ISO 9206:2016

INTERNATIONAL ISO
STANDARD 9206
Second edition
2016-03-01
Aerospace series — Constant
displacement hydraulic motors —
General specifications
Série aérospatiale — Moteurs hydrauliques à cylindrée fixe —
Spécifications générales
Reference number
©
ISO 2016
© ISO 2016, Published in Switzerland
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ii © ISO 2016 – All rights reserved

Contents Page
Foreword .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Classification . 6
5 General requirements . 6
5.1 Order of precedence . 6
5.2 Hydraulic system characteristics . 6
5.3 Airworthiness regulations . 6
5.4 Qualification . 6
6 Functional requirements . 7
6.1 Hydraulic fluid . 7
6.2 Pressures . 7
6.2.1 Rated supply pressure. 7
6.2.2 Rated differential pressure . 7
6.2.3 No-load break-out pressure . 7
6.2.4 Motor return port pressure . 7
6.2.5 Case port pressure . . 7
6.3 Flows . 8
6.3.1 Rated consumption . 8
6.3.2 Case drain flow . 8
6.3.3 Shaft seal leakage flow . 8
6.3.4 External leakage . 8
6.4 Speed and direction of rotation . 9
6.4.1 Speed . 9
6.5 Torque . 9
6.5.1 Rated torque . 9
6.5.2 Break-out torque . 9
6.5.3 Stalling torque . 9
6.5.4 Torque pulsations . 9
6.6 Motor overall efficiency .11
6.7 Dynamic characteristics .12
6.7.1 General.12
6.7.2 Dynamic braking .12
6.7.3 Rapid reversals .12
6.8 Passive operation .12
6.9 Rated temperature .12
6.10 Acoustic noise level .12
6.11 Rated endurance .12
6.12 Environmental requirements .13
7 Detail design requirements .13
7.1 Dimensionally critical components .13
7.2 Maintainability features .13
7.3 Seals .14
7.4 Lubrication .14
7.5 Balance .14
7.6 Self-contained failure .14
7.7 Safety wire sealing .14
7.8 Electro-conductive bonding .14
7.9 Marking .14
7.9.1 Nameplate .14
7.9.2 Fluid identification .15
7.9.3 Ports .15
8 Strength requirements .15
8.1 General .15
8.2 Proof pressure .15
8.2.1 Motor case .15
8.2.2 Motor inlet port .15
8.2.3 Motor return port .15
8.3 Ultimate pressure .16
8.3.1 Motor case .16
8.3.2 Motor inlet port .16
8.3.3 Motor return port .16
8.4 Pressure impulse (fatigue) .16
8.5 Port strength .16
9 Construction requirements .16
9.1 Materials .16
9.1.1 General.16
9.1.2 Metals .17
9.2 Corrosion protection .17
9.2.1 General.17
9.2.2 Ferrous and copper alloys .17
9.2.3 Aluminium alloys .18
9.3 Castings .18
10 Installation requirements.18
10.1 Dimensions .18
10.2 Mass .18
10.3 Mounting .18
10.4 Orientation .19
10.5 Drive shaft .19
10.6 Ports .19
11 Maintenance requirements .19
11.1 Maintenance concept .19
11.2 Service life limitations and storage specifications .19
12 Reliability requirements .20
12.1 Equipment compliance .20
12.2 Requirements .20
13 Quality assurance provisions .20
13.1 Responsibility for inspection .20
13.2 Classification of tests .20
13.3 Test stand requirements .20
14 Acceptance tests .21
14.1 General .21
14.2 Examination of the product .21
14.3 Test programme .21
14.3.1 General.21
14.3.2 External leakage requirements .22
14.3.3 Break-in run .22
14.3.4 Proof pressure and overspeed tests .22
14.3.5 Operational tests at rated conditions .22
14.3.6 Break-out torque test .23
14.3.7 Teardown inspection examination .23
14.3.8 Run-in .23
14.3.9 Performance data .23
14.3.10 Fluid contamination test .24
14.3.11 Electro-conductive bonding .25
14.4 Storage and packaging .25
iv © ISO 2016 – All rights reserved

15 Qualification procedures .25
15.1 General .25
15.2 Qualification procedure .25
15.2.1 Qualification by analogy .25
15.2.2 Motor qualification test report .25
15.2.3 Samples and program of qualification tests .25
15.3 Qualification testing .26
15.3.1 Dimensional check .26
15.3.2 Expanded envelope acceptance tests .26
15.3.3 Overspeed test .27
15.3.4 Operational test at overpressure .27
15.3.5 Calibration .27
15.3.6 Endurance testing .28
15.3.7 Environmental tests .31
15.3.8 Structural tests .32
15.3.9 Supplementary tests .33
Bibliography .34
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 10, Aerospace fluid systems and components.
This second edition cancels and replaces the first edition (ISO 9206:1990) and ISO 12333:2000. The
entire document has been rewritten and it incorporates requirements from ISO 12333:2000.
vi © ISO 2016 – All rights reserved

INTERNATIONAL STANDARD ISO 9206:2016(E)
Aerospace series — Constant displacement hydraulic
motors — General specifications
1 Scope
This International Standard establishes the general requirements for constant displacement hydraulic
motors, suitable for use in aircraft hydraulic systems at pressures up to 35 000 kPa (5 000 psi).
Primary and secondary function motors (see Clause 4) are covered in this International Standard;
however, actuators with internal rotation angle limits and low-speed motors are not covered.
This International Standard is to be used in conjunction with the detail specification that is particular
to each application.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 2093, Electroplated coatings of tin — Specification and test methods
ISO 2669, Environmental tests for aircraft equipment — Steady-state acceleration
ISO 2671, Environmental tests for aircraft equipment — Part 3.4 : Acoustic vibration
ISO 2685, Aircraft — Environmental test procedure for airborne equipment — Resistance to fire in
designated fire zones
ISO 3323, Aircraft — Hydraulic components — Marking to indicate fluid for which component is approved
ISO 3601-1:2012, Fluid power systems — O-rings — Part 1: Inside diameters, cross-sections, tolerances and
designation codes
ISO 7137, Aircraft — Environmental conditions and test procedures for airborne equipment
ISO 7320, Aerospace — Couplings, threaded and sealed, for fluid systems — Dimensions
ISO 8078, Aerospace process — Anodic treatment of aluminium alloys — Sulfuric acid process, undyed coating
ISO 8079, Aerospace process — Anodic treatment of aluminium alloys — Sulfuric acid process, dyed coating
ISO 8081, Aerospace process — Chemical conversion coating for aluminium alloys — General purpose
ISO 8399-1, Aerospace — Accessory drives and mounting flanges (Metric series) — Part 1: Design criteria
ISO 8399-2, Aerospace — Accessory drives and mounting flanges (Metric series) — Part 2: Dimensions
ISO 8625-1, Aerospace — Fluid systems — Vocabulary — Part 1: General terms and definitions related to
pressure
ISO 8625-2, Aerospace — Fluid systems — Vocabulary — Part 2: General terms and definitions relating to
flow
ISO 8625-3, Aerospace — Fluid systems — Vocabulary — Part 3: General terms and definitions relating to
temperature
1)
ISO 11218:— , Aerospace — Cleanliness classification for hydraulic fluids
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 8625-1, ISO 8625-2, ISO 8625-3,
and the following apply.
3.1
fixed displacement hydraulic motor
mechanical actuator that converts hydraulic pressure and flow into torque and angular displacement
(rotation)
3.2
purchaser
organization that has the engineering responsibility for the hydraulic system that includes the motor
Note 1 to entry: Typically, the purchaser is an aircraft manufacturer, an equipment manufacturer that has the
actuation system responsibility or a modification centre.
Note 2 to entry: The purchaser is responsible for the compilation of the detail specification.
3.3
detail specification
document compiled by the purchaser (3.2) that specifies the following:
a) technical requirements;
b) acceptance and qualification test requirements;
c) reliability requirements;
d) quality requirements;
e) packaging requirements;
f) other requirements
3.4
supplier
organization that provides the motor
Note 1 to entry: Typically, the supplier is the manufacturer of the motor who will be responsible for the design,
production, and qualification of the motor
3.5
ports of the hydraulic motor
3.5.1
motor inlet port
port that receives flow from the hydraulic system to supply the motor
3.5.2
motor return port
port that returns flow back to the system
3.5.3
motor case drain port
port that drains internal leakage flow to the reservoir
1) To be published. (Revision of ISO 11218:1993)
2 © ISO 2016 – All rights reserved

3.5.4
shaft seal port
port that routes any shaft seal leakage from the motor to an overboard drain, collector tank, etc.
3.6
temperature terms
3.6.1
rated temperature
maximum continuous temperature of the fluid to be supplied at the inlet port of the motor
Note 1 to entry: It is expressed in degrees centigrade.
3.6.2
minimum continuous temperature
minimum temperature of the fluid to be continuously supplied at the supply port of the motor
Note 1 to entry: It is expressed in degrees centigrade.
Note 2 to entry: This temperature is generally higher than the survival temperature.
3.7
pressure terms
3.7.1
design operating pressure
normal maximum steady pressure
Note 1 to entry: Excluded are reasonable tolerances, transient pressure effects such as may arise from the
following:
— pressure ripple;
— reactions to system functioning;
— demands that may affect fatigue.
3.7.2
rated supply pressure
system rated pressure, which is normally the hydraulic power generation system design operating
pressure (3.7.1)
3.7.3
rated differential pressure
differential pressure measured between the motor inlet and outlet ports required to produce rated
torque (3.11.1)
3.7.4
no-load break-out pressure
differential pressure required for starting the output shaft, without interruption, with the case drain
port at the rated return pressure
3.7.5
motor return pressure
3.7.5.1
nominal motor return pressure
pressure generated at the return port as the motor returns flow back to the system
3.7.5.2
rated motor return pressure
maximum pressure at the return port
Note 1 to entry: This is applicable to uni-directional motors only.
Note 2 to entry: This is a stressing term only as the nominal motor pressure is generally considerably less than
the rated motor return pressure.
3.7.6
case drain pressure
3.7.6.1
rated case drain pressure
nominal pressure at which the motor case is required to operate continuously in the system
3.7.6.2
maximum case pressure
maximum of either
— the maximum pressure peak that may be imposed by the hydraulic system on the motor case drain
port (3.5.3), or
— the pressure resulting from integral bypassing of the rated flow towards the outlet and drain ports
in order to take into account the accidental transitory separation of the components
3.8
rated consumption
flow rate measured at the motor inlet port (3.5.1) under conditions of the following:
— rated fluid temperature;
— rated differential pressure (3.7.3);
— rated speed (3.10.1);
— using the hydraulic fluid specified in the detail specification (3.3)
3.9
rated displacement
maximum theoretical volume of fluid generated by one revolution of its output shaft
Note 1 to entry: It shall be expressed in cubic centimetres per revolution (cubic inches per revolution).
Note 2 to entry: The rated displacement shall be calculated from the geometrical configuration of the motor,
without allowing for the effects of the following:
— permissible manufacturing tolerances;
— distortions of the motor structure;
— the compressibility of the hydraulic fluid;
— internal leakage;
— temperature.
Note 3 to entry: The rated displacement is used to indicate the size of the motor rather than its performance.

4 © ISO 2016 – All rights reserved

3.10
speed terms
3.10.1
rated speed
maximum speed at which the motor is required to operate continuously at rated temperature (3.6.1)
and at rated differential pressure (3.7.3)
Note 1 to entry: The rated speed shall be expressed as the number of revolutions of the motor output shaft
per minute.
3.10.2
maximum no-load speed
speed reached at rated conditions with no opposing torque
3.11
torque terms
3.11.1
rated torque
minimum torque value at rated operating conditions
3.11.2
break-out torque
minimum torque against which the motor will start at operating conditions specified in the detail
specification (3.3)
Note 1 to entry: The specification shall be met at any angular position of the output shaft.
3.11.3
stalling torque
minimum opposing torque which stops the rotation of the outlet shaft at the rated supply pressure (3.7.2)
and for the outlet port and case drain port pressures specified in the detail specification (3.3)
3.12
motor overall efficiency
obtained from the formula:
motor overall efficiency (%) = (output shaft power/input fluid power) × 100
where
output shaft power= shaft torque × RPM;
input fluid power= (inlet pressure – return pressure) × rated flow
Note 1 to entry: This formula ignores compressibility effects. If this formula is to be used, the flow rate
measurement should be made on the compressed flow stream.
3.13
rated endurance
total number of hours and cycles of operation to be included in the endurance phase of its
qualification testing
3.14
first article inspection
process that conducts the following:
— verifies that the parts of a component comply with the drawings;
— verifies that the manufacturing processes have been compiled and are adhered to;
— verifies that the assembly processes have been compiled and are adhered to;
— verifies that the acceptance test of the component is in accordance with the test procedure, and that
the results of the test are in agreement with the test requirements
4 Classification
The hydraulic motors covered by this International Standard are classified in two categories.
— Category A: Primary function motors, for example, flight controls, slats, flaps, adjustable planes,
transfer units, constant speed drives, etc.
— Category B: Secondary function motors, for example, hoists, guns, radars, doors, etc.
The motor category shall be specified in the detail specification.
5 General requirements
5.1 Order of precedence
The detail specification shall take precedence in the case of a conflict between the requirements of this
International Standard and the detail specification.
5.2 Hydraulic system characteristics
The hydraulic motor shall be designed to be operated by the hydraulic system as defined in the detail
specification.
The detail specification shall include the characteristics of the hydraulic system in which the motor
is to be used. This shall include the flow versus pressure curves for the supply, return, and case drain
lines for the following hydraulic fluid temperatures:
— normal operating temperature (for example, +20 °C);
— rated temperature;
— minimum continuous temperature.
5.3 Airworthiness regulations
The hydraulic motor shall comply with the applicable airworthiness regulations.
5.4 Qualification
Hydraulic motors furnished under this International Standard shall be products that have passed the
qualification tests that are specified in the detail specification.
6 © ISO 2016 – All rights reserved

6 Functional requirements
6.1 Hydraulic fluid
The detail specification shall state the applicable hydraulic fluid.
6.2 Pressures
6.2.1 Rated supply pressure
The value of the rated supply pressure shall be stated in the detail specification and shall be one of the
following values of rated supply pressures listed in Table 1 (derived from ISO 6771).
Table 1 — Rated supply pressure
Pressure Metric system Imperial system
Class kPa basic psi basic
A 4 000 600
B 10 500 1 500
C 16 000 2 500
D 21 000 3 000
E 28 000 4 000
J 35 000 5 000
6.2.2 Rated differential pressure
The rated differential pressure shall be specified in the detail specification.
6.2.3 No-load break-out pressure
The no-load break-out pressure shall be specified in the detail specification.
6.2.4 Motor return port pressure
6.2.4.1 Nominal return pressure
The nominal return pressure shall be specified in the detail specification.
6.2.4.2 Rated motor return pressure
The rated motor return pressure (where applicable) shall also be specified in the detail specification.
Unless otherwise specified in the detail specification, the rated motor return pressure shall be
7 000 kPa (1 000 psi).
6.2.5 Case port pressure
6.2.5.1 Rated case port pressure
The rated case port pressure shall be specified in the detail specification.
Caution should be taken defining the rated case pressure. Too high a pressure may cause abnormal
shaft seal and shaft bearing loading, affecting their operation and reducing the motor life.
6.2.5.2 Maximum case port pressure
The maximum case drain port pressure shall be specified in the detail specification.
6.3 Flows
6.3.1 Rated consumption
The detail specification shall state the value of the rated consumption, which shall be in l/min (or gpm).
6.3.2 Case drain flow
The detail specification shall state that the motor shall be capable of producing at least a minimum case
drain flow.
The motor case flow rate [which shall be in l/min (or gpm)] shall be specified under the following
conditions:
1) the motor turning at rated torque and speed;
2) the motor turning at zero torque;
3) the motor stalled, shaft locked at any position.
The minimum and maximum case drain flow shall be stated at conditions specified in the detail
specification.
6.3.3 Shaft seal leakage flow
The detail specification shall state the value of the maximum dynamic shaft seal leakage (which shall
be in drops/min) at the following conditions:
a) New build:
— the motor filled with fluid, but un-pressurized;
— when subject to proof pressure at ambient temperature;
— when the motor is operating at rated consumption flow.
b) Qualification testing:
— over the expanded test envelope;
— at the completion of the endurance test;
— when subject to proof pressure at rated temperature;
— when subject to ultimate pressure at rated temperature.
6.3.4 External leakage
No leakage sufficient to form a drop from the motor case or from any case static seal shall be permitted.
Dynamic shaft seal leakage shall not be considered as external leakage.
8 © ISO 2016 – All rights reserved

6.4 Speed and direction of rotation
6.4.1 Speed
6.4.1.1 Rated speed
The rated speed of the motor shall be specified in the detail specification.
NOTE As an indication, the maximum recommended values are given in the Nomograph in Figures 1 and
2. If speeds are kept well below those indicated by the curves, the operating life may be improved. However,
several system factors such as fluid, temperature, duty cycle, contamination, expected life, etc. will also
influence the values.
6.4.1.2 Overspeed
Unless otherwise specified in the detail specification, the motor shall be capable of operating without
any failures at 125 % of rated motor discharge flow for the durations and at the conditions of Table 6
and/or Table 7 for 30 minutes.
6.4.1.3 Maximum no-load speed
The maximum no-load speed shall be specified in the detail specification.
6.4.1.4 Direction of rotation
Unless otherwise specified in the detail specification, the hydraulic motor shall operate satisfactorily in
either direction of rotation. It shall not be necessary to alter the motor to effect a change in the direction
of rotation; it should only be necessary to reverse the direction of flow.
NOTE For single direction of rotation applications, an improvement of weight and efficiency may be obtained
by optimizing the timing design parameters for the intended direction of rotation.
6.5 Torque
6.5.1 Rated torque
The rated torque shall be specified in the detail specification.
6.5.2 Break-out torque
The break-out torque shall be specified in the detail specification.
6.5.3 Stalling torque
The stalling torque shall be specified in the detail specification.
At low speeds (500 to 800 rpm), the mechanical efficiency of hydraulic motors can be up to 99 %.
This high efficiency should be considered when stressing the mechanisms that are powered by the
hydraulic motor.
6.5.4 Torque pulsations
The motor shall be designed to deliver continuous torque without excessive amplitude ripple
(considered as being over ±10 % of rated torque) when the motor is operated within the rated speed
range at any of the conditions specified in Clause 15.
Y 175 225 275 325 375
150 200 250 300 350400
l/min.
a
35 000 kPa
a
28 000 kPa
a
21 000 kPa
X
Key
Y rated motor displacement in millilitres per revolution
X motor speed in rpm × 1 000
a
Recommended maximum rated speeds.
Figure 1 — Nomograph of maximum recommended values for rated speeds against motor
displacement (Metric units)
10 © ISO 2016 – All rights reserved
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