ISO 22181:2021
Aerospace fluid systems and components — Variable displacement hydraulic motors — General specifications
This document establishes the general requirements for variable displacement uni-directional and bi-directional hydraulic motors, suitable for use in aircraft hydraulic systems at pressures up to 35 000 kPa (5 000 psi).
These requirements include:
— design requirements;
— test requirements.
Primary and secondary function motors (see Clause 4) are covered in this document; however, actuators with internal rotation angle limits and low-speed motors are not covered.
This document is intended to be used in conjunction with the detail specification that is particular to each application.
Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 Classification
5 General requirements
5.1 Order of precedence
5.2 Hydraulic system characteristics
5.3 Airworthiness regulations
5.4 Qualification
6 Functional requirements
6.1 Hydraulic fluid
6.2 Pressures
6.2.1 Rated supply pressure
6.2.2 Rated differential pressure
6.2.3 No-load break-out pressure
6.2.4 Motor return port pressure
6.2.5 Case drain pressure
6.3 Flows
6.3.1 Rated consumption
6.3.2 Case drain flow
6.3.3 Shaft seal leakage
6.3.4 External leakage
6.4 Speed and direction of rotation
6.4.1 Speed
6.5 Torque
6.5.1 Rated torque
6.5.2 Break-out torque
6.5.3 Stalling torque
6.5.4 Maximum stalling torque
6.5.5 Torque pulsations
6.6 Variable output load control
6.6.1 General
6.6.2 Response time
6.6.3 Stability
6.7 Motor overall efficiency
6.8 Dynamic characteristics
6.8.1 General
6.8.2 Dynamic braking
6.8.3 Rapid reversals
6.9 Passive operation
6.10 Fluid and ambient temperature
6.10.1 Fluid temperature
6.10.2 Ambient temperature
6.11 Acoustic noise level
6.12 Rated endurance
6.13 Environmental requirements
7 Detail design requirements
7.1 Dimensionally critical components
7.2 Maintainability features
7.3 Seals
7.4 Lubrication
7.5 Balance
7.6 Self-contained failure
7.7 Safety wire sealing
7.8 Electro-conductive bonding
7.9 Marking
7.9.1 Nameplate
7.9.2 Modification standard
7.9.3 Fluid identification
7.9.4 Ports
8 Strength requirements
8.1 General
8.2 Proof pressure
8.2.1 Motor case
8.2.2 Motor inlet port
8.2.3 Motor return port
8.3 Ultimate pressure
8.3.1 Motor case
8.3.2 Motor inlet port
8.3.3 Motor return port
8.4 Pressure impulse (fatigue)
8.5 Port strength
9 Construction requirements
9.1 Materials
9.1.1 General
9.1.2 Metals
9.2 Corrosion protection
9.2.1 General
9.2.2 Ferrous and copper alloys
9.2.3 Aluminium alloys
9.3 Castings
10 Installation requirements
10.1 Dimensions
10.2 Mass
10.3 Mounting
10.4 Orientation
10.5 Drive shaft
10.6 Ports
11 Maintenance requirements
11.1 Maintenance concept
11.2 Service life limitations and storage specifications
12 Reliability requirements
12.1 Equipment compliance
12.2 Requirements
13 Quality assurance provisions
13.1 Responsibility for inspection
13.2 Classification of tests
13.3 Test stand requirements
14 Acceptance tests
14.1 General
14.2 Examination of the product
14.3 Test programme
14.3.1 General
14.3.2 External leakage requirements
14.3.3 Break-in run
14.3.4 Proof pressure and overspeed tests
14.3.5 Operational tests at rated conditions
14.3.6 Break-out torque test
14.3.7 Teardown inspection examination
14.3.8 Run-in
14.3.9 Speed control test
14.3.10 Performance data
14.3.11 Fluid contamination test
14.4 Storage and packaging
15 Qualification procedures
15.1 General
15.2 Qualification procedure
15.2.1 Qualification by analogy
15.2.2 Motor qualification test report
15.2.3 Samples and program of qualification tests
15.3 Qualification testing
15.3.1 Dimensional check
15.3.2 Expanded envelope acceptance tests
15.3.3 Overspeed test
15.3.4 Operational test at overpressure
15.3.5 Calibration
15.3.6 Endurance testing
15.3.7 Environmental tests
15.3.8 Structural tests
15.3.9 Combination tests
15.3.10 Supplementary tests
Bibliography
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Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 Classification
5 General requirements
5.1 Order of precedence
5.2 Hydraulic system characteristics
5.3 Airworthiness regulations
5.4 Qualification
6 Functional requirements
6.1 Hydraulic fluid
6.2 Pressures
6.2.1 Rated supply pressure
6.2.2 Rated differential pressure
6.2.3 No-load break-out pressure
6.2.4 Motor return port pressure
6.2.5 Case drain pressure
6.3 Flows
6.3.1 Rated consumption
6.3.2 Case drain flow
6.3.3 Shaft seal leakage
6.3.4 External leakage
6.4 Speed and direction of rotation
6.4.1 Speed
6.5 Torque
6.5.1 Rated torque
6.5.2 Break-out torque
6.5.3 Stalling torque
6.5.4 Maximum stalling torque
6.5.5 Torque pulsations
6.6 Variable output load control
6.6.1 General
6.6.2 Response time
6.6.3 Stability
6.7 Motor overall efficiency
6.8 Dynamic characteristics
6.8.1 General
6.8.2 Dynamic braking
6.8.3 Rapid reversals
6.9 Passive operation
6.10 Fluid and ambient temperature
6.10.1 Fluid temperature
6.10.2 Ambient temperature
6.11 Acoustic noise level
6.12 Rated endurance
6.13 Environmental requirements
7 Detail design requirements
7.1 Dimensionally critical components
7.2 Maintainability features
7.3 Seals
7.4 Lubrication
7.5 Balance
7.6 Self-contained failure
7.7 Safety wire sealing
7.8 Electro-conductive bonding
7.9 Marking
7.9.1 Nameplate
7.9.2 Modification standard
7.9.3 Fluid identification
7.9.4 Ports
8 Strength requirements
8.1 General
8.2 Proof pressure
8.2.1 Motor case
8.2.2 Motor inlet port
8.2.3 Motor return port
8.3 Ultimate pressure
8.3.1 Motor case
8.3.2 Motor inlet port
8.3.3 Motor return port
8.4 Pressure impulse (fatigue)
8.5 Port strength
9 Construction requirements
9.1 Materials
9.1.1 General
9.1.2 Metals
9.2 Corrosion protection
9.2.1 General
9.2.2 Ferrous and copper alloys
9.2.3 Aluminium alloys
9.3 Castings
10 Installation requirements
10.1 Dimensions
10.2 Mass
10.3 Mounting
10.4 Orientation
10.5 Drive shaft
10.6 Ports
11 Maintenance requirements
11.1 Maintenance concept
11.2 Service life limitations and storage specifications
12 Reliability requirements
12.1 Equipment compliance
12.2 Requirements
13 Quality assurance provisions
13.1 Responsibility for inspection
13.2 Classification of tests
13.3 Test stand requirements
14 Acceptance tests
14.1 General
14.2 Examination of the product
14.3 Test programme
14.3.1 General
14.3.2 External leakage requirements
14.3.3 Break-in run
14.3.4 Proof pressure and overspeed tests
14.3.5 Operational tests at rated conditions
14.3.6 Break-out torque test
14.3.7 Teardown inspection examination
14.3.8 Run-in
14.3.9 Speed control test
14.3.10 Performance data
14.3.11 Fluid contamination test
14.4 Storage and packaging
15 Qualification procedures
15.1 General
15.2 Qualification procedure
15.2.1 Qualification by analogy
15.2.2 Motor qualification test report
15.2.3 Samples and program of qualification tests
15.3 Qualification testing
15.3.1 Dimensional check
15.3.2 Expanded envelope acceptance tests
15.3.3 Overspeed test
15.3.4 Operational test at overpressure
15.3.5 Calibration
15.3.6 Endurance testing
15.3.7 Environmental tests
15.3.8 Structural tests
15.3.9 Combination tests
15.3.10 Supplementary tests
Bibliography