Programmes for reliability growth

Specifies requirements and gives guidelines for the exposure and removal of weaknesses in hardware and software items for the purpose of reliability growth. Applies when the product specification calls for a reliability growth programme of equipment (electronic, electromechanical and mechanical hardware as well as software) or when it is known that the design is unlikely to meet the requirements without improvement. The main changes with respect to the previous edition are listed below. A subclause on planning reliability growth in the design phase has been added. A subclause on management aspects covering both reliability growth in design and the test phase has been added. A clause on reliability growth in the field has been added.

Programme für das Zuverlässigkeitswachstum

Programmes de croissance de fiabilité

Spécifie des exigences et fournit des directives de détection et l'élimination des fragilités du matériel et du logiciel dans le but d'accroître la fiabilité. S'applique quand la spécification du produit demande un programme de croissance de fiabilité de l'équipement (matériel électronique, électromécanique et mécanique, ainsi que logiciel) ou quand on sait que la conception est peu susceptible de répondre aux exigences sans amélioration préalable. Les changements majeurs par rapport à l'édition précédente sont les suivants: Un paragraphe sur la planification de croissance de fiabilité pendant la phase de conception a été ajouté. Un paragraphe sur l'organisation couvrant à la fois la croissance de fiabilité dans la conception et la phase d'essai a été ajouté. Un article sur la croissance de fiabilité en exploitation a été ajouté.

Programi za rast zanesljivosti (IEC 61014:2003)

General Information

Status
Published
Publication Date
18-Sep-2003
Technical Committee
Drafting Committee
Parallel Committee
Current Stage
6060 - Document made available
Due Date
19-Sep-2003
Completion Date
19-Sep-2003

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SLOVENSKI SIST EN 61014:2004
STANDARD
september 2004
Programi za rast zanesljivosti (IEC 61014:2003)
Programmes for reliability growth (IEC 61014:2003)
ICS 03.100.40; 21.020 Referenčna številka
SIST EN 61014:2004(en)

© Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

---------------------- Page: 1 ----------------------
EUROPEAN STANDARD EN 61014
NORME EUROPÉENNE
EUROPÄISCHE NORM September 2003
ICS 03.100.40; 03.120.01; 21.020
English version
Programmes for reliability growth
(IEC 61014:2003)
Programmes de croissance de fiabilité Programme für das
(CEI 61014:2003) Zuverlässigkeitswachstum
(IEC 61014:2003)

This European Standard was approved by CENELEC on 2003-09-01. 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, Czech Republic,

Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Lithuania, Luxembourg, Malta,

Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and 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

© 2003 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 61014:2003 E
---------------------- Page: 2 ----------------------
EN 61014:2003 - 2 -
Foreword

The text of document 56/859/FDIS, future edition 2 of IEC 61014, prepared by IEC TC 56,

Dependability, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as

EN 61014 on 2003-09-01.
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) 2004-06-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2006-09-01
Annexes designated "normative" are part of the body of the standard.
In this standard, annex ZA is normative.
Annex ZA has been added by CENELEC.
__________
Endorsement notice

The text of the International Standard IEC 61014:2003 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 61703 NOTE Harmonized as EN 61703:2002 (not modified).
ISO 9000 NOTE Harmonized as EN ISO 9000:2000 (not modified).
ISO 9001 NOTE Harmonized as EN ISO 9001:2000 (not modified).
__________
---------------------- Page: 3 ----------------------
- 3 - EN 61014:2003
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

This European Standard incorporates by dated or undated reference, provisions from other

publications. These normative references are cited at the appropriate places in the text and the

publications are listed hereafter. For dated references, subsequent amendments to or revisions of any

of these publications apply to this European Standard only when incorporated in it by amendment or

revision. For undated references the latest edition of the publication referred to applies (including

amendments).

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
1) 2)
IEC 60300-1 Dependability management EN 60300-1
- 2003
Part 1: Dependability management
systems
1) 2)
IEC 60300-2 - Part 2: Dependability programme EN 60300-2 1996
elements and tasks
IEC 60300-3-1 - Part 3-1: Application guide - Analysis - -
techniques for dependability - Guide on
methodology
IEC 60300-3-5 2001 Part 3-5: Application guide - Reliability - -
test conditions and statistical test
principles
IEC 60605-2 - Equipment reliability testing - - -
Part 2: Design of test cycles
IEC 60605-3 Series Equipment reliability testing - - -
Part 3: Preferred test conditions
IEC 60605-4 - Part 4: Statistical procedures for - -
exponential distribution - Point
estimates, confidence intervals,
prediction intervals and tolerance
intervals
1) 2)
IEC 60812 - Analysis techniques for system HD 485 S1 1987
reliability - Procedure for failure mode
and effects analysis (FMEA)
1) 2)
IEC 61025 - Fault tree analysis (FTA) HD 617 S1 1992
IEC 61160 - Formal design review - -
Undated reference.
Valid edition at date of issue.
---------------------- Page: 4 ----------------------
EN 61014:2003 - 4 -
Publication Year Title EN/HD Year
_ 1)
IEC 61164 Reliability growth - Statistical test and - -
estimation methods
---------------------- Page: 5 ----------------------
NORME CEI
INTERNATIONALE IEC
61014
INTERNATIONAL
Deuxième édition
STANDARD
Second edition
2003-07
Programmes de croissance de fiabilité
Programmes for reliability growth
 IEC 2003 Droits de reproduction réservés  Copyright - all rights reserved

Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in any

utilisée sous quelque forme que ce soit et par aucun procédé, form or by any means, electronic or mechanical, including

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.

International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland

Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch Web: www.iec.ch

CODE PRIX
Commission Electrotechnique Internationale PRICE CODE
International Electrotechnical Commission
Международная Электротехническая Комиссия
Pour prix, voir catalogue en vigueur
For price, see current catalogue
---------------------- Page: 6 ----------------------
61014  IEC:2003 – 3 –
CONTENTS

FOREWORD .......................................................................................................................... 7

INTRODUCTION ...................................................................................................................11

1 Scope .............................................................................................................................13

2 Normative references......................................................................................................13

3 Terms and definitions .....................................................................................................15

4 Basic concepts ...............................................................................................................27

4.1 General .................................................................................................................27

4.2 Origins of weaknesses and failures........................................................................27

4.2.1 General......................................................................................................27

4.2.2 Systematic weaknesses .............................................................................29

4.2.3 Residual weaknesses ................................................................................29

4.3 Basic concepts for reliability growth in product development process;

integrated reliability engineering concept ...............................................................31

4.4 Basic concepts for reliability growth in the test phase ............................................31

4.5 Planning of the reliability growth and estimation of achieved reliability during

the design phase ...................................................................................................35

4.5.1 General......................................................................................................35

4.5.2 Reliability growth in the product development/design phase.......................35

4.5.3 Reliability growth with the test programmes ...............................................37

5 Management aspects......................................................................................................41

5.1 General .................................................................................................................41

5.2 Procedures including processes in the design phase .............................................43

5.3 Liaison...................................................................................................................43

5.4 Manpower and costs for design phase ...................................................................47

5.5 Cost benefit ...........................................................................................................47

6 Planning and execution of reliability growth programmes ................................................49

6.1 Integrated reliability growth concepts and overview ...............................................49

6.2 Reliability growth activities in the design phase .....................................................51

6.2.1 Activities in concept and product requirements phase ................................51

6.2.2 Product definition and preliminary design...................................................53

6.2.3 Project design phase .................................................................................53

6.2.4 Tooling, first production runs (preproduction), production phase ................57

6.2.5 Product fielded phase ................................................................................57

6.3 Reliability growth activities in the validation test phase ..........................................57

6.4 Considerations for reliability growth testing............................................................59

6.4.1 General......................................................................................................59

6.4.2 Test planning .............................................................................................59

6.4.3 Special considerations for non-repaired or one-shot (expendable)

items and components ...............................................................................63

6.4.4 Classification of failures.............................................................................65

6.4.5 Classes of non-relevant failures.................................................................65

6.4.6 Classes of relevant failures........................................................................67

6.4.7 Categories of relevant failures that occur in test ........................................67

6.4.8 Process of reliability improvement in reliability growth tests .......................69

---------------------- Page: 7 ----------------------
61014  IEC:2003 – 5 –

6.4.9 Mathematical modelling of test reliability growth ........................................73

6.4.10 Nature and objectives of modelling ............................................................73

6.4.11 Concepts of reliability measures in reliability growth testing as used

in modelling ...............................................................................................75

6.4.12 Reporting on reliability growth testing and documentation..........................81

7 Reliability growth in the field ...........................................................................................85

Bibliography..........................................................................................................................87

Figure 1 – Comparison between growth and repair processes in reliability growth testing .....33

Figure 2 – Planned improvement (reduction) of the equivalent failure rate.............................37

Figure 3 – Planned reliability improvement expressed in terms of probability of survival........37

Figure 4 – Patterns of relevant test or field failures with time ................................................39

Figure 5 – Overall structure of a reliability growth programme...............................................43

Figure 6 – Chart showing liaison links and functions .............................................................47

Figure 7 – Integrated reliability engineering process .............................................................51

Figure 8 – Process of reliability growth in testing...................................................................71

Figure 9 – Characteristic curve showing instantaneous and extrapolated failure intensities ...77

Figure 10 – Projected failure intensity estimated by modelling...............................................79

Figure 11 – Examples of growth curves and “jumps” .............................................................81

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61014  IEC:2003 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PROGRAMMES FOR RELIABILITY GROWTH
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, 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 61014 has been prepared by IEC technical committee 56:

Dependability.
The text of this standard is based on the following documents:
FDIS Report on voting
56/859/FDIS 56/863/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.

This second edition of IEC 61014 cancels and replaces the first edition, published in 1989,

and constitutes a technical revision.
---------------------- Page: 9 ----------------------
61014  IEC:2003 – 9 –
The main changes with respect to the previous edition are listed below.
• References to dependability management standards have been inserted.

• Terms and definitions related to the reliability growth during the product design have been

added.

• Flow diagrams for reliability growth in 4.4 and 6.4.8 (see Figures 1 and 8) have been

corrected.

• A subclause on planning reliability growth in the design phase has been added (see 4.5).

• A subclause on management aspects covering both reliability growth in design and the

test phase has been added (see Clause 5).

• Clause 6 has been extended to include reliability growth in the design phase with its

analytical and test aspects.

• The figure showing projected failure intensity estimated by modelling (see Figure 10) has

been corrected.
• A clause on reliability growth in the field (see Clause 7) has been added.

The committee has decided that the contents of this publication will remain unchanged until 2011.

At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
---------------------- Page: 10 ----------------------
61014  IEC:2003 – 11 –
INTRODUCTION

Reliability improvement by a growth programme should be part of an overall reliability activity

in the development of a product. This is especially true for a design that uses novel or

unproven techniques, components, or a substantial content of software. In such a case the

programme may expose, over a period of time, many types of weaknesses having design-

related causes. It is essential to reduce the probability of failure due to these weaknesses to

the greatest extent possible to prevent their later appearance in formal tests or in the field.

At that late stage, design correction is often highly inconvenient, costly and time-consuming.

Life-cycle costs can be minimized if the necessary design changes are made at the earliest

possible stage.

IEC 60300-3-5, Clause 1 refers to a “reliability growth (or improvement) programme” employ-

ing equipment reliability design analysis and reliability testing, with the principal objective to

realize reliability growth. Reliability design analysis applies analytical methods and techniques

described in IEC 60300-3-1. Reliability design analysis is of a particular value, as it allows

early identification of potential design weakness, well before design completion. This allows

introduction of design modifications that are inexpensive and relatively easy to implement

without consequences such as major design changes, programme delays, modification of

tooling and manufacturing processes. The reliability growth testing and environmental

arrangements for the test part of this programme are essentially the same as those covered

by IEC 60300-3-5, IEC 60605-2 and IEC 60605-3.

The importance of the reliability growth programme, integrated into the design or product

development process, and known as integrated reliability engineering, is driven by limited

time to market, programme costs and striving for product cost reduction.

Although effective for disclosure of potential field problems, a reliability growth testing pro-

gramme alone is typically expensive, requiring extensive test time and resources, and the

corrective actions are considerably more costly than if they were found and corrected in the

early stages of design. Additionally, the duration of these tests, sometimes lasting for a very

long time, would seriously affect the marketing or deployment schedule of the system.

The cost-effective solution to these challenges is a reliability growth programme fully

integrated in both the design and evaluation phase as well as the testing phase. This effort is

enabled by strong project management, by design engineering and often by customer

participation and involvement. Over the past few years, leading industry organizations have

developed and applied analytical and test methods fully integrated with the design efforts for

increasing the reliability during the product design phase. This reduces reliance on formal and

lengthy reliability growth testing. This technology is the basis for the integrated reliability

growth strategy in this standard and will be discussed further in Clause 6. Some definitions

and concepts are given first in order to lay the groundwork for discussing the integrated

reliability growth methodologies.
---------------------- Page: 11 ----------------------
61014  IEC:2003 – 13 –
PROGRAMMES FOR RELIABILITY GROWTH
1 Scope

This International Standard specifies requirements and gives guidelines for the exposure and

removal of weaknesses in hardware and software items for the purpose of reliability growth.

It applies when the product specification calls for a reliability growth programme of equipment

(electronic, electromechanical and mechanical hardware as well as software) or when it is

known that the design is unlikely to meet the requirements without improvement.

A statement of the basic concepts is followed by descriptions of the management, planning,

testing (laboratory or field), failure analysis and corrective techniques required. Mathematical

modelling, to estimate the level of reliability achieved, is outlined briefly.
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 60300-1, Dependability management – Part 1: Dependability management systems

IEC 60300-2, Dependability management – Part 2: Guidance for dependability programme

management

IEC 60300-3-1, Dependability management – Part 3-1: Application guide – Analysis tech-

niques for dependability – Guide on methodology

IEC 60300-3-5:2001, Dependability management – Part 3-5: Application guide – Reliability

test conditions and statistical test principles
IEC 60605-2, Equipment reliability testing – Part 2: Design of test cycles

IEC 60605-3 (all parts), Equipment reliability testing – Part 3: Preferred test conditions

IEC 60605-4, Equipment reliability testing – Part 4: Statistical procedures for exponential

distribution – Point estimates, confidence intervals, prediction intervals and tolerance intervals

IEC 60812, Analysis techniques for system reliability – Procedure for failure mode and effects

analysis (FMEA)
IEC 61025, Fault tree analysis (FTA)
IEC 61160, Formal design review
IEC 61164, Reliability growth – Statistical test and estimation methods
___________
Second edition to be published.
Second edition to be published.
---------------------- Page: 12 ----------------------
61014  IEC:2003 – 15 –
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

NOTE 1 Certain terms come from IEC 60050(191) and, where this is the case, the concept from that publication is

referenced in square brackets after the definition. ISO 9000:2000 is used as referenced to quality vocabulary.

NOTE 2 For analysis of the reliability growth test data, it is important to distinguish between the terms “failure

intensity” (for repaired items) and “failure rate” or “instantaneous failure rate” (for non-repaired or one-shot items)

defined in IEC 60050(191).
3.1
item
entity

any part, component, device, subsystem, functional unit, equipment or system that can be

individually considered

NOTE An item may consist of hardware, software or both, and may also, in particular cases, include people.

[IEC 60050, 191-01-01]
3.2
reliability improvement

process undertaken with the deliberate intention of improving the reliability performance

by eliminating causes of systematic failures and/or by reducing the probability of occurrence

of other failures
[IEC 60050, 191-17-05]

NOTE 1 The method described in this standard is aimed at making corrective modifications aimed at reducing

systematic weaknesses or reducing their likelihood of occurrence.

NOTE 2 For any item, there are limits to practicable and economic improvement and to achievable growth.

3.3
reliability growth

condition characterized by a progressive improvement of a reliability performance measure

of an item with time
[IEC 60050, 191-17-04]

NOTE Modelling (projection) and analysis of reliability improvement during the design phase is based on the

standard estimation of the expected product reliability within a given time period.

3.4
integrated reliability engineering

engineering tool, consisting of a multitude of reliability/dependability methods integrated into

all engineering stages and activities regarding a product, from the conceptual phase through

its use in the field by a combination of contributions from all relevant stakeholders

3.5
product reliability goal

reliability goal for a product based on certain corporate targets, market requirements or

desired mission success probability that is reasonably achievable according to the past

history and technical evolution

NOTE For some projects, the reliability goal is set by the customer. The product specific goal is the target value

of the reliability growth process.
3.6
systematic weakness

weakness, which can be eliminated, or its effects reduced, only by a modification of the

design or manufacturing process, operational procedures, documentation or other relevant

factors, or by replacement of substandard components by components of proven superior

reliability

NOTE 1 A systematic weakness often results in a failure that is related to a weakness in the design or

a weakness of the manufacturing process or documentation.
---------------------- Page: 13 ----------------------
61014  IEC:2003 – 17 –

NOTE 2 Repair or replacement (or re-run in case of software) without modification is likely to lead to recurrent

failures of a similar kind.
NOTE 3 Software weaknesses are always systematic.
3.7
residual weakness
weakness, which is not systematic

NOTE 1 In this case, risk of recurrent failure of a similar kind is small or even negligible, within the expected test

time scale.
NOTE 2 Software weaknesses cannot be residual.
3.8
failure
termination of the ability of an item to perform a required function
NOTE 1 After failure the item has a fault.
NOTE 2 “Failure” is an event, as distinguished from “fault”, which is a state.
[IEC 60050,191-04-01]

NOTE 3 The term “termination” implies that the product had the ability to perform a required function and then

lost it. Once the system design is capable of meeting the specified performance requirement, then reliability failure

is the termination of this capability.
3.9
failure mode

manner in which any system or component ceases to perform its respective designed

operation

NOTE 1 A failure mode may be characterized by its frequency of occurrence or by probability of its occurrence to

include into the system’s or component’s reliability.

NOTE 2 To address the reliability of a system, fundamentally its corresponding failure modes, the causes of these

failure modes, and the frequency or probability of occurrence of these modes under the system’s intended use

environment need to be addressed.
3.10
relevant failure

failure that should be included in interpreting test or operational results or in calculating the

value of a reliability performance measure
NOTE 1 The criteria for inclusion should be stated.
[IEC 60050, 191-04-13]
NOTE 2 The criteria for inclusion are stated in 6.4.6.
3.11
non-relevant failure

failure that should be excluded in interpreting test or operational results or in calculating

the value of a reliability performance measure
[IEC 60050, 191-04-14]
NOTE The criteria for classifying failures as not relevant are stated in 6.4.5.
3.12
systematic failure

failure that exhibits, after a physical, circumstantial or design analysis, a condition or pattern

of failure that may be expected to cause recurrence

NOTE 1 Corrective maintenance without modification does not usually eliminate the failure cause.

NOTE 2 A systematic failure can be induced at will by simulating the failure cause.

NOTE 3 In this standard, a systematic failure is interpreted as a failure resulting from a systematic weakness.

3.13
residual failure
failure resulting from a residual weakness
---------------------- Page: 14 ----------------------
61014  IEC:2003
...

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