1、BRITISH STANDARD BS 6548-1: 1984 IEC 60706-1: 1982 Incorporating Amendment No. 1 Maintainability of equipment Part 1: Guide to specifying and contracting for maintainability UDC 658.58:621.3 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBS 6548-1:1984 This British Standard, h
2、aving been prepared under the direction of the General Electrotechnical Engineering Standards Committee, was published under the authority of the Board of BSI and comes into effect on 31 December 1984 BSI 31 October 2001 The following BSI references relate to the work on this standard: Committee ref
3、erence GEL/6 Drafts for comment 79/20484 DC 79/20485 DC 77/22773 DC ISBN 0 580 14220 5 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the General Electrotechnical Engineering Standards Committee (GEL/-) to Technical Committee GEL/6 upon whi
4、ch the following bodies were represented: Atomic Energy Research Establishment (AERE) British Telecommunications ERA Technology Ltd. Electricity Supply Industry in England and Wales Electronic Components Industry Federation Electronic Engineering Association Institute of Quality Assurance Institutio
5、n of Electronic and Radio Engineers Ministry of Defence Society of British Aerospace Companies Limited Telecommunication Engineering and Manufacturing Association (TEMA) Coopted member Amendments issued since publication Amd. No. Date of issue Comments 13156 31 October 2001 Deletion of sections 1 an
6、d 3BS 6548-1:1984 BSI 31 October 2001 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope 1 Section 1. Introduction to maintainability Section deleted 1 Section 2. Maintainability requirements in specifications and contracts 5 Introduction 1 6 Maintainability requi
7、rements 2 7 Verification 4 Section 3. Maintainability programme Section deleted 5 Appendix A Examples of the information the customer should give to the contractor Appendix deleted 6 Table I Examples of quantitative maintainability requirements 4 Table II Examples of qualitative subjects for which r
8、equirements may be specified 4BS 6548-1:1984 ii BSI 31 October 2001 National foreword This British Standard guide has been prepared under the direction of the General Electrotechnical Engineering Standards Committee and is identical with IEC 60706-1:1982, section 2, published by the International El
9、ectrotechnical Commission (IEC). Sections 1 and 3 have been withdrawn by amendment and have been superseded by BS IEC 60300-3-10:2001. Additional information. As this is a guide, where the words “shall” and “must” appear implying a requirement, they should be read as “should”. A British Standard doe
10、s not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an insi
11、de front cover, pages i and ii, pages 1 to 6, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issuedBS 6548-1:1984 BSI 31 October 2001 1 1 Scope This guide is intended to make recommendations for the standardization of m
12、aintainability practices, and to stimulate ideas in the maintainability field. Organizations acquiring items will find the guide useful in assisting them in defining maintainability requirements and associated programmes. Item suppliers will benefit from use of the guide, gaining an understanding of
13、 the requirements for achieving and verifying maintainability objectives. This publication comprises section 2 of the Guide on Maintainability. Titles for all the sections of this series are: Section 1 1) Introduction to maintainability (section deleted). Section 2 1) Maintainability requirements in
14、 specifications and contracts. Section 3 1) Maintainability programme (section deleted). Section 4 Test and diagnostic procedures. Section 5 Maintainability design studies. Section 6 Maintainability verification. Section 7 Collection, analysis and presentation of data related to maintainability. Sec
15、tion 1. Introduction to maintainability Section deleted (superseded by BS IEC 60300-3-10:2001). Section 2. Maintainability requirements in specifications and contracts 5 Introduction This section of the series is not intended to be a complete guide on how to specify or to contract for maintainabilit
16、y. The purpose is to discuss the general scope that has to be considered when maintainability characteristics are included as requirements on the development or the acquisition of an item. Maintainability is a characteristic defining inherent properties of an item and the corresponding discipline is
17、 concerned with how well an item can be maintained and supported during its use period. Maintainability must be built into the item during the design and development phase and thus it is important that maintainability requirements be established as part of the initial item specification. The develop
18、ment of an item may be thought of as a process evolving from a need for a certain function, all the way through a step-by-step definition of that item satisfying the same need, ending up with an item ready for operational use. The process must be controlled in order to result in an item satisfying n
19、eeds at the right instant of time and at a reasonable cost. This concept is valid independent of whether a new item is actually designed or a specific need is transferred into a selection of an off-the-shelf item. The maintainability requirements in a specification may contain either quantitative or
20、 qualitative requirements or both. The methods for verifying that the requirements have been satisfied should be stated. The existence of special constraints which might affect the items maintainability characteristics should also be stated. 1) Included in this publication.BS 6548-1:1984 2 BSI 31 Oc
21、tober 2001 6 Maintainability requirements A complete statement of maintainability requirements will cover four broad areas: maintainability characteristics to be achieved by the item design; constraints to be placed on the item deployment which will affect its maintenance; maintainability programme
22、requirements to be accomplished by the supplier to assure that the delivered item has the required maintainability characteristics; provision of maintenance support planning. The maintainability specification should detail the requirements and the method to be followed to achieve them. It should als
23、o include proper references to definitions of terms used in the specification and, as needed, a list of special terms. The specification may be stated as goals or in terms of firm requirements which shall be verified in accordance with prescribed procedures 2) . Goals or requirements may be stated i
24、n either quantitative or qualitative terms. A maintainability specification typically covers the various aspects of maintainability achievement at the operational level. However, since maintainability as an item characteristic affects maintenance and support costs and may also affect maintenance tim
25、es at different maintenance levels, statements should be included in the specification covering achievements needed at all levels affected by the maintenance policy. 6.1 Maintainability characteristics 6.1.1 Quantitative maintainability requirements The most common objective is related to the time a
26、n item is in a non-operable status due to maintenance. Obviously, one would like to keep this time as short as possible. There is a wide range of requirements that could be used to this effect. The difference between them will be that they express different priorities between related item properties
27、 and that they allow for different flexibility concerning trade-offs to be made later in the programme. It is important that such factors are considered before a specific requirement is included in the specification. Active repair time is often used to specify maintainability and includes the follow
28、ing sub-elements: diagnosis (failure detection, localization of cause, etc.); technical delays (typical technical delays include setting time, cooling, interpretation and application of information, interpretation of displays, read out, etc.); restoration (disassembly, interchange, reassembly, align
29、ment, etc.); final check (testing procedures as necessary). A variety of other maintainability characteristics may be specified for the item. Table I outlines some other types of requirements associated with different classes of maintenance time and verification methods. 6.1.2 Qualitative maintainab
30、ility requirements A second achievement to look for is related to the degree to which the item concurs to a specific maintenance and support policy. Where the qualitative requirement contains numerical values, it should be qualified by a statement of the degree to which it should be met. This could
31、be done by proportions of cases or events, by confidence levels or by other probabilities. Otherwise, compliance must be judged by inspection or document review. Such policies could include statements such as the following examples: repair shall be performed by personnel of stated skill level; repai
32、r shall be performed by replacement of recoverable units; replaceable parts will be plug-in units; maintenance shall be performed according to defined and established procedures; failed part isolation shall be performed by built-in test equipment for 95 % of all cases. Table II presents a range of o
33、ther possible qualitative subjects which may be of concern. 2) In this guide a goal is considered as a desirable feature which is not mandatory whereas a requirement must be provided.BS 6548-1:1984 BSI 31 October 2001 3 6.2 Constraints When writing a specification, not only should requirements be st
34、ated on how things should be done, but in most cases there are also constraints on ways of meeting requirements which for various reasons cannot be accepted (for example, no preventive maintenance will be allowed during certain periods of time). Failure to specify constraints might give the designer
35、 the opportunity to fulfil his maintainability requirements at the expense of the user in terms of more expensive instrumentation, etc. Constraints needed in a specification depend on the nature of the maintainability requirements discussed in Sub-clause 6.1 It is advisable explicitly to examine thi
36、s need for each objective stated. Generally, such constraints will include a basic maintenance and support policy together with limits for critical resources like expensive instrumentation, high cost spares, and skill and number of personnel at each level in the organization. Some statement putting
37、requirements on the amount and the nature of preventive maintenance will often be included in the specification. Special emphasis must be given to constraining critical resources to be held on site. Emphasis must also be given to constraining periods of time, relative to expected utilization of the
38、equipment, when preventive maintenance can be carried out. Constraints may also be introduced by reference to other specifications, IEC publications or other publications. 6.3 Programme requirements There are several reasons why a specification should include requirements for a formal maintainabilit
39、y programme to be used by the supplier in his efforts to satisfy requirements: it facilitates co-ordination between several suppliers delivering items to be used in the same system; it can establish an interface between item development and the development of a maintenance and support system; the cu
40、stomer-supplier interaction defined by a programme could be looked upon as part of a verification that requirements have been fulfilled; more flexibility for trade-offs can be allowed with a formal programme requirement. Specific details on maintainability programmes are given in BS IEC 60300-3-10:2
41、001. 6.4 Engineering support planning To obtain a cost-effective system it is not sufficient to acquire an item satisfying requirements. A maintenance and support system must also be designed to fit the situation. Resources needed to maintain and support the system must be acquired. This task shall
42、as far as possible be integrated with the acquisition of the equipment to be supported. This can be achieved in two ways or by a combination of them: the supplier is given the responsibility of providing some of the resources needed to fulfil maintenance requirements, for example training, manuals,
43、test equipment, spares, etc.; the supplier is given the responsibility of providing, according to a schedule, engineering support planning data such as: failure rates and repair times; list of special tools and instrumentation; list and cost of spares; test specifications; training requirements; etc
44、. Maintenance support data are generally developed by means of maintenance engineering and support analysis.BS 6548-1:1984 4 BSI 31 October 2001 7 Verification Verification of maintainability requirements is the process of determining that the requirements imposed in the specification have been achi
45、eved and the verification process should be defined in the maintainability requirements. Methods of verification may range from the submission by the supplier of appropriate data or information to a requirement to perform a special maintainability demonstration. Section 6 of this guide discusses in
46、some detail the alternative verification methods. Table I Examples of quantitative maintainability requirements Table II Examples of qualitative subjects for which requirements may be specified Term Characteristic Verification method Active maintenance time Mean, median or maximum b Design evaluatio
47、n, demonstration or operational evaluation Active repair time (corrective) Mean, median or maximum b Design evaluation, demonstration or operational evaluation Active preventive maintenance Mean, median or maximum b Design evaluation, demonstration or operational evaluation Routine inspection interv
48、al Value Design evaluation, operational evaluation Maintenance cost per operating hour a Mean Design evaluation, operational evaluation Number of hours of labour per operating hour a Mean Design evaluation, operational evaluation Number of personnel per maintenance action a Mean Design evaluation, o
49、perational evaluation Maintenance support cost for life cycle a Mean Design evaluation, operational evaluation a Other time bases may be selected as appropriate i.e., day, month, year, etc. b The maximum value must be associated with a percentile a commonly used value is 95 %. 1. Maintenance skill level requirements. 2. Need for special tools or test equipment. 3. Need for adjustments. 4. Parts standardization. 5. Clear subsystem function identification. 6. Visual inspection access. 7. Built-in test facilit
