AIRCRAFT SHOCK STRUT HAVING A FLUID LEVEL MONITOR

• US 20100017052A1
• Filed: 09/29/2009
• Published: 01/21/2010
• Est. Priority Date: 07/26/2005
• Status: Active Grant

• Current Assignee: Goodrich Corporation (Rtx Corporation)
• Original Assignee: Goodrich Corporation (Rtx Corporation)
• Inventors: Luce, William E.
• Granted Patent: US 8,528,400 B2
• Time in Patent Office: Days
• US Class Current: 701/16
• CPC Class Codes: B64C 25/60 Oleo legs
• CPC Class Codes: G01F 23/2922 with light-conducting sensing elements, e.g. prisms
• CPC Class Codes: G01F 23/2925 using electrical detecting means
• CPC Class Codes: G01F 25/20 of apparatus for measuring liquid level
• CPC Class Codes: G01F 25/24 Testing proper functioning of electronic circuits
• CPC Class Codes: G01M 11/31 with a light emitter and a light receiver being disposed at the same side of a fibre or waveguide end-face, e.g. reflectometers
• CPC Class Codes: G01M 3/3245 using a level monitoring device G01M3/3272 takes precedence

Abstract

A system for monitoring a liquid level in an aircraft shock strut includes a cylinder having an internal chamber sealed by a piston telescopically movable within the cylinder. The chamber contains a gas and a liquid, and a sensor assembly is provided for monitoring a condition of a level of the liquid in the chamber. The sensor assembly includes at least one probe within the chamber, and a fitting assembly allows one or more leads from the probe to pass through the wall of the strut while maintaining pressure in the chamber. The fitting assembly includes a plug molded to the one or more leads extending from the probe. The fitting assembly also includes a retainer for holding the plug in sealed relationship with a through passage in the strut.

Claims

1. A method of checking for damaged optical fibers or sensors in a liquid level sensing system, the method comprising:

transmitting a light beam down a first fiber that is optically coupled to a second fiber by a reflecting mechanism;

reflecting the light beam from the reflecting mechanism through the second fiber toward a light sensor; and

determining whether at least one of the fibers or sensors are damaged by;

checking a first reading of the light sensor when probe tips of both the first and second fibers are not submerged in a liquid;

checking a second reading of the light sensor when the probe tips are knowingly submerged in the liquid; and

comparing the first reading to the second reading.

2. The method of claim 1, further comprising providing a damaged fiber indication when the first reading is the same as the second reading and both readings provide a closed circuit indication.

3. The method of claim 1, further comprising providing a damaged sensor indication when the first reading is the same as the second reading and both readings provide an open circuit indication.

4. The method of claim 1, further comprising providing a functional indication when the first reading is opposite the second reading.

5. A method of monitoring a liquid level in an aircraft shock strut of a landing gear system, the method comprising:

detecting a liquid level with a plurality of probes that extend into the shock strut, the plurality of probes having at least a first probe extending by a first distance and a second probe extending by a different distance into the shock strut, each probe having a probe tip with a respective liquid level sensitivity range;

transmitting signals from the probes to a processor, the signals indicative of a present level of the liquid;

determining whether the liquid level is between the sensitivity range of the first probe tip;

when the liquid level is within the sensitivity range of the first probe tip, monitoring an amount of time required for the liquid level to transition from one probe tip to about the other probe tip; and

based on the amount of time, estimating a liquid loss rate per flight.

6. The method of claim 5, further comprising predicting an approximate number of flights remaining, based on the estimated liquid loss rate, before the liquid level reaches a lowermost threshold level.

7. The method of claim 5, further comprising:

determining a number of flights from an initially identified flight to a subsequently identified flight based on the estimated liquid loss rate; and

based on the number of flights, predicting the liquid level of a future flight occurring after the subsequently identified flight.

8. The method of claim 5, wherein detecting the liquid level with the plurality of probes includes arranging the probe tips to be in submergible contact with the liquid when the shock strut is in a static, deployed configuration and arranging the probe tips to be out of submergible contact with the liquid when the shock strut is in a retracted position.

9. The method of claim 5, further comprising transmitting intermittent signals to the processor when the liquid level is proximate the first probe.

10. The method of claim 5, wherein transmitting the signals includes transmitting light through optical fibers coupled to the plurality of probes.

11. A system for detecting damaged optical fibers or sensors in a liquid level sensing system, the system comprising:

a light sensor;

a reflecting mechanism;

first and second fibers optically coupled together through the reflecting mechanism, the fibers configured to reflect a light beam from the reflecting mechanism toward the light sensor; and

a processor to determine whether at least one of the fibers or sensors are damaged by;

processing a first signal received by the light sensor when the probe tips of both fibers are not submerged in a liquid;

processing a second signal received by the light sensor when the probe tips of both fibers should be knowingly submerged in the liquid; and

comparing the processed signals.