EN 60706-3:2006

SLOVENSKI STANDARD
01-januar-2007
Vzdrževalnost opreme - 3. del: Overjanje, zbiranje, analiza in predstavitev
podatkov (IEC 60706-3:2006)
Maintainability of equipment -- Part 3: Verification and collection, analysis and
presentation of data
Instandhaltbarkeit von Geräten -- Teil 3: Verifizierung und Erfassung, Analyse und
Darstellung von Daten
Maintenabilité de matériel -- Partie 3: Vérification et recueil, analyse et présentation de
données
Ta slovenski standard je istoveten z: EN 60706-3:2006
ICS:
03.100.40 Raziskave in razvoj Research and development
21.020 =QDþLOQRVWLLQQDþUWRYDQMH Characteristics and design of
VWURMHYDSDUDWRYRSUHPH machines, apparatus,
equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 60706-3
NORME EUROPÉENNE
July 2006
EUROPÄISCHE NORM
ICS 03.120.01; 21.020
English version
Maintainability of equipment
Part 3: Verification and collection, analysis and
presentation of data
(IEC 60706-3:2006)
Maintenabilité de matériel  Instandhaltbarkeit von Geräten
Partie 3: Vérification et recueil, Teil 3: Verifizierung und Erfassung,
analyse et présentation de données Analyse und Darstellung von Daten
(CEI 60706-3:2006) (IEC 60706-3:2006)

This European Standard was approved by CENELEC on 2006-07-01. CENELEC members are bound to comply
with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and notified
to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, the Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2006 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60706-3:2006 E
Foreword
The text of document 56/1094/FDIS, future edition 2 of IEC 60706-3, prepared by IEC TC 56,
Dependability, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as
EN 60706-3 on 2006-07-01.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2007-04-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2009-07-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 60706-3:2006 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:
IEC 60300-1 NOTE  Harmonized as EN 60300-1:2003 (not modified).
IEC 60300-2 NOTE  Harmonized as EN 60300-2:2004 (not modified).
IEC 60300-3 NOTE  Harmonized as EN 60300-3 (series) (not modified).
__________
- 3 - EN 60706-3:2006
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

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.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.
Publication Year Title EN/HD Year

IEC 60050-191 1990 International Electrotechnical Vocabulary - -
(IEV)
Chapter 191: Dependability and quality of
service
1)
IEC 60300-3-5 - Dependability management - -
Part 3-5: Application guide - Reliability test
conditions and statistical test principles

IEC 60300-3-10 2001 Dependability management - -
Part 3-10: Application guide - Maintainability

1) 2)
IEC 60300-3-12 - Dependability management EN 60300-3-12 2004
Part 3-12: Application guide - Integrated
logistic support
1) 2)
IEC 60300-3-14 - Dependability management EN 60300-3-14 2004
Part 3-14: Application guide - Maintenance
and maintenance support
1) 2)
IEC 60706-2 - Maintainability of equipment EN 60706-2 2006
Part 2: Maintainability requirements and
studies during the design and development
phase
1) 2)
IEC 61160 - Design review EN 61160 2005

1)
IEC 61649 - Goodness-of-fit tests, confidence intervals - -
and lower confidence limits for Weibull
distributed data
1)
IEC 61710 - Power law model - Goodness-of-fit tests and - -
estimation methods
1)
Undated reference.
2)
Valid edition at date of issue.

NORME CEI
INTERNATIONALE
IEC
60706-3
INTERNATIONAL
Deuxième édition
STANDARD
Second edition
2006-04
Maintenabilité de matériel –
Partie 3:
Vérification et recueil, analyse
et présentation de données
Maintainability of equipment –
Part 3:
Verification and collection, analysis
and presentation of data
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électronique ou mécanique, y compris la photocopie et les photocopying and microfilm, without permission in writing from
microfilms, sans l'accord écrit de l'éditeur. the publisher.
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МеждународнаяЭлектротехническаяКомиссия
Pour prix, voir catalogue en vigueur
For price, see current catalogue

60706-3  IEC:2006 – 3 –
CONTENTS
FOREWORD.7
INTRODUCTION.11
1 Scope.13
2 Normative references .13
3 Terms and definitions .15
4 Introduction to maintainability verification .15
4.1 Objective of verification .15
4.2 Maintenance support concepts influencing maintainability verification .17
4.3 Methods of verification .17
4.4 Verification process.17
4.5 Conditions and constraints .19
4.6 Qualitative and quantitative verification procedures.21
5 Procedures for verification of qualitative maintainability.23
5.1 Design review.23
5.2 Review of test experience .23
5.3 Ease-of-maintenance studies .25
5.4 Review of maintenance task analysis .25
5.5 Review of operational experience.25
6 Procedures for verification of quantitative maintainability.27
6.1 Maintainability predictions .27
6.2 Verification based on demonstration tests .27
6.3 Verification based on field data .27
7 Demonstration procedures.29
7.1 General .29
7.2 Demonstration process.29
7.3 Demonstration planning.29
7.4 Conditions and constraints .31
7.5 Demonstration after modification .31
8 Elements of the verification procedure.33
8.1 Utilization of data sources .33
8.2 Data acquisition and analysis .33
8.3 Evaluation .35
8.4 Comparison.37
9 Collection, analysis and presentation of maintainability data.37
9.1 General .37
9.2 Maintenance concept .37
9.3 Data sources .39
9.4 Item demonstration and field data.41
9.5 Analysis procedures .41
9.6 Data presentation.43

Annex A (normative) Maintainability demonstration procedures.49
Annex B (normative) Maintainability demonstration test methods .55
Annex C (normative) Analysis of maintainability related data .71

60706-3  IEC:2006 – 5 –
Bibliography.75

Figure B.1 – Test method 8: Sequential test plan .34

Table 1 – Qualitative and quantitative maintainability verification procedures.23
Table 2 – Active repair task data summary form.47
Table 3 – Active repair time summary form .47
Table 4 – Preventive maintenance summary .47
Table A.1 – Test methods .49
Table B.1 – Test method 7: Acceptance and rejection numbers .67
Table B.2 – Sampling plans for specified p , p , α, β (p < 0,2) .69
0 1 0
Table C.1 – Critical values of d .73

60706-3  IEC:2006 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MAINTAINABILITY OF EQUIPMENT –

Part 3: Verification and collection, analysis
and presentation of data
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60706-3 has been prepared by IEC technical committee 56:
Dependability.
This second edition cancels and replaces the first edition, published in 1983, and constitutes
a technical revision.
The major technical changes with regard to the first edition concern combining the original
Sections 6 and 7 from the first edition and adding the two statistical annexes from IEC 60706-6,
which have been included as Annexes B and C.

60706-3  IEC:2006 – 9 –
The text of this standard is based on the following documents:
FDIS Report on voting
56/1094/FDIS 56/1109/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
IEC 60706 consists of the following parts , under the general title Maintainability of
equipment:
NOTE Each part outlines the application of specific techniques to implement a maintainability programme.
Part 1: Introduction, requirements and maintenance programme
Part 2: Maintainability studies during the design phase
Part 3: Verification and collection, analysis and presentation of data
Part 4: Guide to maintenance and maintenance support planning
Part 5: Diagnostic testing
Part 6: Statistical methods in maintainability evaluation
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
___________
1 Parts 1, 4 and 6 are currently being absorbed into other parts of IEC 60706. The Foreword of the relevant part

will give an explanatory text.

60706-3  IEC:2006 – 11 –
INTRODUCTION
The design of an item includes the need for efficient maintenance techniques to ensure that
the item continues to operate properly. Before it is put into service it is necessary to verify
that the proposed maintenance procedures can be executed as designed and the collection
and analysis of data is an essential part of the verification process.
The data used for verification may come from a variety of sources and what is used in
particular circumstances will depend on many factors, including what historical data are
available and the status of the design. For verification that maintainability targets have been
met, it is preferable to conduct tests that generate data on the product under review.
Historical data have to be sorted for relevance to the project and when useful data have been
selected, they are analysed to provide the information required.
There are a number of verification procedures that are explained in this standard with the
associated analysis techniques. They are designed to check the adequacy of the maintenance
procedures, the tools and equipment supplied for maintenance, the adequacy of the technical
publications and the ease of maintenance of the item. This enables improvements to be made
to the maintenance procedures and, if necessary, modifications to be carried out on the item
to improve maintainability. It is important to include any required changes to the design of the
item as early as possible, if possible before the start of production, in order to minimize costs.
This initial analysis is, in most cases, a statistical analysis based on a small sample of data. It
is therefore preferable that the collection and analysis of data should go on after the item
enters service so that the results achieved by the verification process are refined and
improved. These data are important to determine the adequacy of the maintenance support,
as this is not so easy to assess in an initial verification analysis.
IEC 60706-3 forms part of a hierarchy of standards dealing with dependability, as described
below.
IEC 60300-1 and IEC 60300-2 are the IEC top-level standards that provide guidance on how
to incorporate dependability, incorporating reliability, availability and maintainability, into
manufactured products. The top-level standard on maintainability is the application guide for
maintainability, IEC 60300-3-10, which forms part of the IEC 60300-3 series of standards. It
can be used to implement a maintainability programme covering the initiation, development
and in-service phases of a product, which form part of the tasks described in IEC 60300-2. It
also provides guidance on how the maintenance aspects of the tasks should be considered in
order to achieve optimum maintainability.

60706-3  IEC:2006 – 13 –
MAINTAINABILITY OF EQUIPMENT –

Part 3: Verification and collection, analysis
and presentation of data
1 Scope
This part of IEC 60706 describes the various aspects of verification necessary to ensure that
the specified maintainability requirements of an item have been met and provides suitable
procedures and test methods. While maintainability verification as such should be a
mandatory part of any maintainability programme (see IEC 60300-3-10), each individual case
requires appropriate methods to be carefully selected in order to ensure overall cost-
effectiveness.
This standard also addresses the collection, analysis and presentation of maintainability
related data, which may be required during, and at the completion of, design and during item
production and operation.
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.
IEC 60050(191):1990, International Electrotechnical Vocabulary (IEV) – Chapter 191:
Dependability and quality of service
IEC 60300-3-5, Dependability management – Part 3-5: Application guide – Reliability test
conditions and statistical test principles
IEC 60300-3-10:2001, Dependability management – Part 3-10: Application guide –
Maintainability
IEC 60300-3-12, Dependability management – Part 3-12: Application guide – Integrated
logistic support
IEC 60300-3-14, Dependability management – Part 3-14: Application guide – Maintenance
and maintenance support
IEC 60706-2, Maintainability of equipment – Part 2 – Section Five: Maintainability studies
during the design phase
IEC 61160, Design review
IEC 61649, Goodness-of-fit tests, confidence intervals and lower confidence limits for Weibull
distributed data
IEC 61710, Power law model – Goodness-of-fit tests and estimation methods
___________
2 To be published.
60706-3  IEC:2006 – 15 –
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050(191),
together with the following definitions, apply.
3.1
customer selected equipment
portion of the item under consideration which has been specially selected by the customer
NOTE Generally the supplier has no control over the maintainability of this portion, but it should be considered in
the design of the item. Cooperation between customer and supplier is clearly desirable.
3.2
maintainability demonstration
activity performed on individual items or samples to indicate achievement of a specific
maintainability requirement and/or to generate maintainability data
3.3
maintainability verification
monitoring actions, inspections or both for the purpose of determining compliance by the
contractor with the maintainability requirements specified for an item
3.4
maintenance concept
interrelationship between the maintenance echelons, the indenture levels and the levels of
maintenance to be applied for the maintenance of an item
3.5
maintenance policy
general approach to the provision of maintenance and maintenance support based on the
objectives and policies of owners, users and customers
3.6
software support centre
centralized software maintenance service
4 Introduction to maintainability verification
4.1 Objective of verification
The objective is to verify that both qualitative and quantitative maintainability requirements
have been met within the specified performance limitations. This includes verification that the
defined maintenance activity has restored the item to the specified performance level. The
verification is applicable to hardware, software and maintenance facilities.
Maintainability verification is a process of assessing the results of maintainability experience.
This assessment can begin as soon as data and results are available and may continue
throughout the project and extend into field use.
This is further expanded with respect to
– qualitative maintainability requirements, see Clause 5,
– quantitative maintainability requirements, see Clause 6.
Demonstration procedures are described in Clause 7.

60706-3  IEC:2006 – 17 –
4.2 Maintenance support concepts influencing maintainability verification
When performing maintainability verification, it should be borne in mind that the following
maintenance support elements have a decisive influence on the effectiveness of the
maintenance process:
– maintenance facilities;
– support equipment;
– material support;
– maintenance personnel and training;
– technical documentation and manuals;
– transportation, handling and storage conditions.
IEC 60300-3-14 contains further details on maintenance support.
4.3 Methods of verification
Maintainability verification is a continuous process of generating, collecting, analysing and
evaluating maintainability related data as they become available in the course of project
development, and comparing results with specified maintainability requirements.
Methods of maintainability verification differ according to the programme phase, as follows:
a) analysis and review. This includes analysis of historical data, comparisons with the results
of design reviews and maintainability predictions. This may include analysis of field data
later in the life cycle;
b) special studies. Conducted during the concept and definition or design and development
phases to investigate general or detailed problems. Examples include ease-of-
maintenance studies, maintenance task analysis and simulation studies;
c) demonstration tests. Performed at the end of the design and development phase on
prototype or early production items, if the analytical means or special studies do not give
sufficient evidence as to whether maintainability conforms to specified requirements.
d) review of operational experience. Verification may be left to operational experience and
review of field data, correlated, if appropriate, with the review and analysis of historical
data;
e) spatial imaging simulation. Three-dimensional computer simulations of maintenance
actions may be performed at appropriate times throughout the design process to verify
that the proposed sequence of actions, access and other workspace considerations
support the achievement of the required level of maintainability.
4.4 Verification process
The procedural elements of the verification process are as follows:
a) identification and activation of possible sources of data
in the early project phases, only historical data of comparable previous items can be used.
Later, design, manufacturing, test and finally field data become available. Maintainability
demonstrations in this context provide a special data source for the generation of
maintainability data under simulated conditions;

60706-3  IEC:2006 – 19 –
b) acquisition and analysis of data
data collection, review and screening to ensure their applicability;
c) evaluation
processing of data using mathematical models or checklists to obtain quantitative
characteristics or qualitative properties of maintainability;
d) comparison with requirements
the results of the evaluation are compared with specified maintainability characteristics
and properties to check whether maintainability requirements are met;
In addition, the following information is necessary for a complete maintainability verification.
e) item maintenance plan
the item maintenance plan is the application of the maintenance concept to that item and
should be defined for the interpretation of both historical data and data from other
sources. The maintenance plan also defines conditions and constraints on maintenance
and support to be considered in the process of maintainability verification;
f) reliability data
relevant reliability indices, such as the expected frequency of maintenance actions, may
be required for the calculation of some maintainability indices from estimated or observed
times for single maintenance actions. Reliability data will also affect aspects of verification
such as establishing priorities, thus giving prerequisites for evaluation. If this information
is not available or is incomplete, assumptions should be stated. The quality of available
information and the assumptions made will affect the relevancy of verification results.
4.5 Conditions and constraints
Methods should be specified by the customer or selected by the contractor and described in
the maintainability programme plan (as detailed in IEC 60706-2). The following should be
considered in deciding between alternative verification procedures related to each
maintainability requirement.
a) resources available
if a budget limit is contractually specified, this will influence the selection of verification
methods. Possible future usability of verification facilities should be taken into account;
b) acceptance criteria
The acceptance criteria for each specified maintainability requirement should be
considered in a trade-off against cost and time requirements;
c) time constraints
The choice between verification methods may be restricted by requirements affecting the
timely availability of results. The procedure should be structured in accordance with the
overall development programme schedule;
d) spatial imaging simulation
This may be used if test samples and support equipment are not available when needed;

60706-3  IEC:2006 – 21 –
e) availability of test samples and/or support equipment
especially when maintainability demonstration tests are to be conducted, it should be
ensured that the test schedule is in agreement with the overall programme schedule, and
that the test samples and the support equipment required are readily available during the
time period envisaged for the test;
f) skill level and experience of maintainability analysts
maintainability verification, based on design reviews or analysis, calls for highly qualified
and experienced personnel to analyse drawings and plans;
g) risk of wrong decisions
These should be assessed with regard to the item's complexity and the quality and amount
of historical data;
h) special support requirements
the necessary checkout equipment, facilities, personnel qualification, etc. need to be
available at the appropriate time in the schedule;
i) influence of environmental conditions or assumptions
Any deviation from the operational environment in terms of maintenance/checkout
equipment, facilities, spares, personnel skill level, etc. should be particularly assessed;
j) data collection
the requirements concerning the collection of representative maintainability data during
test and operation should be clearly identified. This includes formats, codes and data
processing;
k) customer-contractor relationship
any monitoring, rejection or control authority assumed by the customer should be clearly
defined;
l) maintainability warranties and guarantees
Contractual consequences of not meeting maintainability requirements or acceptance
criteria should be specified, for example, in terms of penalties or loss of incentives;
m) realism of verification
The maintainability verification should include realistic representation of the operational
environment and maintenance technicians that are representative of those that would be
expected in the operational environment.
4.6 Qualitative and quantitative verification procedures
The maintainability verification process is directed towards providing adequate and timely
information concerning the degree of achievement of maintainability requirements. Since
these requirements may be expressed in qualitative or in quantitative form, the maintainability
verification procedure shall be designed accordingly, using one of the following methods of
verification or a combination of them:
– analysis and review;
– design studies, tests and spatial imaging simulation;
– demonstration by testing or during operational use.
Both qualitative and quantitative aspects of maintainability verification can be covered by an
appropriate choice of methods, as indicated in Table 1.

60706-3  IEC:2006 – 23 –
Table 1 – Qualitative and quantitative maintainability verification procedures
Analysis Design During
Type of procedure and studies and Demonstration operational
review tests use
Qualitative verification Design review X
procedures
Review of test
X X X
experience
Ease-of-
maintenance X
studies
Review of
maintenance task X X
analysis
Review of
operational  X
experience
Spatial imaging
X X
simulation
Quantitative Maintainability
X X
verification prediction
procedures
Verification based
X X
on test data
Verification based
X
on field data
5 Procedures for verification of qualitative maintainability
5.1 Design review
Qualitative maintainability can be verified during the general product design review by
evaluating design documentation against a set of design requirements and engineering
standards (see IEC 61160).
Depending on the nature of the project, a checklist addressing specific maintainability
features should be used as a guideline.
This type of investigation requires good engineering assessment of maintainability character-
istics of a design and should be based on previous experience. It can be applied in the design
stage as part of normal engineering practice for step-by-step design improvement. For
maintainability verification purposes, design review is generally used only in combination with
some other method.
5.2 Review of test experience
Data from operational use are usually unavailable or too late for timely maintainability
verification. However, such data might be gained in earlier project stages in development
trials or by special demonstration tests in a realistic, simulated environment. To be
representative and reproducible, the test conditions should be clearly defined. Any deviations
from reality should be assessed. The main discrepancies can be discovered when alternative
approaches are still possible.

60706-3  IEC:2006 – 25 –
5.3 Ease-of-maintenance studies
Quick answers to typical maintainability questions may be offered by ease-of-maintenance
studies directed towards the solution of special problems. Should a mock-up or 3D-CAD of the
item be available, these problems can be investigated directly. In some cases a virtual mock-
up can be used (three dimensional (3D) computer modelling). Clearer information is then
gained for maintainability verification purposes, for example on
– clearances for use of maintenance tools,
– accessibility where maintenance is needed,
– duration of different tasks under different conditions,
– available work space,
– feasibility of simultaneous maintenance work by different team members,
physical complexity of maintenance tasks;
– feasibility of the demonstration goal, requirement or objective;
– safety precautions concerning high voltages or high temperatures.
5.4 Review of maintenance task analysis
Maintenance task analysis is concerned with the resources needed to accomplish
maintenance. Typically, it forms part of the maintenance planning process which precedes
operational deployment. Maintenance task analysis is an essential part of the integrated
logistic support procedure described in IEC 60300-3-12 and is also discussed in
IEC 60300-3-14.
A review of the maintenance task analysis may be used for qualitative verification.
5.5 Review of operational experience
An assessment of the qualitative maintainability of an item can be achieved by observing its
behaviour during operation. The following are questions of specific interest in this context:
a) Adequacy of the pre-defined maintenance and support concept
Are there any unforeseen difficulties from the operational environment?
Has there been any excessive consumption of spares?
b) Suitability of tools and test equipment
Are sufficient test points provided for check-out purposes?
Are any additional tools or test equipment necessary?
c) Personnel skill level required to perform maintenance actions
Are maintenance problems induced by inadequate training or by human engineering
aspects?
Is the skill level required appropriate?
d) Feasibility of maintenance actions
Are established checkout procedures adequate for failure diagnosis and isolation?
Are replaceable units properly accessible?
e) Adequacy of technical manuals
Are the maintenance instructions comprehensive and understandable?

60706-3  IEC:2006 – 27 –
f) Software aspects of maintainability
Have software elements required in the maintenance process been adequately
considered, for example, with respect to testing, training and technical manuals?
g) Safety precautions
Is there any possibility of a hazardous situation during maintenance actions?
This information on the operational practices and problems allows for a realistic assessment
of qualitative maintainability properties. However, it requires a long period for establishing and
reviewing observations.
6 Procedures for verification of quantitative maintainability
6.1 Maintainability predictions
Maintainability predictions can be performed either for the complete item or at lower indenture
levels. A prediction may be accepted as a verification where design risk is small or where the
customer considers that sufficient evidence of compliance has been obtained during
development.
Maintainability prediction is described in IEC 60706-2.
6.2 Verification based on demonstration tests
Maintenance data can be obtained in a relatively short time from limited maintainability
demonstration tests in a simulated environment, using a prototype, mock-up or a 3D
simulation program. This is one way of contractually verifying compliance. In this case, data
collection should be simple since it is integrated into the overall test procedure and is part of
the working routines of the test personnel.
However, results should be reviewed for any deviations from operational data due to
inadequate environmental simulation. Where possible, significant differences should be offset
by the use of application factors.
See Clause 7 for details of maintainability demonstration.
6.3 Verification based on field data
Maintenance data collected during the operational use of an item represent the optimum
source of information on the quantitative maintainability characteristics. To enable proper
conclusions to be drawn from these data, they should include, as a minimum:
– identification of the item, assembly, subassembly, etc;
– reason for the maintenance action;
– type of maintenance action performed; this may be either scheduled maintenance (e.g.
servicing, inspection, calibration, overhaul, renewal of parts) or unscheduled maintenance
(e.g. repair on site, removal and replacement, shop repair);
– man-hours for maintenance action;
– elapsed time for maintenance action;
– total maintenance downtime (active maintenance downtime, maintenance delay time);

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– operational hours for each item;
– number and skill level of maintenance team;
– utilization of test/check-out equipment;
– maintenance access;
– spares and material consumption.
Statistical evaluation of these data over a sufficient time period may yield a realistic basis for
quantitative maintainability verification. Field data form an instructive source of information for
use in later projects. They could then serve as a reliable historical database for maintainability
verification.
However, this procedure can be applied only in the operational phase. It is time consuming
and requires an efficient data collection system. The results are therefore available only late
in the development programme.
7 Demonstration procedures
7.1 General
Maintainability demonstrations are only one aspect of the overall maintainability verification
process. However, demonstration results are often the only contractual basis for a
maintainability verification before delivery of the item. The essentials of the demonstration
procedure are therefore summarized below.
7.2 Demonstration process
Steps in the maintainability demonstration may include the following:
a) feasibility testing
tests are usually performed on mock-ups, engineering models or using three-dimensional
simulation programs during the development of an item. The purpose is to generate
information on ease-of-maintenance, installation and maintenance and repair times;
b) design testing
tests, for example, concurrent with preliminary design reviews, but not officially used for
qualification and usually not monitored by customer's representatives. Results are
documented and may serve to improve confidence in maintainability estimates. Design
testing may be performed on prototypes or production items;
c) formal demonstration
formal demonstration may be part of official qualification and should be performed on pre-
production or production items. It is performed according to mutually approved conditions
and monitored by the customer's representatives.
7.3 Demonstration planning
A test and demonstration plan should form a part of the maintainability programme plan. It
should be the basic planning document for all formal maintainability tests and should include
the following:
a) a list of demonstration tasks with costs, including software elements, selected according
to the following criteria:
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– preventive maintenance. Representative tasks should be selected from the planned
operational use of the item.
– corrective maintenance. Tasks should be selected to cover a representative
percentage of the total predicted rep
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