# US 11,078,936 B2 · Portable external oil cooler process for performing hydraulic system functional tests on unfueled airplanes

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- Number: US 11,078,936 B2
- Document ID: US11078936B2
- Status: Granted
- Kind: B2
- Application number: 16/431,192
- Filed: 2019-06-04
- Published: 2020-12-10
- Granted: 2021-08-03
- Earliest claimed: 2019-06-04
- Assignees: The Boeing Company
- Applicants: The Boeing Company
- Inventors: Chad Roderick Adamson; Charley Shin
- Web page: https://patentgrep.com/patent/US11078936B2

## CPC

- F15B 21/0423: Cooling
- B64C 13/36: fluid
- B64C 25/22: fluid
- B64F 5/40: Maintaining or repairing aircraft
- B64F 5/60: Testing or inspecting aircraft components or systems
- B64C 9/00: Adjustable control surfaces or members, e.g. rudders (trimming stabilising surfaces B64C5/10)
- B64D 2033/024: {comprising cooling means}
- B64F 5/00: Designing, manufacturing, assembling, cleaning, maintaining or repairing aircraft, not otherwise provided for; Handling, transporting, testing or inspecting aircraft components, not otherwise provided for
- F15B 1/26: Supply reservoir or sump assemblies
- F15B 2211/20515: Electric motor
- F15B 2211/611: Diverting circuits, e.g. for cooling or filtering
- F15B 2211/62: Cooling or heating means
- F15B 2211/6306: representing a pressure
- F15B 2211/6343: representing a temperature
- F15B 2211/66: Temperature control methods
- F15B 2211/85: Control during special operating conditions
- F15B 2211/857: Monitoring of fluid pressure systems
- F15B: SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- 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
- B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT

## Abstract

An external cooling system for hydraulic fluid of an aircraft hydraulic system. The external cooling system includes a heat exchanger, where an input side of the heat exchanger is connected to a hydraulic fluid reservoir of the aircraft hydraulic system and an output side of the heat exchanger is connected to suction ports of a return side of an electric motor driven pump (EMDP) of the aircraft hydraulic system. The external cooling system operates on 120 VAC power and the hydraulic fluid does not exceed a maximum pressure of 50 pounds per square inch gauge. The EMDP pumps hydraulic fluid through the hydraulic system under conditions wherein fuel tanks in the aircraft are empty, and the external cooling system cools the hydraulic fluid as the EMDP pumps the hydraulic fluid, wherein the hydraulic fluid passes from the hydraulic fluid reservoir and through the external cooling system before entering the EMDP.

## Claims

### Claim 1

A method of cooling hydraulic fluid for an aircraft hydraulic system of an aircraft, the method comprising:
connecting an output side of an external cooling system directly to a return side of an electric motor driven pump through a first hose connection, wherein the electric motor driven pump is a component of the
connecting an input side of the external cooling system directly to a hydraulic fluid reservoir through a second hose connection, wherein the hydraulic fluid reservoir is another component of the aircraft
turning on the external cooling system; and
pumping hydraulic fluid through the aircraft hydraulic system onboard the aircraft with the electric motor driven pump under conditions wherein fuel tanks in the aircraft are empty, wherein the external cooling system cools the hydraulic fluid as the hydraulic fluid passes from the hydraulic fluid reservoir and through the external cooling system before entering the return side the electric motor driven pump.

### Claim 2 (depends on 1)

The method of claim 1, further comprising conducting hydraulic system function tests on the aircraft hydraulic system as the electric motor driven pump pumps the hydraulic fluid through the aircraft hydraulic system and the external cooling system is cooling the hydraulic fluid.

### Claim 3 (depends on 1)

The method of claim 1, wherein the external cooling system comprises a number of air-cooled heat exchangers.

### Claim 4 (depends on 1)

The method of claim 1, further comprising:
monitoring, by a temperature sensor in the external cooling system, a temperature of hydraulic fluid entering the electric motor driven pump;
in response to a determination that the temperature of the hydraulic fluid is below a specified lower threshold, turning off cooling fans in the external cooling system or preventing the cooling fans from turning on; and
in response to a determination that the temperature of the hydraulic fluid exceeds a specified upper threshold, activating an alarm.

### Claim 5 (depends on 4)

The method of claim 4, wherein the specified lower threshold is 15.6° C.

### Claim 6 (depends on 4)

The method of claim 4, wherein the specified upper threshold is 60° C.

### Claim 7 (depends on 1)

The method of claim 1, further comprising:
monitoring, by a pressure sensor in the external cooling system, an air pressure in the hydraulic fluid reservoir; and
activating an alarm if the air pressure is below a specified threshold.

### Claim 8 (depends on 7)

The method of claim 7, wherein the specified threshold is 20 psig.

### Claim 9 (depends on 1)

The method of claim 1, wherein the external cooling system operates on 120 VAC power.

### Claim 10 (depends on 1)

The method of claim 1, wherein the external cooling system operates at a maximum pressure of 50 psig.

### Claim 11

A cooling system comprising:
an aircraft; and
an external cooling system for cooling hydraulic fluid for an aircraft
hydraulic system of the aircraft, the external cooling system comprising:
an output side including a first hose connected to a return side of an electric motor driven pump, wherein the electric motor driven pump is a component of the aircraft hydraulic system of the aircraft;
an input side including a second hose connected to a hydraulic fluid reservoir, wherein the hydraulic fluid reservoir is another component of the aircraft hydraulic system of the aircraft; and
a number of heat exchangers configured to cool hydraulic fluid as the electric motor driven pump pumps the hydraulic fluid through the aircraft hydraulic system under conditions wherein fuel tanks in the aircraft are empty, wherein the hydraulic fluid passes from the hydraulic fluid reservoir and through the external cooling system before entering the electric motor driven pump;
in operation, a path of the hydraulic fluid through the external cooling system includes the first hose, a heat exchanger of the number of heat exchangers, and the second hose without passing through a pump.

### Claim 12 (depends on 11)

The system of claim 11, wherein the external cooling system is configured to cool the hydraulic fluid during hydraulic system function tests on the aircraft hydraulic system of the aircraft.

### Claim 13 (depends on 11)

The system of claim 11, further comprising:
a temperature sensor configured to monitor a temperature of hydraulic fluid entering the electric motor driven pump; and
a controller configured to:
turn off cooling fans in the external cooling system or prevent the cooling fans from turning on if the temperature of the hydraulic fluid is below a specified lower threshold; or
activate an alarm if the temperature of the hydraulic fluid exceeds a specified upper threshold.

### Claim 14 (depends on 13)

The system of claim 13, wherein the specified lower threshold is 15.6° C.

### Claim 15 (depends on 13)

The system of claim 13, wherein the specified upper threshold is 60° C.

### Claim 16 (depends on 11)

The system of claim 11, further comprising:
a pressure sensor configured to monitor air pressure in the hydraulic fluid reservoir; and
a controller configured to activate an alarm if the air pressure is below a specified threshold.

### Claim 17 (depends on 16)

The system of claim 16, wherein the specified threshold is 20 psig.

### Claim 18 (depends on 11)

The system of claim 11, wherein the external cooling system operates on 120 VAC power.

### Claim 19 (depends on 11)

The system of claim 11, wherein the external cooling system operates at a maximum pressure of 50 psig.

### Claim 20

A cooling system comprising:
an aircraft; and
an external cooling system for cooling hydraulic fluid of the aircraft;
the aircraft having an aircraft hydraulic system comprising an
electric motor driven pump and a hydraulic fluid reservoir; the external cooling system comprising:
a number of heat exchangers external of the aircraft;
an input hose connected to the number of heat exchangers and directly connected to the hydraulic fluid reservoir through a first hose connection; and;
an output hose connected to the number of heat exchangers and directly connected to a return side of the electric motor driven pump through a second hose connection;
wherein the number of heat exchangers are configured to cool hydraulic fluid of the aircraft hydraulic system as the electric motor driven pump pumps the hydraulic fluid through the aircraft hydraulic system under conditions wherein fuel tanks in the aircraft are empty, wherein the hydraulic fluid passes from the hydraulic fluid reservoir and through the input hose, the number of heat exchangers, and the output hose before entering the electric motor driven pump, and wherein a path of the hydraulic fluid passes from the hydraulic fluid reservoir and through the input hose, the number of heat exchangers, and the output hose before entering the electric motor driven pump without passing through a pump external to the aircraft.