LOAD MONITOR RELIABILITY FACTOR USING AN ADVANCED FATIGUE RELIABILITY ASSESSMENT MODEL

• US 20100235109A1
• Filed: 03/16/2010
• Published: 09/16/2010
• Est. Priority Date: 03/16/2009
• Status: Active Grant

• Current Assignee: Sikorsky Aircraft Corporation (Martin Marietta Corporation)
• Original Assignee: Sikorsky Aircraft Corporation (Martin Marietta Corporation)
• Inventors: Adams, David O., Zhao, Jack Z.
• Granted Patent: US 8,571,814 B2
• Time in Patent Office: Days
• US Class Current: 702/34
• CPC Class Codes: B64D 2045/0085 Devices for aircraft health monitoring, e.g. monitoring flutter or vibration
• CPC Class Codes: B64F 5/60 Testing or inspecting aircraft components or systems
• CPC Class Codes: G01M 5/00 Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings G01M9/00 takes precedence
• 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
• CPC Class Codes: G06Q 10/20 Administration of product repair or maintenance

Abstract

According to one non-limiting embodiment, a method includes accessing distributions of flight loads associated with one or more flight regimes for a fleet of aircraft. Using the distributions of flight loads, a factor for at least one of the flight regimes is determined that provides a flight load adjustment for a component on each aircraft of a fleet of aircraft known to be affected through at least load damage by the at least one flight regime.

Claims

1. A method comprising:

accessing distributions of flight loads associated with one or more flight regimes for a fleet of aircraft; and

determining, using the distributions of flight loads, a factor for at least one of the flight regimes that provides a flight load adjustment for a component on each aircraft of a fleet of aircraft known to be affected through at least load damage by the at least one flight regime.

2. The method as recited in claim 1, wherein the distributions include a plurality of flight loads, the method further including:

multiplying the plurality of flight loads by the factor to provide a flight load adjustment such that the flight load adjustment maintains the same level of structural reliability provided by a conventional component life calculation using “

high-envelope”

flight loads.

3. The method as recited in claim 1, wherein the distributions include a plurality of flight loads, the method further including:

verifying that the factor achieves a 0.999999 fatigue reliability.

4. The method as recited in claim 1, the method further including:

dividing a retirement damage level for the component by the factor.

5. The method as recited in claim 1, modifying a lifetime of the component for a selected one of the aircraft of the fleet in response to the factor.

6. The method as recited in claim 1, wherein said determining, using the distributions of flight loads, a factor for at least one of the flight regimes that provides a flight load adjustment for a component on each aircraft of a fleet of aircraft known to be affected through at least load damage by the at least one flight regime includes:

A) identifying a critical flight regime from the occurrence distribution;

B) determining a 99th percentile flight load value for the critical flight regime in the occurrence distribution;

C) determining a 50th percentile flight load value for the critical flight regime in the occurrence distribution; and

D) defining the factor as a ratio between the 99th percentile and 50th percentile flight load values for the critical flight regime.

7. The method as recited in claim 6, wherein said determining, using the distributions of flight loads, a factor for at least one of the flight regimes that provides a flight load adjustment for a component on each aircraft of a fleet of aircraft known to be affected through at least load damage by the at least one flight regime includes:

E) selectively repeating steps (A)-(D) for each of a plurality of critical flight regimes; and

F) defining the factor as a weighted average of factors for individual critical flight regimes.

8. The method as recited in claim 6, wherein said identifying a critical flight regime from the occurrence distribution includes identifying a flight regime as a critical flight regime in response to the flight regime having a rate of damage with measured loads that exceeds a predefined threshold.

9. The method as recited in claim 1, wherein said determining, using the distributions of flight loads, a factor for at least one of the flight regimes that provides a flight load adjustment for a component on each aircraft of a fleet of aircraft known to be affected through at least load damage by the at least one flight regime includes:

determining a Weibull plot of an actual distribution of flight loads for one of the flight regimes; and

defining the factor for a selected critical flight regime as a ratio between a 99th percentile Weibull plot flight loads value and a 50th percentile Weibull plot flight loads value for the flight regime.

10. The method as recited in claim 1, further including:

determining, using at least the factor, instructions to modify a lifetime of the component for a selected one of the aircraft from the fleet; and

communicating the instructions to an entity configured to use the instructions to modify the lifetime of the component.

11. The method as recited in claim 10, wherein the instructions comprise signals on a computer readable medium configured to cause a computer on the selected aircraft to adjust a lifetime of the component by the factor.

12. The method as recited in claim 10, further comprising displaying indicia corresponding to the lifetime of the component to a user of the selected helicopter.

13. The method as recited in claim 10, wherein the instructions facilitate adjustment to the lifetime of the component.

14. The method as recited in claim 10, wherein the method is performed on a computer remote from the aircraft.

15. An apparatus comprising a computer configured through computer readable instructions to perform the operations of:

determining a fatigue reliability of an aircraft component in response to at least one of flight usage data, flight load data, historical data, and a fatigue reliability assessment model; and

determining, using distributions of flight loads, a factor for at least one of the flight regimes that provides a flight load adjustment for the component for each aircraft of a fleet known to be affected through at least load damage by the at least one flight regime.

16. The apparatus as recited in claim 15, further comprising:

modifying a lifetime of the component for a selected one of the aircraft from the fleet in response to the factor.

17. The apparatus as recited in claim 16, wherein said modifying a lifetime of the component for a selected one of the aircraft from the fleet in response to the factor includes at least one of multiplying a plurality of load damage counts by the factor or dividing a retirement damage level by the factor.

18. A method performed by a computer either on-board or remote from an aircraft, comprising:

receiving a flight loads reliability factor associated with a component on an aircraft;

multiplying aircraft flight loads by the factor to determine adjusted flight loads;

adjusting, using at least the factor, a lifetime of the component in response to the adjusted flight loads; and

displaying the adjusted lifetime of the component.

19. The method of claim 18, wherein said receiving a flight loads reliability factor associated with a component on an aircraft includes receiving a single factor for a plurality of flight regimes, and said multiplying aircraft flight loads by the factor to determine adjusted flight loads includes multiplying aircraft flight loads for a plurality of flight regimes by the single factor.

20. The method of claim 18, wherein said receiving a flight loads reliability factor associated with a component on an aircraft includes receiving a factor for each of a plurality of flight regimes, and wherein said multiplying aircraft flight loads by the factor to determine adjusted flight loads includes multiplying each aircraft flight load for a given flight regime by the factor associated with that flight regime.