ISO 22089:2009

Aerospace — Hydraulic power transfer units — General specifications

ISO 22089:2009 establishes the general requirements for hydraulic Power Transfer Units (PTUs) ISO 22089:2009 covers uni-directional and bi-directional PTUs. ISO 22089:2009 is used in conjunction with the detail specification particular to each application.

Aéronautique — Unités de transfert de puissance hydraulique — Spécifications générales

General Information

• Status: Published
• Publication Date: 08-Feb-2009
• ICS: 49.080 - Aerospace fluid systems and components
• Technical Committee: ISO/TC 20/SC 10 - Aerospace fluid systems and components
• Drafting Committee: ISO/TC 20/SC 10/WG 9 - Hydraulic power and actuation equipment
• Current Stage: 9093 - International Standard confirmed
• Completion Date: 06-Nov-2020

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 22089
First edition
2009-02-15

Aerospace — Hydraulic power transfer
units — General specifications
Aéronautique — Unités de transfert de puissance hydraulique —
Spécifications générales




Reference number
ISO 22089:2009(E)
©
ISO 2009

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ISO 22089:2009(E)
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ISO 22089:2009(E)
Contents Page
Foreword. v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Classification. 8
5 General requirements. 9
5.1 General. 9
5.2 Hydraulic system characteristics. 9
5.3 Airworthiness requirements . 10
5.4 Qualification . 10
6 Functional requirements. 10
6.1 Hydraulic fluid . 10
6.2 PTU pump/motor displacement. 10
6.3 PTU pressure. 11
6.4 PTU pump pressure. 12
6.5 Motor pressure. 14
6.6 Case drain pressures . 14
6.7 Flows. 14
6.8 Leakage. 15
6.9 Speed and direction of rotation. 16
6.10 Efficiency . 18
6.11 Control . 18
6.12 Rated temperature . 21
6.13 Acoustic noise level . 21
6.14 Endurance . 21
6.15 Environmental requirements . 22
7 Detail design requirements. 22
7.1 Dimensionally critical components . 22
7.2 Maintainability features. 22
7.3 Seals. 23
7.4 Lubrication . 23
7.5 Balance . 23
7.6 System separation/rip-stop . 23
7.7 Drive shaft . 23
7.8 Self-contained failure . 23
7.9 Safety wire sealing. 23
7.10 Electro-conductive bonding . 23
7.11 Marking . 24
8 Strength requirements . 24
8.1 Pressure loads . 24
8.2 Proof pressures . 24
8.3 Burst pressure . 25
8.4 Pressure impulse (fatigue). 26
8.5 Pressure and structural load . 26
8.6 Port strength . 26
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ISO 22089:2009(E)
9 Construction. 26
9.1 Materials. 26
9.2 Corrosion protection . 27
9.3 Castings . 28
10 Installation requirements . 28
10.1 Dimensions. 28
10.2 Mass . 28
10.3 Mounting . 28
10.4 Ports . 28
11 Maintenance. 28
11.1 Maintenance concept. 28
11.2 Service life limitations and storage specifications. 28
12 Reliability . 29
12.1 Equipment compliance. 29
12.2 Requirements . 29
13 Quality assurance provisions. 29
13.1 Responsibility for inspection. 29
13.2 Classification of tests . 29
13.3 Test stand requirements . 29
14 Acceptance tests. 30
14.1 General . 30
14.2 Examination of the product. 30
14.3 Test programme and inspection methods . 30
15 Qualification tests . 35
15.1 Purpose . 35
15.2 Qualification procedure. 35

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ISO 22089:2009(E)
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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 22089 was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 10, Aerospace fluid systems and components.

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ISO 22089:2009(E)
Introduction
Hydraulic power transfer units (PTUs) are designed to transfer hydraulic power, but not hydraulic fluid,
between two independent hydraulic systems, or between hydraulic sub-systems.
This International Standard establishes the general requirements for PTUs, including:
⎯ design requirements;
⎯ test requirements.

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INTERNATIONAL STANDARD ISO 22089:2009(E)

Aerospace — Hydraulic power transfer units — General
specifications
1 Scope
This International Standard establishes the general requirements for hydraulic Power Transfer Units (PTUs).
This International Standard covers uni-directional and bi-directional PTUs.
This International Standard is used in conjunction with the detail specification particular to each application.
2 Normative references
The following referenced documents are indispensable for the application of this document. 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 3323, Aircraft — Hydraulic components — Marking to indicate fluid for which component is approved
ISO 3601-1, 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 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
ISO 11218, Aerospace — Cleanliness classification for aeronautical fluids
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ISO 22089:2009(E)
3 Terms and definitions
For the purposes of this document the terms and definitions given in ISO 8625-1, ISO 8625-2 and ISO 8625-3
and the following apply.
3.1
Power Transfer Unit (PTU)
hydraulic device that is able to transfer hydraulic power between two independent hydraulic systems (or sub-
systems) without transferring hydraulic fluid
NOTE The PTU generally consists of two rotating groups, housed separately and connected by a driveshaft.
Hydraulic energy supplied to the hydraulic motor from one system drives the pump, providing hydraulic power to the other
system.
3.2
uni-directional PTU
hydraulic pump that transfers hydraulic power between two independent hydraulic systems (or sub-systems),
in one direction only, such that the pump and motor cannot reverse their functions
3.3
bi-directional PTU
hydraulic pump that transfers hydraulic power between two independent hydraulic systems (or sub-systems)
in either direction
NOTE The PTU acts to provide hydraulic power to the system that is experiencing the greater power demand using
hydraulic power from the other (lower demand) system. The pump and motor can reverse their functions such that the
pump can function as a motor and vice-versa, depending on the direction of operation.
3.4
purchaser
organization that has the engineering responsibility for the hydraulic system that includes the PTU and who
approves the supplier for the design, development and manufacture of aerospace PTUs
NOTE Typically, the purchaser is an aircraft manufacturer, an equipment manufacturer that has hydraulic system
responsibility or a modification centre. The purchaser is responsible for the compilation of the detail specification.
3.5
detail specification
document 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.
3.6
supplier
manufacturer of the PTU, responsible for the design, production and qualification of the PTU
3.7
ports of the uni-directional PTU
3.7.1
pump case drain port
(if included) port that drains internal leakage flow to the reservoir
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ISO 22089:2009(E)
3.7.2
pump inlet port
port that receives flow from the hydraulic reservoir to supply the pump
3.7.3
pump discharge port
port that supplies pressurized flow to the system
3.7.4
motor case drain port
(if included) port that drains motor internal leakage flow to the reservoir
3.7.5
motor supply port
port that receives flow from the hydraulic system to power the motor
3.7.6
motor return port
port that returns flow to the reservoir
3.7.7
shaft seal port
port that routes any shaft seal leakage from the PTU to an overboard drain, collector tank, etc.
3.8
ports of the bi-directional PTU
3.8.1
case drain port
(if included) port that drains internal leakage flow to the reservoir
3.8.2
HP port
port that receives flow from the hydraulic system to power the motor, or supplies pressurized flow to the
system
NOTE When the PTU half is acting as a pump, the HP port supplies pressurized flow to the system. When the PTU
half is acting as a motor, the HP port receives flow from the hydraulic system.
3.8.3
LP port
port that returns flow to the reservoir or flow from the hydraulic reservoir to supply the pump
NOTE When the PTU half is acting as a pump, the LP port receives flow from the hydraulic reservoir. When the PTU
half is acting as a motor, the LP port returns flow to the reservoir.
3.8.4
shaft seal port
port that routes any shaft seal leakage from the PTU to an overboard drain, collector tank, etc.
3.9
design operating pressure
normal maximum steady pressure
NOTE Excluded are reasonable tolerances, transient pressure effects such as may arise from:
⎯ pressure ripple;
⎯ reactions to system functioning;
⎯ demands that may affect fatigue.
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ISO 22089:2009(E)
3.10
break-out pressure
minimum difference between the pump and motor differential pressures at which the PTU motor will start
operating under conditions specified in the detail specification
NOTE Typically, the PTU will not act to provide power until a threshold breakout differential pressure between
systems (or sub-systems) has been exceeded.
3.11
rated case-drain pressure
nominal pressure at which the PTU pump and motor cases are required to operate continuously in the system
3.12
maximum transient case pressure
maximum pressure peak that can be imposed by the hydraulic system on the pump or motor case drain port
3.13
maximum transient discharge pressure
pressure recorded during a discrete transient event [normally found whilst cycling from full-flow pressure to
rated pressure (zero flow)]
3.14
maximum pump case drain pressure
maximum continuous pressure developed by the PTU pump to enable case drain fluid to return to the
reservoir
3.15
maximum inlet pressure
maximum steady state inlet pressure at which the PTU pump might be required to operate during a system
failure or during a system high-flow transient condition
3.16
minimum inlet pressure
lowest inlet pressure, specified by the purchaser, for which the supplier ensures that the PTU pump might be
required to operate without cavitation during a system failure or during a system high-flow transient condition
NOTE For the purposes of this International Standard, cavitation is assumed to occur when there is a 2 % reduction
in discharge flow with reducing inlet pressure.
3.17
rated inlet pressure
minimum pressure measured at the inlet port of the PTU pump at which the PTU is required to provide the
performance without any degradation, with all the other parameters at their rated values, except for the fluid
temperature, which is the minimum continuous temperature
3.18
maximum full-flow pressure for category C PTUs
maximum discharge pressure at which the pump control will not be acting to reduce pump delivery flow, at
rated temperature, rated motor supply and return pressures, pump rated inlet and case drain pressure
NOTE Maximum full-flow pressure is not applicable to categories A and B PTUs.
3.19
rated discharge pressure for categories A and B PTUs
minimum discharge pressure that is met with rated motor differential pressure applied, at the minimum steady
state discharge flow just prior to stall and with all other parameters at rated conditions
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ISO 22089:2009(E)
3.20
rated discharge pressure (or stall pressure) for category C PTUs
nominal pressure that the PTU pump is required to maintain at rated temperature, rated inlet pressure, rated
case drain pressure and at zero discharge flow when the PTU is operated continuously with rated motor
differential pressure
3.21
pressure pulsations
oscillations of the pump discharge pressure, occurring during nominally steady operating conditions, at a
frequency equal to the number of pistons times the drive shaft speed, or a multiple thereof
NOTE 1 The amplitude of the oscillations is the difference between the average minimum and the average maximum
oscillations recorded during a one-second trace.
NOTE 2 This is a characteristic of the PTU and the system operating together, not solely a PTU characteristic.
3.22
rated motor return pressure
rated return pressure of the system that is supplying the PTU
3.23
rated motor supply pressure
rated pressure of the system that is supplying the PTU
3.24
maximum motor case drain pressure
pressure developed in the PTU motor when the maximum system return pressure is applied to the PTU motor
case drain port
3.25
maximum motor supply transient pressure
peak value of the PTU motor supply pressure during the operation of the PTU
3.26
no-load break-out pressure
minimum motor differential pressure required to initiate and sustain rotation of the PTU at zero pump
differential pressure with all pump ports at the rated inlet pressure
3.27
rated differential pressure
differential pressure, measured between the PTU motor supply and return ports, required to produce the PTU
pump maximum full-flow pressure when the motor is at the rated supply pressure
3.28
stall pressure
minimum opposing differential pressure which stops the rotation of the PTU drive shaft, or reduces the speed
to that required to maintain PTU internal leakage, with the pressure at the PTU motor supply port at its rated
and the motor operating return and rated case drain pressures
NOTE Some PTUs have a built-in bypass flow (also known as an idle circuit) to ensure that the pump/motor never
stops rotating when it is selected to run.
3.29
rated temperature
maximum continuous temperature of the fluid to be supplied at the supply port of the PTU motor and the inlet
port of the PTU pump expressed in degrees centigrade
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ISO 22089:2009(E)
3.30
rated discharge flow
flow rate measured at the PTU pump discharge port under conditions of:
⎯ rated temperature;
⎯ rated motor supply flow rate;
⎯ rated inlet pressure;
⎯ rated case drain pressure;
⎯ maximum full-flow pressure;
⎯ using the hydraulic fluid specified in the detail specification
NOTE The flow is measured in the compressed state.
3.31
rated supply flow
flow rate measured at the PTU motor supply port under conditions of:
⎯ rated temperature;
⎯ rated pump discharge flow rate;
⎯ motor operating differential pressure;
⎯ rated case drain pressure;
⎯ maximum full-flow pressure (category C PTU only);
⎯ using the hydraulic fluid specified in the detail specification
NOTE The flow shall be measured in the expanded state.
3.32
rated displacement
maximum theoretical volume of fluid generated by one revolution of the PTU pump drive shaft and/or as the
maximum theoretical volume of fluid consumed by one revolution of the PTU motor drive shaft expressed in
millilitres per revolution
3.33
volumetric efficiency
ratio of the PTU pump output flow to the PTU motor input flow when the PTU is operating at rated conditions
or any other operating conditions if so specified in the detail specification
NOTE It is derived from the following equation:
PTU volumetric efficiency (%) = [(Q × D )/(Q × D )] × 100
p m m p
where
Q is the PTU pump discharge flow in litres per minute;
p
Q is the PTU motor supply flow in litres per minute;
m
D is the PTU pump rated displacement in millilitres per revolution;
p
D is the PTU motor rated displacement in millilitres per revolution.
m
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ISO 22089:2009(E)
3.34
overall efficiency
ratio of the PTU pump output fluid power to the PTU motor input fluid power when the PTU is operating at
rated conditions or any other operating conditions if so specified in the detail specification
NOTE It is derived from the following equation:
PTU overall efficiency (%) = [(∆P × Q )/(∆P × Q )] × 100
p p m m
where
∆P is the differential pressure between the PTU pump discharge and inlet ports in kilopascals;
p
∆P is the differential pressure between the PTU motor supply and return ports in kilopascals;
m
Q is the PTU pump discharge flow in litres per minute;
p
Q is the PTU motor supply flow in litres per minute.
m
3.35
maximum no-load speed
rotational speed reached by the PTU pump and motor with the motor operating at rated conditions (rated fluid
temperature and motor supply flow) and with the PTU pump delivering fluid in a system that is unpressurized
3.36
rated speed
speed at which the PTU will operate continuously at the rated motor flow, at rated temperature and at rated
motor differential pressure expressed as a number of revolutions of the PTU drive shaft per minute
3.37
response time
time interval between the moment when an increase (or decrease) of the PTU pump discharge pressure
begins and the subsequent time when the discharge pressure reaches its first maximum (or minimum) value,
when connected to a specified circuit
NOTE This is only applicable to category C PTUs, and the response time will be different if the PTU is operating
continuously or intermittently.
3.38
stability
freedom from persistent or quasi-persistent oscillation or “hunting” of the PTU (cycl
...