Aircraft landing gear shock strut performance monitoring

Patent metadata

Field	Value
Publication number	US-9773357-B2
Application number	US-201414456632-A
Country	US
Kind code	B2
Filing date	Aug 11, 2014
Priority date	Mar 21, 2014
Publication date	Sep 26, 2017
Grant date	Sep 26, 2017

Abstract

A system and various methods for monitoring and evaluating the health of a shock strut assembly are illustrated. Multiple sensors, including gas temperature, gas pressure, oil pressure, and position sensor, may be used to gather data and evaluate the performance of the shock strut assembly. Various methods illustrated herein may evaluate the dynamic damping, static load support, and/or controlled stroke performance of the shock strut assembly.

First claim

What is claimed is:

1. A method for monitoring the performance of a shock strut system comprising:
providing a shock strut mechanically coupled to a landing gear assembly and comprising a position sensor configured to measure a stroke of the shock strut and an oil chamber pressure sensor configured to measure an oil pressure within the shock strut;
measuring the oil pressure by the oil chamber pressure sensor during a take-off phase;
measuring the stroke by the position sensor during the take-off phase;
determining a first performance factor of the shock strut by,
evaluating a minimum recorded oil pressure within the shock strut measured during the take-off phase and comparing the minimum recorded oil pressure to a threshold pressure to determine whether cavitation is present within the shock strut,
determining an impact speed of the shock strut by calculating an average extension rate of the stroke during an end stage of an extension stage during the take-off phase,
evaluating the impact speed of the shock strut during the end stage of the extension stage by comparing the impact speed to a threshold impact speed, and
evaluating an average stroke rate of the shock strut during the extension stage of the take-off phase and comparing the average stroke rate with a threshold extension rate; and

indicating by the first performance factor whether the shock strut is within an acceptable operating range for shock strut extension.

2. The method for monitoring the performance of a shock strut system of claim 1 , further comprising measuring by a gas pressure sensor a gas pressure in the shock strut before landing and after landing, measuring by a gas temperature sensor a gas temperature in the shock strut before landing and after landing, and measuring the stroke by the position sensor after landing.

3. The method for monitoring the performance of the shock strut system of claim 2 , further comprising evaluating an amount of gas dissolved in an oil of the shock strut based on the gas pressure measured after landing.

4. The method for monitoring the performance of the shock strut system of claim 3 , further comprising determining a static stroke of the shock strut at minimum operating temperature and maximum load and comparing the static stroke with a maximum stroke to determine a second performance factor of the shock strut.

5. The method for monitoring the performance of a shock strut system of claim 4 , wherein the second performance factor comprises a static load support capability of the shock strut.

6. The method for monitoring the performance of the shock strut system of claim 1 , further comprising evaluating a maximum transient stroke.

7. The method for monitoring the performance of the shock strut system of claim 6 , further comprising evaluating an amount of energy input to the shock strut.

8. The method for monitoring the performance of the shock strut system of claim 7 , further comprising evaluating a maximum transient load applied to an aircraft by the shock strut.

9. The method for monitoring the performance of the shock strut system of claim 8 , further comprising evaluating a shock strut efficiency.

10. The method for monitoring the performance of the shock strut system of claim 9 , further comprising comparing one of the maximum transient load, the maximum transient stroke, and the shock strut efficiency with one of a predetermined maximum transient load, a predetermined maximum transient stroke, and a predetermined shock strut efficiency to determine a third performance factor of the shock strut.

11. The method for monitoring the performance of a shock strut system of claim 10 , wherein the third performance factor comprises a dynamic damping performance of the shock strut.

12. A method for monitoring the performance of a shock strut system comprising:
providing a shock strut mechanically coupled to a landing gear assembly and comprising a position sensor configured to measure a stroke of the shock strut and an oil chamber pressure sensor configured to measure an oil pressure within the shock strut;
measuring a gas pressure within the shock strut by a gas pressure sensor and a gas temperature within the shock strut by a gas temperature sensor before a landing;
measuring the gas pressure within the shock strut by the gas pressure sensor, the gas temperature within the shock strut by the gas temperature sensor, and a stroke by the position sensor after the landing;
evaluating an amount of gas dissolved in an oil within the shock strut based on the gas pressure measured after the landing;
evaluating a static stroke of the shock strut for a minimum operating temperature and a maximum load on gear, the static stroke based on the gas pressure after the landing, the stroke after the landing and the amount of gas dissolved in the oil;
comparing the static stroke of the shock strut with a maximum stroke to determine a first performance factor of the shock strut; and
providing feedback indicating by the first performance factor whether the shock strut is within an acceptable operating range for static stroke.

13. The method for monitoring the performance of the shock strut of claim 12 , further comprising evaluating an amount of energy input to the shock strut.

14. The method for monitoring the performance of the shock strut of claim 13 , further comprising evaluating a maximum transient load applied to an aircraft by the shock strut.

15. The method for monitoring the performance of the shock strut of claim 14 , further comprising evaluating a shock strut efficiency.

16. The method for monitoring the performance of the shock strut of claim 15 , further comprising comparing one of the maximum transient load, a maximum transient stroke, and the shock strut efficiency with one of a predetermined maximum transient load, a predetermined maximum transient stroke, and a predetermined shock strut efficiency to determine a second performance factor of the shock strut.

17. The method for monitoring the performance of the shock strut of claim 16 , wherein the second performance factor comprises a dynamic damping performance of the shock strut.

18. The method for monitoring the performance of the shock strut of claim 12 , further comprising:
measuring the oil pressure by the oil chamber pressure sensor during a take-off phase;
measuring the stroke by the position sensor during the take-off phase;
evaluating a minimum recorded oil pressure within the shock strut measured during the take-off phase and comparing the minimum recorded oil pressure to a threshold pressure;
determining an impact speed of the shock strut by calculating an average extension rate of the stroke during an end stage of an extension stage during the take-off phase;
evaluating the impact speed of the shock strut by comparing the impact speed to a threshold impact speed; and
evaluating an average stroke rate of the shock strut during the extension stage and comparing the average stroke rate with a threshold extension rate to determine an extension performance of the shock strut.

19. The method for monitoring the performance of the shock strut of claim 12 , wherein the first performance factor comprises a static load support capability of the shock strut.

20. The method for monitoring the performance of a shock strut system of claim 1 , wherein the first performance factor comprises an extension performance of the shock strut.

Assignees

• Goodrich Corp

Inventors

• Fazeli Amir
• Cepic Adnan
• Reber Susanne

Classifications

• B64F5/60

  Testing or inspecting aircraft components or systems · CPC title

• G01M17/04

  Suspension or damping · CPC title

• A63B2220/40

  Acceleration · CPC title

• A42B3/0473

  Neck restraints · CPC title

• B64C25/60 Primary

  Oleo legs · CPC title