# US 10,865,848 B2 · Dual-stage, separated gas/fluid shock strut servicing

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- Number: US 10,865,848 B2
- Document ID: US10865848B2
- Status: Granted
- Kind: B2
- Application number: 15/642,081
- Filed: 2017-07-05
- Published: 2019-01-10
- Granted: 2020-12-15
- Earliest claimed: 2017-07-05
- Assignees: Goodrich Corporation
- Applicants: Goodrich Corporation
- Inventors: Amir Fazeli; Adnan Cepic; Susanne M. Reber
- Web page: https://patentgrep.com/patent/US10865848B2

## CPC

- F16F 9/43: Filling {or drainage} arrangements, e.g. for supply of gas {(filling vessels with, or discharging from vessels, compressed, liquefied, or solidified gases F17C)}
- B64C 25/60: Oleo legs
- B64F 5/40: Maintaining or repairing aircraft
- F16F 9/062: {Bi-tubular units}
- F16F 9/065: {Expansion chamber provided on the upper or lower end of a damper, separately there from or laterally on the damper}
- F16F 9/3292: {Sensor arrangements}
- F16F 9/437: {Drainage arrangements}
- F16F 9/063: {comprising a hollow piston rod}
- F16F 15/022: {using dampers and springs in combination}
- F16F 15/023: using fluid means
- F16F 2222/12: Fluid damping
- F16F 2230/46: Maintenance
- F16F 2236/045: the spring material being generally enclosed
- F16F: SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- B64C: AEROPLANES; HELICOPTERS
- B64F: GROUND OR AIRCRAFT-CARRIER-DECK INSTALLATIONS SPECIALLY ADAPTED FOR USE IN CONNECTION WITH AIRCRAFT; DESIGNING, MANUFACTURING, ASSEMBLING, CLEANING, MAINTAINING OR REPAIRING AIRCRAFT, NOT OTHERWISE PROVIDED FOR; HANDLING, TRANSPORTING, TESTING OR INSPECTING AIRCRAFT COMPONENTS, NOT OTHERWISE PROVIDED FOR

## Abstract

A method for servicing a dual-stage, separated gas/fluid shock strut may comprise measuring a servicing temperature, charging a secondary gas chamber with compressed gas, wherein a secondary chamber pressure corresponds to the servicing temperature, pumping oil into the shock strut, and charging a primary gas chamber with compressed gas.

## Claims

### Claim 1

A method for servicing a dual-stage, separated gas/fluid shock strut, comprising:
measuring a servicing temperature;
charging a secondary gas chamber with a first quantity of compressed gas, wherein a secondary chamber pressure corresponds to the servicing temperature;
pumping an oil into an oil chamber of the dual-stage, separated gas/fluid shock strut subsequent to the secondary gas chamber being charged with the first quantity of compressed gas; and
charging a primary gas chamber with a second quantity of compressed gas,
wherein the primary gas chamber is fluidly separated from the oil chamber via a first separator piston and the secondary gas chamber is fluidly separated from the oil chamber via a second separator piston.

### Claim 2 (depends on 1)

The method of claim 1, wherein the secondary gas chamber is charged with the second quantity of compressed gas until the secondary chamber pressure corresponds to the servicing temperature as indicated by a secondary chamber servicing chart.

### Claim 3 (depends on 1)

The method of claim 1, further comprising extending the dual-stage, separated gas/fluid shock strut in response to the pumping, wherein the dual-stage, separated gas/fluid shock strut extends such that a shock strut extension and the secondary chamber pressure match an oil servicing reference curve.

### Claim 4 (depends on 1)

The method of claim 1, further comprising:
extending the dual-stage, separated gas/fluid shock strut to a shock strut extension corresponding to the secondary chamber pressure, in accordance with an oil servicing reference curve, wherein the oil is pumped into the dual-stage, separated gas/fluid shock strut to a pre-determined pressure.

### Claim 5 (depends on 3)

The method of claim 3, wherein the oil servicing reference curve is provided in the form of at least one of a series of curves or a series of tables for various servicing temperatures.

### Claim 6 (depends on 1)

The method of claim 1, wherein the primary gas chamber is charged with the second quantity of compressed gas until a primary chamber pressure and a shock strut extension correspond to a primary chamber servicing reference curve.

### Claim 7 (depends on 1)

The method of claim 1, further comprising releasing a gas from the primary gas chamber.

### Claim 8 (depends on 1)

The method of claim 1, further comprising releasing a gas from the secondary gas chamber.

### Claim 9 (depends on 4)

The method of claim 4, wherein the pre-determined pressure is about 75 psi (517.1 kPa).

### Claim 10

A method for servicing a dual-stage, separated gas/fluid shock strut, comprising:
charging a secondary gas chamber with a first quantity of compressed gas, wherein a secondary chamber pressure corresponds to a servicing temperature;
pumping an oil into an oil chamber of the dual-stage, separated gas/fluid shock strut, wherein the dual-stage, separated gas/fluid shock strut extends until a first shock strut extension and the secondary chamber pressure match an oil servicing reference curve; and
charging a primary gas chamber with a second quantity of compressed gas until a second shock strut extension and a primary chamber pressure match a primary chamber servicing reference curve,
wherein the primary gas chamber is fluidly separated from the oil chamber via a first separator piston and the secondary gas chamber is fluidly separated from the oil chamber via a second separator piston.

### Claim 11 (depends on 10)

The method of claim 10, wherein at least one of the oil servicing reference curve and the primary chamber servicing reference curve correspond to the servicing temperature.

### Claim 12 (depends on 10)

The method of claim 10, further comprising measuring the servicing temperature.

### Claim 13 (depends on 10)

The method of claim 10, further comprising releasing a gas from the primary gas chamber.

### Claim 14 (depends on 10)

The method of claim 10, further comprising releasing a gas from the secondary gas chamber.

### Claim 15

A method for servicing a dual-stage, separated gas/fluid shock strut, comprising:
charging a secondary gas chamber with a first quantity of compressed gas, wherein a secondary chamber pressure corresponds to a servicing temperature;
circulating an oil through an oil chamber of the dual-stage, separated gas/fluid shock strut via an oil charge port and an oil bleed port;
extending the dual-stage, separated gas/fluid shock strut to a shock strut extension corresponding to the secondary chamber pressure according to an oil servicing reference curve;
closing the oil bleed port;
pumping the oil into the oil chamber until an oil chamber pressure reaches a pre-determined pressure while maintaining the shock strut extension;
closing the oil charge port;
extending the dual-stage, separated gas/fluid shock strut to a fully extended position; and
charging a primary gas chamber with a second quantity of compressed gas until a shock strut extension and a primary chamber pressure match a primary chamber servicing reference curve.

### Claim 16 (depends on 15)

The method of claim 15, wherein at least one of the oil servicing reference curve and the primary chamber servicing reference curve correspond to the servicing temperature.

### Claim 17 (depends on 15)

The method of claim 15, further comprising measuring the servicing temperature.

### Claim 18 (depends on 15)

The method of claim 15, wherein the pre-determined pressure comprises about 75 psi (517.1 kPa).

### Claim 19 (depends on 15)

The method of claim 15, further comprising releasing a gas from the primary gas chamber.

### Claim 20 (depends on 15)

The method of claim 15, further comprising releasing a gas from the secondary gas chamber.