to claim 1 further comprising trending the predetermined number of gas path engine parameters while in-flight. 4. The method according to claim 1 wherein EGT margin is a delta between the observed (takeoff) EGT and a pre-defined threshold. 5. The method according to claim 4 wherein a positive margin indicates that the engine is within the pre-defined threshold value. 6. The method according to claim 5 wherein a zero or negative margin indicates that the engine requires maintenance. 7. The method according to claim 6 wherein ΔEGT margin is approximately the same, but having opposite polarity, as the ΔEGT shift magnitude when TCC is not an underlying problem. 8. The method according to claim 7 further comprising calculating confidence metrics for TCC event likelihoods and non-TCC event likelihoods to obviate the effect of measurement non-repeatability. 9. The method according to claim 8 wherein the confidence metrics is a fuzzy confidence measure.