Method and apparatus for improving fault isolation

• US 6,748,304 B2
• Filed: 08/16/2002
• Issued: 06/08/2004
• Est. Priority Date: 08/16/2002
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Kolbet, David M., Stone, John F., van der Zweep, Jeff J., Felke, Timothy J.
• Primary Examiner(s): Nguyen, Thu V.
• Application Number:
  US10/222,397
• Publication Number:
  US 20040034456A1
• Time in Patent Office: 662 Days
• Field of Search: 701/29-31, 701/33-35, 340/945
• US Class Current: 701/29
• CPC Class Codes: B64F 5/60 Testing or inspecting aircraft components or systems
• CPC Class Codes: G05B 23/0278 Qualitative, e.g. if-then rules; Fuzzy logic; Lookup tables; Symptomatic search; FMEA
• CPC Class Codes: G06Q 10/04 Forecasting or optimisation specially adapted for administrative or management purposes, e.g. linear programming or "cutting stock problem" market predictions or forecasting for commercial activities G06Q30/0202

Abstract

A method for improving fault isolation for failure modes in complex systems, and a software program embodying the method or a corresponding method together with a computer based aircraft diagnostic system using such software is described. The method includes: capturing a set of symptoms that is consistent with a failure mode of the complex system; identifying a set of repairs for the complex system that are consistent with the set of symptoms; ranking, when the set of repairs includes more than one repair, the repairs in a sequence that will minimize an average cost to repair the complex system, the sequence including a historical component and reflecting the effectiveness of available test results to resolve each the repairs; determining possible tests that are consistent with the failure mode; and ranking the possible tests according to there respective net improvement in the average cost to repair the complex system.

Claims

1. A method for improving fault isolation for failure modes in a complex system, the method including the steps of:

capturing a set of symptoms that is consistent with a failure mode of the complex system;

identifying a set of repairs for the complex system that are consistent with said set of symptoms;

ranking, when said set of repairs includes more than one repair, said repairs in a sequence that will minimize an average cost to repair the complex system;

determining possible tests that are consistent with said failure mode; and

ranking said possible tests according to their respective net improvement in said average cost to repair the complex system.

2. The method of claim 1 further including a step of selecting a test and obtaining a test result from said possible tests and repeating, using said set of symptoms, said test result, and any additional test results for tests that will be selected, said steps of identifying, ranking said set of repairs, determining said possible tests, ranking said possible tests and selecting further tests until said set of repairs includes only one repair and then reporting said repair.

3. The method of claim 1 wherein said step of capturing said set of symptoms includes using a standard code as an indication of a set of standard observations corresponding to a subset of observable symptoms from said set of symptoms, said standard observations selected from a standard observations list, and wherein the step of determining possible tests that are consistent with said failure mode comprises determining said possible tests corresponding to said standard code and wherein said step of identifying said set of repairs includes identifying a list of repairs corresponding to said standard code for said set of symptoms.

4. The method of claim 1 wherein said step of ranking said repairs further uses an assessment of experience with said set of symptoms occurring with each repair of said set of said repairs, and further uses whether said available test results indict, acquit, or are silent with respect to said each repair, and further uses a cost associated with each repair.

5. The method of claim 1 wherein said ranking said possible tests uses an algorithm to rank said possible tests according to a value of said possible test that is dependent on a reduction in said average cost minus a cost to conduct said possible test.

6. The method of claim 1 wherein the complex system comprises an aircraft.

7. A software program comprising software instructions arranged to run on a processor to improve fault isolation for failure modes in a complex system, the software program when installed and operating on a processor resulting in the processor:

capturing a set of symptoms that is consistent with a failure mode of the complex system;

identifying a set of repairs for the complex system that are consistent with said set of symptoms;

ranking, when said set of repairs includes more than one repair, said repairs in a sequence that will minimize an average cost to repair the complex system;

determining possible tests that are consistent with said failure mode; and

ranking said possible tests according to their respective net improvement in said average cost to repair the complex system.

8. The software program of claim 7 further including selecting a test and obtaining a test result from said possible tests and repeating, using said set of symptoms, said test result, and any test results from additional tests that will be selected, said identifying, said ranking said set of repairs, said determining said possible tests, said ranking said possible tests and said selecting tests until said set of repairs includes only one repair and then reporting said repair.

9. The software program of claim 7 wherein said capturing said set of symptoms includes using a standard code as an indication of a set of standard observations corresponding to a subset of observable symptoms from said set of symptoms, said standard observations selected from a standard observations list and wherein said determining possible tests that are consistent with said failure mode comprises determining possible tests that correspond to said standard code and wherein said identifying said set of said repairs includes identifying a list of repairs corresponding to said standard code for said set of symptoms.

10. The software program of claim 7 wherein said ranking said repairs further uses an assessment of experience with said set of symptoms occurring with each repair of said set of said repairs, and further uses whether said available test results indict, acquit, or are silent with respect to said each repair, and further uses a cost associated with each repair.

11. The software program of claim 7 wherein said ranking said possible tests uses an algorithm to rank said possible tests according to a value of said possible test that is dependent on a reduction in said average cost minus a cost to conduct said possible test.

12. The software program of claim 7 wherein the complex system comprises an aircraft.

13. An aircraft maintenance and operations diagnostic system for improved assistance with fault isolation for a fault condition within an aircraft based on a fault model for the aircraft, the system comprising in combination:

a user interface;

a computer, coupled to the user interface, having memory for storing software instructions and databases and a processor for;

executing said software instructions to process information to facilitate the fault isolation for the fault condition according to a fault model, the software program resulting in the computer;

capturing a fault code from a fault classification process, said fault code being part of the fault model that is consistent with the fault condition;

identifying a set of repairs for the aircraft that are consistent with said fault code;

ranking, when said set of repairs includes more than one repair, said repairs in a sequence that will minimize an average cost to repair the aircraft;

determining possible tests that are consistent with said fault code; and

ranking said possible tests according to their respective net improvement in said average cost to repair the aircraft.

14. The system of claim 13 further including selecting a test and obtaining a test result from said possible tests and repeating, using said fault code, said test result, and any test results from additional tests that will be selected, said identifying, said ranking said set of repairs, said determining said possible tests, said ranking said possible tests and selecting further tests until said set of repairs includes only one repair and then reporting said repair.

15. The system of claim 13 wherein said capturing said fault code includes capturing an associated set of standard observations corresponding to a subset of observable symptoms, and wherein said standard observations arc selected from a standard observations list and capturing any available test outcomes.

16. The system of claim 13 wherein said step of ranking said repairs further uses an assessment of experience with a set of symptoms, corresponding to observable symptoms associated with said fault code and any available test outcomes, occurring with each repair of said set of said repairs, whether said available test results indict, acquit, or are silent with respect to said each repair, and a cost associated with each repair.

17. The system of claim 13 wherein said ranking said possible tests uses an algorithm to rank said possible tests according to a value of said possible test that is dependent on a reduction in said average cost minus a cost to conduct said possible test.

18. The system of claim 13 further including displaying said possible tests as ranked on said user interface to facilitate reviewing and selecting a possible test.

19. The system of claim 13 further including a portal to a wide area network to provide diagnostic support for fault isolation to remote users.