Method and system for identifying gas turbine engine faults

• US 20080147290A1
• Filed: 12/18/2006
• Published: 06/19/2008
• Est. Priority Date: 12/18/2006
• Status: Active Grant

• Current Assignee: Raytheon Technologies Corporation d/b/a RTX
• Original Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Volponi, Allan J.
• Granted Patent: US 7,702,447 B2
• Time in Patent Office: Days
• US Class Current: 701/100
• CPC Class Codes: F02C 9/00 Controlling gas-turbine plants; Controlling fuel supply in air- breathing jet-propulsion plants controlling air intakes F02C7/057; controlling turbines F01D; controlling compressors F04D27/00; controlling in general G05
• CPC Class Codes: F05D 2260/80 Diagnostics
• CPC Class Codes: F05D 2270/707 fuzzy logic
• CPC Class Codes: G05B 23/0278 Qualitative, e.g. if-then rules; Fuzzy logic; Lookup tables; Symptomatic search; FMEA

Abstract

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.

Claims

1. A method for distinguishing between gas turbine engine case cooling (TCC) and high pressure turbine (HPT) performance faults comprising:

acquiring in-flight gas path data samples corresponding to a predetermined number of engine parameter percent As from nominal;

determining if a percent A shift has occurred in a gas path engine parameter percent A;

if a percent A signature shift has occurred, determining whether the shift AA is from an HPT or TCC performance fault comprising;

extracting exhaust gas temperature shift magnitudes from the predetermined number of engine parameters;

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; and

calculating a TCC event likelihood and a non-TCC event likelihood, wherein if the TCC event is greater than or equal to the non-TCC event likelihood, declaring a TCC fault.

2. The method according to claim 1 wherein 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 2 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.

4. The method according to claim 3 further comprising trending the predetermined number of gas path engine parameters while in-flight.

5. The method according to claim 4 further comprising converting the exhaust gas temperature shift magnitudes from a percent measurement to degrees.

6. The method according to claim 5 wherein EGT margin is a delta between the observed (takeoff) EGT and a pre-defined threshold.

7. The method according to claim 6 wherein a positive margin indicates that the engine is within the pre-defined threshold value.

8. The method according to claim 7 wherein a zero or negative margin indicates that the engine requires maintenance.

9. The method according to claim 8 wherein TCC is not active during take-off.

10. The method according to claim 9 wherein Δ

EGT margin is approximately the same, but having opposite polarity, as the Δ

EGT shift when TCC is not an underlying problem.

11. The method according to claim 10 further comprising calculating confidence metrics for TCC event likelihoods and non-TCC event likelihoods to obviate the effect of measurement non-repeatability.

12. The method according to claim 11 wherein the confidence metrics may be a fuzzy confidence measure.