Methods for establishing alerts and/or alert limits for monitoring mechanical devices

1. A method for establishing at least one of an alert or an alert limit for monitoring a mechanical device, said method comprising:

identifying faults that can be recognized by their effect on measured trends;

determining a set of available sensors for monitoring said trends;

acquiring and processing representative data to obtain a statistical characterization of said trends;

determining a parameter variance for at least one alert test in accordance with said statistical characterization;

analyzing Type I and Type II error risks and associated financial penalties to adjust parameters associated with the at least one alert test, wherein one Type I error risks represent the likelihood of false alerts, and wherein the Type II error risks represent the likelihood of missed alerts;

automatically programming an automated alert system to utilize the adjusted parameters to identify measured trends of a mechanical device that are to be brought to the attention of a human analyst.

2. A method in accordance with claim 1 further comprising identifying a test to be performed by the automated alert system that includes comparison of a monitored trend value to an absolute limit.

3. A method in accordance with claim 1 further comprising identifying a test to be performed by the automated alert system that includes recognition of a monitored trend value shift greater than a fixed limit.

4. A method in accordance with claim 1 wherein said processing of representative data comprises adjusting the data to a reference condition.

5. A method in accordance with claim 1 wherein said processing of representative data comprises computing an efficiency measure.

6. A method in accordance with claim 1 further comprising analyzing the alert parameters to determine a probability that an alert signals a true fault and adjusting alert limits in accordance to increase the probability that an alert signals a true fault.

7. A method for establishing at least one of an alert or an alert limit for monitoring a mechanical device, wherein the mechanical device is an aircraft engine, and said method comprises:

reviewing one or more manuals from the set consisting of engine manuals and aircraft manuals to identify faults that can be recognized by their effect on measured trends;

determining a set of available sensors for monitoring said trends;

acquiring and processing representative data to obtain a statistical characterization of said trends;

determining a parameter variance for at least one alert test in accordance with said statistical characterization;

analyzing Type I and Type II error risks and associated financial penalties to adjust parameters associated with the at least one alert test, wherein the Type I error risks represent the likelihood of false alerts and wherein the Type II error risks represent the likelihood of missed alerts;

automatically programming the automated alert system to utilize the adjusted parameters to identify measured trends of a mechanical device that are to be brought to the attention of a human analyst.

8. A method in accordance with claim 7 wherein said determining a set of available sensors for monitoring said trends further comprises determining flight conditions under which said monitored trends are to be available.

9. A method in accordance with claim 7 further comprising identifying a test to be performed by the automated alert system that includes comparison of a monitored trend value to an absolute limit.

10. A method in accordance with claim 7 further comprising identifying a test to be performed by the automated alert system that includes recognition of a monitored trend value shift greater than a fixed limit.

11. A method in accordance with claim 7 wherein said processing of representative data comprises adjusting the data to a reference condition.

12. A method in accordance with claim 11 wherein the reference condition is a reference flight condition.

13. A method in accordance with claim 12 wherein the reference flight condition includes a predetermined condition selected from the group consisting of altitude, Mach number, total air temperature, and bleed configuration.

14. A method in accordance with claim 11 wherein the reference condition further comprises a power setting.

15. A method in accordance with claim 7 wherein said processing of representative data comprises computing an efficiency measure.

16. A method in accordance with claim 7 wherein said acquiring and processing representative data to obtain a statistical characterization of said trends further comprises generating trends to be tested for alerts.

17. A method in accordance with claim 16 performed using a plurality of different engines and flight conditions.

18. A method in accordance with claim 17 wherein said parameter variance comprises a EGT deviation from baseline at cruise.

19. A method in accordance with claim 18 wherein said EGT deviation from baseline at cruise is determined for each said engine and combined into a fleet pooled value.

20. A method in accordance with claim 7 further comprising analyzing the alert parameters to determine a probability that an alert signals a true fault and adjusting alert limits in accordance to increase the probability that an alert signals a true fault.

21. A method in accordance with claim 20 wherein said analyzing the alert parameters comprises a Monte Carlo simulation.