ISO 8278:2016

DRAFT INTERNATIONAL STANDARD ISO/DIS 8278
ISO/TC 20/SC 10 Secretariat: DIN
Voting begins on Voting terminates on

2013-04-16 2013-07-16
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION  •  МЕЖДУНАРОДНАЯ ОРГАНИЗАЦИЯ ПО СТАНДАРТИЗАЦИИ  •  ORGANISATION INTERNATIONALE DE NORMALISATION

Aerospace — Hydraulic, pressure compensated, variable
delivery pumps — General requirements
Aéronautique et espace — Pompes hydrauliques à débit variable régulé en fonction de la pression —
Exigences générales
[Revision of first edition (ISO 8278:1986)]
ICS 49.080
To expedite distribution, this document is circulated as received from the committee
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©  International Organization for Standardization, 2013

ISO/DIS 8278
©  ISO 2013
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ii © ISO 2013 – All rights reserved

ISO/DIS 8278
Contents Page
Foreword . iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 General requirements . 7
5 Functional requirements . 7
6 Detail design requirements . 19
7 Strength requirements . 21
8 Construction requirements . 23
9 Installation requirements . 25
10 Maintenance requirements . 26
11 Reliability requirements . 26
12 Quality assurance provisions . 27
13 Acceptance tests . 28
14 Qualification tests . 32

ISO/DIS 8278
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 8278 was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 10, Aerospace fluid systems and components.
This second edition cancels and replaces the first edition and also ISO 12334: 2000; the entire document has
been rewritten and it incorporates requirements from ISO 12334.

iv © ISO 2013 – All rights reserved

DRAFT INTERNATIONAL STANDARD ISO/DIS 8278

Aerospace series — Hydraulic, pressure compensated, variable
delivery pumps — General requirements
1 Scope
This International Standard establishes the general requirements for pressure compensated, variable delivery
hydraulic pumps, suitable for use in aircraft hydraulic systems at pressures up to 35 000 kPa (5 000 psi).
This International Standard shall be used in conjunction with detail specifications that is 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 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, Fluid systems — O-rings — Part 1: Inside diameters, cross-sections, tolerances and designation
codes
ISO 6771, Aerospace — Fluid systems and components — Pressure and temperature classifications
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/DIS 8278
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 hydraulic fluids
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
variable delivery, hydraulic pump
self-regulating hydraulic pump that supplies hydraulic power to the hydraulic system (or sub-system) at a
nominal constant pressure
Note 1 to entry: The pump can be driven by a variety of power sources, including:
 by an engine via an accessory gearbox;
 electric motor;
 pneumatic power drive.
3.2
purchaser
organization that has the engineering responsibility for the hydraulic system that includes the pump
Note 1 to entry: Typically, the purchaser is an aircraft manufacturer, an equipment manufacturer that has hydraulic
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
the document compiled by the purchaser 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
manufacturer of the pump who will be responsible for the design, production and qualification of the pump
ISO/DIS 8278
3.5
ports of the hydraulic pump
3.5.1
pump inlet port
port that receives flow from the hydraulic reservoir to supply the pump
3.5.2
pump discharge port
port that supplies pressurised flow to the system
3.5.3
pump case drain port
port that drains internal leakage flow to the reservoir
3.5.4
shaft seal port
port that routes any shaft seal leakage from the pump 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 supply port of the pump
Note 1 to entry: The rated temperature is expressed in degrees centigrade.
3.6.2
minimum continuous temperature
minimum continuous temperature of the fluid to be supplied at the supply port of the pump
Note 1 to entry: The minimum continuous temperature is expressed in degrees centigrade.
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:
 pressure ripple;
 reactions to system functioning;
 demands that may affect fatigue.
3.7.2
inlet pressure
3.7.2.1
rated inlet pressure
minimum pressure measured at the inlet port of the pump at which the pump is required to provide
performance without any degradation, with all other parameters at their rated values, except for the fluid
temperature, which is the minimum continuous temperature
ISO/DIS 8278
3.7.2.2
maximum inlet pressure
maximum steady state inlet pressure at which the pump may be required to operate
3.7.2.3
minimum inlet pressure
lowest pump inlet port pressure, specified by the purchaser, for which the supplier ensures that the pump
might be required to operate without cavitation during a system failure or during a system high-flow transient
condition
Note 1 to entry: 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.
3.7.3
discharge pressure
maximum pressure against which the pump is required to operate continuously at rated temperature, at rated
speed and at zero flow (see Figure 1)
Note 1 to entry: This diagram is given as an indication. It may be presented in a different way, for example, the axes
may be reversed.
Key
1 Actual discharge/pressure characteristic curve
2 At p , q > q
M A N
p pressure
p maximum full-flow pressure (see 3.7.3.1)
M
p rated discharge pressure
N
a
p tolerance range
N
q discharge flow
q actual discharge at maximum full-flow pressure
A
q rated discharge flow (see 3.8)
N
Figure 1 — Delivery/pressure characteristic curve of pumps
ISO/DIS 8278
3.7.3.1
maximum full-flow pressure
maximum discharge pressure at which the pump control will not be acting to reduce pump discharge, at rated
temperature, rated speed, rated inlet and case drain pressure
3.7.3.2
maximum pump discharge transient pressure
peak value of the discharge pressure recorded during a discrete transient event (normally found whilst cycling
from full flow pressure to rated pressure (zero flow))
3.7.3.3
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 to entry: The amplitude of the oscillations is the difference between the average minimum and the average
maximum oscillations recorded during a one-second trace.
3.7.4
case drain pressure
3.7.4.1
maximum case drain pressure
maximum continuous pressure developed by the pump to enable case drain fluid to return to the reservoir
3.7.4.2
rated case drain pressure
nominal pressure at which the pump case is required to operate continuously in the system
3.7.4.3
maximum transient case pressure
maximum pressure peak that may be imposed by the hydraulic system on the pump case drain port
3.8
rated discharge flow
flow rate measured at the pump delivery port under conditions of:
 rated fluid temperature;
 rated inlet pressure;

...