NORME INTERNATIONALE CEI IEC INTERNATIONAL STANDARD 60300 3 10 Première édition First edition 2001 01 Gestion de la sûreté de fonctionnement � Partie 3 10 Guide d''''application � Maintenabilité Dependab[.]
Définitions
Maintainability refers to the ability of an entity to be kept or restored to a state where it can perform a required function under specified usage conditions This capability is achieved when maintenance is carried out according to prescribed procedures and means.
NOTE Le terme ômaintenabilitộằ est aussi employộ comme caractộristique de cette aptitude (voir 191-13-01).
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IEC 60300-3-2, Dependability management – Part 3: Application guide – Section 2: Collection of dependability data from the field
IEC 60300-3-3, Dependability management – Part 3: Application guide – Section 3: Life cycle costing
IEC 60300-3-9, Dependability management – Part 3: Application guide – Section 9: Risk analysis of technological systems
IEC 60300-3-11, Dependability management – Part 3-11: Application guide – Reliability centred maintenance
IEC 60706 (all parts), Guide on maintainability of equipment
IEC 60706-2, Guide on maintainability of equipment Part 2 – Section Five: Maintainability studies during the design phase
IEC 60706-3, Guide on maintainability of equipment Part 3 – Sections Six and Seven.
Verification and collection, analysis and presentation of data
IEC 60706-4, Guide on maintainability of equipment – Part 4 – Section 8: Maintenance and maintenance support planning
IEC 60706-5, Guide on maintainability of equipment – Part 5: Section 4: Diagnostic testing
IEC 60812, Analysis techniques for system reliability – Procedure for failure mode and effects analysis (FMEA)
IEC 60863, Presentation of reliability, maintainability and availability predictions
IEC 61025, Fault tree analysis (FTA)
For the purposes of this standard, the definitions given in IEC 60050(191) and the following apply.
Maintainability refers to the capability of an item to be kept in or restored to a condition that allows it to perform its intended function This is achievable under specific usage conditions, provided that maintenance is conducted according to established procedures and with the appropriate resources.
NOTE The term "maintainability" is also used as a measure of maintainability performance (see 191-13-01).
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Maintainability for a specific entity, under defined usage conditions, refers to the likelihood that a particular active maintenance operation can be performed within a specified time frame This probability is contingent upon the maintenance being conducted under set conditions and utilizing prescribed procedures and resources.
NOTE Le terme ômaintenabilitộằ est aussi employộ pour dộsigner l'aptitude caractộrisộe par cette probabilitộ
3.1.3 maintenance combinaison de toutes les actions techniques et administratives, y compris les opérations de surveillance, destinées à maintenir ou à remettre une entité dans un état lui permettant d'accomplir une fonction requise
3.1.4 échelon de maintenance position, au sein d'une organisation, ó des niveaux de maintenance spécifiés sont effectués sur une entité
NOTE 1 L'échelon de maintenance peut correspondre par exemple à la maintenance sur site, dans un atelier de réparation ou chez le constructeur.
NOTE 2 L'échelon de maintenance est caractérisé par la compétence du personnel, les moyens disponibles, l'emplacement, etc.
3.1.5 niveau de maintenance ensemble des opérations de maintenance à effectuer à un niveau d'intervention spécifié
NOTE Les opérations de maintenance peuvent consister par exemple à remplacer un composant, une carte de circuit imprimé, un sous-système.
3.1.6 concept de maintenance l’application d’une politique de maintenance globale à un produit particulier
3.1.7 politique de maintenance relation globale entre les niveaux de maintenance et les échelons de maintenance et les conditions de la maintenance à appliquer pour la maintenance d’un produit
The procurement process involves determining and acquiring the appropriate lot and quantity of spare parts, repair components, and necessary logistics and testing equipment to ensure the operation and maintenance of a product throughout its initially specified service life.
3.1.9 aptitude au soutien degré avec lequel la conception d'un système et les moyens logistiques planifiés, y compris la main d'œuvre, satisfont aux exigences opérationnelles d'utilisation du système
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Maintainability refers to the likelihood that a specific maintenance action can be executed within a designated time frame for an item, given certain usage conditions This probability is contingent upon performing the maintenance under specified conditions and utilizing defined procedures and resources.
NOTE The term "maintainability" is also used to denote the maintainability performance quantified by this probability (see 191-02-07).
Maintenance encompasses a range of technical and administrative actions, including supervision, aimed at keeping an item in optimal condition or restoring it to a state where it can effectively perform its intended function.
3.1.4 maintenance echelon (line of maintenance) a position in an organization where specified levels of maintenance are to be carried out on an item
NOTE 1 Examples of maintenance echelons are: field, repair shop, manufacturer.
NOTE 2 The maintenance echelon is characterized by the skill of the personnel, the facilities available, the location, etc.
3.1.5 level of maintenance the set of maintenance actions to be carried out at a specified indenture level
NOTE Examples of a maintenance action are replacing a component, a printed circuit board, a subsystem, etc.
3.1.6 maintenance concept application of a general maintenance policy to a specific item
3.1.7 maintenance policy general interrelationship between levels of maintenance, lines of maintenance and maintenance conditions to be applied for the maintenance of an item
The provisioning process involves identifying and obtaining the necessary range and quantity of spare parts, repair components, and support equipment essential for the effective operation and maintenance of a product during its initial service period.
3.1.9 supportability degree to which system design characteristics and planned logistic resources, including manpower, meet system operational utilization requirements
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Acronymes
ETA equipement de test automatique
ETI equipement de test intégré
AMDE analyse des modes de défaillance et de leurs effets
AMDEC analyse des modes de défaillance, de leurs effets et de leur criticité
AAP analyse par arbre de panne
CCV cỏt du cycle de vie
URL unitộ remplaỗable en ligne
MTMA moyenne des temps de maintenance active
MTTR moyenne des temps des tâches de réparation
NDI produit non soumis à développement
MBF maintenance basée sur la fiabilité
4 Présentation générale de la maintenabilité
Généralités
Maintainability refers to the ease, cost-effectiveness, safety, and accuracy with which maintenance can be performed on a product It can be measured in terms of probability or the resources required for upkeep Consequently, maintainability directly impacts a product's ability to meet performance requirements Maintenance encompasses all actions taken to preserve or restore this capability.
Cette distinction apparaợt à l’article 3 dans les dộfinitions des termes ômaintenabilitộằ et ômaintenanceằ extraites de la CEI 60050(191).
When designing a product, it is essential for the designer to consider how the system and its components will be maintained Therefore, maintainability and the achievement of performance objectives are directly influenced by design decisions and activities.
Designers must consider how individuals interact with systems and equipment, emphasizing the importance of industrial safety, human factors, and accessibility during the design phase.
To effectively incorporate maintenance factors into relevant logistics areas such as spare parts supply, technical documentation, and training, it is essential to develop a maintainability program This program comprises a series of intentional and systematic tasks that must be integrated into design activities and is a vital component of the reliability program, which plays a crucial role in the overall project management.
Cycle de vie du produit
Phase de concept et de définition
It is crucial to consider a product's maintainability from the initial phase, typically the concept and definition stage, to establish a clear maintenance policy The design of a product will be significantly influenced by maintenance requirements, and important parameters should be taken into account during this stage.
– les conditions d'environnement dans lesquelles l'équipement sera exploité et maintenu;
– l’importance de la maintenance préventive;
– la durée de vie requise du produit et la méthode de mise au rebut;
Phase de conception et de développement
Maintainability should be considered in detail as an integral part of product design Maintainability studies, along with reliability studies, are conducted to translate operational requirements into detailed, qualitative, and quantitative maintainability requirements and design criteria.
En particulier, ces études concernent
– les niveaux de qualification du personnel de maintenance;
– les échelons de maintenance proposés;
– le type et le montant de la maintenance à effectuer à chaque ôộchelon de maintenanceằ
– la moyenne des temps des tâches de réparation (MTTR);
The use of established and conventional maintainability standards is recommended to effectively contribute to detailed design work These standards are accessible across various industrial sectors and provide guidelines for addressing a range of design issues related to industry-specific maintainability Additional guidance on maintainability studies and related activities at this level is provided in IEC 60706-2.
During this phase, it is essential to consider maintenance support to ensure the product operates satisfactorily Additional guidance on maintenance support can be found in section 6.9 and in IEC 60706-4.
Phase de fabrication
Ideally, functional parameter verification should occur during product development, including testing of prototypes or initial series of standard equipment However, these results may not accurately reflect the standard outcomes for production models Additionally, the testing procedure may still be under development While maintainability verification results obtained during this phase are valuable, a comprehensive verification to ensure that maintainability objectives have been met must wait until representative equipment is produced.
Davantage d'indications sur la vérification sont données en 6.7 et dans la CEI 60706-3.
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Considering maintainability from the initial concept and definition phase of a product is crucial for establishing a clear maintenance policy The design will be significantly shaped by maintenance requirements, and key parameters must be taken into account during this stage.
– environmental conditions in which equipment will operate and be maintained;
– the life required from the product and the method of disposal;
Maintainability should be considered in detail as an integral part of the design of the product.
Maintainability studies, in conjunction with reliability studies, are undertaken to translate operational requirements into detailed qualitative and quantitative maintainability requirements and design criteria.
In particular, these studies should address
– the proposed lines of maintenance;
– type and amount of maintenance to be carried out by each "line of maintenance" (see 3.1.4);
– mean time to repair (MTTR);
Utilizing established standards for maintainability is essential for enhancing detailed design efforts These standards, prevalent across various industries, provide valuable guidelines for addressing specific maintainability design challenges For additional insights into maintainability studies and related activities during this phase, refer to IEC 60706-2.
During this phase, it is essential to consider maintenance support to ensure the product is fully operational Additional guidance on maintenance support can be found in section 6.9 and IEC 60706-4.
Ideally, verification of functional parameters should have been undertaken during the development of the product and the trials of prototype or early build standard equipment.
The results obtained may not reflect the standards of full production models, and the testing procedures could still be in development Although some maintainability verification results from this period will be useful, a complete assessment of whether maintainability targets have been met will depend on the production of representative equipment For additional guidance on verification, refer to section 6.7 and IEC 60706-3.
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Phase d'installation
The installation of equipment or processes presents a crucial opportunity to evaluate the features of a complex product or system During this phase, key indicators include accessibility, as well as the ability to lift, install, test, and store components effectively.
Phase d'exploitation et de maintenance
When the product is commissioned, it is essential to verify maintainability through measurements A maintenance data acquisition system should be established to assess maintainability parameters and identify maintenance issues.
Davantage d'indications sur le recueil des données de maintenance sont données en 6.11 et dans la CEI 60706-3.
Phase de mise au rebut
The decision to retire a product is influenced by its ability to function adequately, along with its reliability, maintainability, and operational costs These factors are contingent upon the continuous supply of spare parts, logistical support, and the availability of replacement equipment.
Généralités
The lifespan and intrinsic reliability of a product can only be achieved through proper maintenance While disposable products do not require maintenance, most products will inevitably experience failures that necessitate corrective maintenance Additionally, preventive maintenance can effectively ensure safe and economical operation based on failure characteristics, costs, and criticality When preventive maintenance is both effective and economical, operational availability can be increased, and the frequency of corrective maintenance can be reduced.
To ensure acceptable maintainability of a product in a systematic and planned manner, it is essential to integrate a maintainability program alongside a reliability program into the overall design process of a project.
Il convient qu’un tel programme de maintenabilité comporte les éléments suivants:
– gestion et organisation des activités pour assurer une mise en œuvre efficace du programme;
– un ensemble de tâches d’analyse de la maintenance à exécuter pendant le processus de conception;
– le soutien de spécialistes pour définir les informations nécessaires au programme.
Il convient que les objectifs d'un tel programme soient d'optimiser l'efficacité du système en respectant les contraintes suivantes:
– un équilibre entre la disponibilité d'un produit et les cỏts éventuels du cycle de vie (CCV) qui en découlent;
– un équilibre entre la maintenance et la logistique de maintenance requise, et les cỏts éventuels du cycle de vie (CCV) qui en découlent;
– une élimination des dangers affectant la sécurité.
La figure 1 montre la relation entre le processus de conception et les tâches de maintenabilité associées.
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The installation of equipment presents a crucial opportunity to evaluate the maintainability features of a complex system Key factors during this phase include accessibility, the capability to lift and install components, and the processes for aligning and testing them.
To ensure effective operation, it is essential to verify the maintainability of the product through measurement Establishing a maintenance data acquisition system is crucial for estimating maintainability parameters and identifying potential maintenance issues For additional guidance on maintenance data collection, refer to section 6.11 and IEC 60706-3.
The decision to dispose of a product is influenced by its functionality, reliability, maintainability, and operational costs These factors are contingent upon the ongoing availability of spare parts, support, and replacement equipment.
The reliability and longevity of a product depend on proper maintenance While disposable items may not require maintenance, most products will inevitably experience failures that necessitate corrective maintenance Implementing preventive maintenance can enhance safety and cost-effectiveness, particularly when considering the product's failure characteristics and criticality When preventive maintenance is both effective and economical, it can improve operational availability and decrease the need for corrective maintenance.
In order to achieve acceptable product maintainability in a planned and systematic manner, a maintainability programme, in conjunction with a reliability programme, should be integrated with the overall project design process.
Such a maintainability programme should have the following elements:
– management and organizational activities to ensure effective and efficient implementation of the programme;
– a set of maintainability analysis tasks to be performed during the design process;
– specialist support activities to provide the necessary information for the programme.
The objectives of such a programme should be to optimize system effectiveness with respect to the following constraints:
– balancing product availability against possible life cycle costs (LCC);
– balancing maintenance and maintenance support requirements against possible life cycle costs (LCC);
Figure 1 shows the relationship between the design process and the maintainability related design tasks.
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Processus de conception d’un produit
Tâches de conception relatives à la maintenabilité
Plan des ressources de soutien logistique de maintenance
Analyse du retour d’expérience (par exemple centrale électrique/niveau système global Prescriptions de fiabilité et de maintenabilité du produit Concept de maintenance
Concept de maintenance Etude du produit/système Vérification préliminaire de maintenabilité
Analyse du retour d’expérience (niveau système/niveau équipements) Prescriptions de fiabilité et de maintenabilité du système
Etudes de remplacement d’équipements Analyse des accès
Analyse préliminaire de fiabilité et de maintenabilité
Analyse détaillée de fiabilité et de maintenabilité Analyse préliminaire de maintenance préventive (MBF) Analyse et identification préliminaires des tâches de maintenance Vérification de maintenabilité
Prescriptions détaillées des clauses de fiabilité et de maintenabilité des équipements Surveillances des programmes de fiabilité et de maintenabilité des fournisseurs
Mise à jour de l’analyse de maintenance préventive (MBF) Mise à jour de l’analyse et de l’identification des tâches de maintenance Mise à jour de l’analyse de fiabilité et de maintenabilité
Revues préliminaires de la vulnérabilité des équipements Vérfication de maintenabilité
Mise à jour des études de transfert des équipements Mise à jour des revues des itinéraires d’accès
Revues préliminaires de vulnérabilité des équipements Vérification de maintenabilité
Mise à jour de la conception du système pour tenir compte des détails des équipements
Construction et mise en service
Ressources de soutien logistique de maintenance (concept)
Ressources de soutien logistique de maintenance (phase préliminaire)
Ressources de soutien logistique de maintenance (détails)
Figure 1 – Processus de conception et tâches de maintenabilité relatives à la conception
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Product Maintainability Maintenance design related support process design tasks resources plan
Past experience review (e.g power plant/major system level) Product reliability and maintainability requirements
Maintenance concept Product/system layout Preliminary maintainability verification
Past experience review (system/equipment level) System reliability and maintainability requirements
Equipment replacement studies Access reviews
Preliminary reliability and maintainability analysis
Detailed reliability and maintainability analysis Preliminary preventive maintenance (RCM) analysis Preliminary maintenance task identification and analysis Maintainability verification
Detailed equipment reliability and maintainability clause requirements
Monitoring of supplier's reliability and maintainability programmes
Update preventive maintenance (RCM) analysis Update maintenance task identification and analysis
Preliminary equipment vulnerability reviews Maintainability verification
Update equipment transfer studies Update access route reviews
Preliminary equipment vulnerability reviews Maintainability verification
Update system design to reflect equipment details
Maintenance support resources (detailed) Update reliability and maintainability analysis
Figure 1 – Design process and the maintainability related design tasks
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Critères pour le développement de programmes de maintenabilité
Application de l'utilisateur
Le besoin de spécifier des exigences de maintenabilité et de réaliser un programme de maintenabilité pour un produit et son soutien logistique dépend des conditions du marché
(utilisateur final) qui, dans tous les cas, prévalent.
Maintainability considerations are influenced by factors such as product lifespan, reliability, safety, availability, and financial aspects related to varying market conditions For instance, aircraft and nuclear power plants require a high level of safety, which dictates stringent maintenance requirements In contrast, for other products, the maintenance costs associated with operational expenses can be a significant factor in determining the necessary level of maintainability.
The significance of maintainability as a specific aspect of product design or logistical support can differ for each product type, necessitating a tailored maintenance program to meet the specific requirements associated with that product.
Facteurs relatifs au produit
Il convient que les facteurs suivants relatifs au produit soient considérés.
– Les exigences de maintenabilité Le niveau de maintenabilité et de logistique de maintenance requis pour assurer une disponibilité spécifiée.
The complexity of a product influences the intricacy of its maintenance logistics For instance, the extent to which integrated test equipment (ITE) is utilized will depend on the required level of diagnostics.
Mature products have well-established maintenance procedures; however, it is essential to consider the impact of experimental technologies and the necessity to develop appropriate design procedures for less mature products.
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5.2 Criteria for the development of maintainability programmes
A maintainability programme must be customized for each specific product or project, taking into account the relevant conditions, requirements, and complexity The comprehensive maintainability programme outlined in the subsequent sections is intended for large and complex products developed from concept to production For simpler products or existing designs, a streamlined programme can be implemented, utilizing only the applicable components that align with the complexity and customer requirements.
To develop an effective maintainability program throughout the product life cycle, it is essential to understand maintainability principles, methods, and techniques Additionally, a comprehensive knowledge of the product, its technology, intended use, associated costs, design, and customer expectations is crucial.
In order to obtain effective results, maintainability activities should be integrated with the other design and development activities rather than managed separately.
In the development of a maintainability programme, the following factors should be taken into account.
The need to specify maintainability requirements and to implement a maintainability pro- gramme for a product and its support depends on the market (end user) condition prevailing in each case.
Maintainability considerations depend on requirements such as product life, reliability, safety and availability and on the financial considerations related to different market situations.
Flight systems and nuclear power plants necessitate stringent safety measures, leading to increased maintenance demands In contrast, for other products, maintenance costs relative to operating expenses often play a crucial role in determining the necessary level of maintainability.
Maintainability is a crucial design and support factor that differs across various product types, necessitating a customized maintainability program to address the specific needs of each product.
The following product related factors should be considered.
– Maintainability requirements The level of maintainability performance and maintenance support required to provide a specified availability performance.
The complexity of a product directly influences the intricacy of its maintenance support facilities For instance, the extent of built-in test equipment (BITE) utilized is contingent upon the necessary level of diagnostic capability.
Mature products feature established maintenance procedures, while less mature products require consideration of unproven technology and the development of suitable procedures tailored to their design.
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Critical maintenance is essential when safety is a primary concern, with nuclear power plants and aircraft serving as clear examples of critical products Additionally, economic and operational issues can also be deemed critical, such as the failure of a process or manufacturing facility.
Technical constraints can complicate design processes, as they involve parameters that are beyond the designer's control This often leads to the need for more complex maintenance actions.
Tight schedules and budget constraints can limit design flexibility in optimizing operational safety Additional maintenance actions may need to be considered to meet safety requirements effectively.
– Les conditions de la logistique de maintenance La politique de maintenance et les niveaux de qualification du personnel à disposition de l'exploitant peuvent influencer l'efficacité des tâches.
– Les conditions d’exploitation La sévérité de l’environnement, la durée d’utilisation et les cycles d’exploitation peuvent imposer la fréquence des actions de maintenance.
– Transport et stockage Des actions de maintenance peuvent être nécessaires avant et après le stockage, la manutention et le transport.
Customer-related factors define the client's maintenance experience and influence the extent to which the client's personnel will perform maintenance actions Additionally, these factors highlight the significance of the product to the client.
Factors related to the supplier, such as their maintenance experience and the level of logistical support they provide, will determine the location of maintenance activities and the extent of maintenance that can be performed.
Regulatory requirements established by governments and other statutory bodies must be considered, and all relevant regulatory maintenance tasks should be incorporated into the maintenance program.
Environmental emissions must be managed effectively, ensuring that the discharge limits set by clients or external regulations are consistently met, even as equipment experiences wear and tear.
Planification et contraintes
Politique de maintenance
The maintenance policy serves as the overarching connection between various maintenance levels, tiers, and the conditions necessary for product upkeep It outlines the client's general maintenance strategy, providing insights into the organization of their logistical support.
A set of design practices and objectives related to maintainability is essential for a project or product classes These practices may include standardizing similar product types across an entire installation and utilizing quickly interchangeable modular components.
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Criticality Maintenance is essential in areas where safety is paramount, with nuclear plants and aircraft serving as prime examples of safety-critical products Additionally, operational and economic factors can also be deemed critical, particularly in situations involving the failure of processing or manufacturing plants.
– Technical constraints When the design is constrained by technical or physical parameters beyond the control of the designer, more complex maintenance actions may be required.
– Programme constraints Tight schedules or funding limitations may restrict freedom of design for optimum dependability Additional maintenance actions may have to be considered to meet the dependability requirements.
– Maintenance support conditions The maintenance policy and personnel skill levels of staff available to the operator may influence task effectiveness.
– Operational conditions Environmental severity, time in use and operating cycles may govern the frequency of maintenance actions.
– Storage and transportation Maintenance actions may be required prior to, and following, storage, handling and transportation.
– Customer related factors The customer's maintenance experience and the extent to which the customer's staff will carry out maintenance actions The importance of the product to the customer.
Supplier-related factors, including the supplier's maintenance experience and the extent of maintenance support offered, significantly influence the location and level of maintenance activities.
– Regulatory requirements The regulations laid down by Government or other statutory bodies need to be considered and any relevant mandated maintenance tasks included in the maintenance programme.
– Environmental emissions Maintenance of a product has to ensure that the emission limits set by the customer or external regulation continue to be met as equipment deteriorates.
In the product life cycle, it is essential to evaluate the relevant phases, especially when a full development program is not necessary This assessment should include an analysis of maintainability to ensure that all requirements are effectively met.
6 Maintainability programme elements and tasks
The first task in the preparation of a maintainability programme is to determine the maintenance policy and maintenance concept.
The maintenance policy is the general interrelationship between levels of maintenance, lines of maintenance and maintenance conditions to be applied for the maintenance of an item.
This describes the client's general maintenance policy by giving information on how his support organization is structured, and should result in
This article outlines essential design practices and objectives focused on maintainability for both the project and specific product categories Key aspects include the standardization of similar product types by manufacturers across a facility and the implementation of quick change modules to enhance efficiency.
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– une définition de la démarche de maintenance de base pour des composants significatifs, majeurs et spécifiques d'un produit Cette démarche peut inclure
The maintenance will be conducted by various teams, including those working in shifts and during daytime hours It will take place both on-site and in the workshop, depending on the operational status, such as during shutdowns.
To reduce downtime, several strategies can be implemented, including the use of operational monitoring, integrated testing equipment, straightforward positioning, and verification procedures, as illustrated in Figure 2.
The foundations of the logistics support policy for maintenance encompass essential requirements related to maintenance resources, testing and support equipment, spare parts supply, personnel training and qualification, as well as technical manuals and support software.
Ces facteurs seront basés sur une approche systématique pour améliorer les caractéristiques de fiabilité et de maintenabilité du produit et des composants associés aux équipements.
Il convient que la politique de maintenance soit périodiquement révisée et mise à jour, si nécessaire, avec l'avancement de la conception.
La maintenance préventive peut inclure certains ou tous les éléments décrits pour la maintenance corrective, sauf ceux qui sont relatifs aux pannes
Temps de maintenance (temps d'indisponibilité)
Temps de correction de panne
Temps de réglage et d'étalonnage
Temps de réparation actif Retard
Temps de diagnostic et de localisation de panne
Démontage et remplacement avec un élément identique
Figure 2 – Temps d’indisponibilité actif et inactif utilisé par la maintenance
Concept de maintenance
The maintenance concept involves applying a general maintenance policy to a specific product Developing this maintenance concept requires collaboration between the supplier or designer of the product, the client, and their maintenance advisor.
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– a definition of the basic approach to maintenance of specific, major and significant items of a product, which may include
• what maintenance will be performed, by whom (shift maintainers, day maintainers, etc.), where (in situ, in the shop, etc.) and during what operating states (shut-down, etc.);
To minimize product downtime, several key features are proposed, including condition monitoring, built-in test equipment, and straightforward alignment and checkout procedures, as illustrated in Figure 2.
– basic maintenance support (logistic) policies and requirements relating to maintenance facilities, test and support equipment, spare parts provisioning, personnel skills and training, technical manuals and support software.
These factors will be based on a systematic approach to improving the reliability and maintainability features of the product and of associated items of equipment.
The maintenance policy should be periodically reviewed and updated, if necessary, as the design progresses.
Preventive maintenance may include some or all of the elements described for corrective maintenance except those related to faults
Active repair Delay time time
Fault location and diagnosis time
Access time Test time Cleaning time
Remove and replace with identical item
Figure 2 – Active and inactive downtime spent by maintainers
The maintenance concept involves applying a general maintenance policy to a specific item, necessitating collaboration between the product's supplier or designer and the client along with their maintenance advisor.
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Il convient que le client ait énoncé les grandes lignes de ses exigences vis-à-vis du produit telles que
– le système de contrôle qualité du produit requis pour assurer la maintenance (par exemple normes aéronautiques);
– la durée de vie prévue;
– les exigences relatives à la documentation technique de maintenance;
– l'aptitude du produit à être amélioré ou modifié;
– la méthode de mise au rebut en fin de vie du produit;
– les effets qu'une défaillance ou une indisponibilité du produit auraient vraisemblablement sur l'activité du client ou de l'utilisateur, y compris les conséquences économiques;
Il convient que le client décrive davantage les exigences de maintenabilité en donnant
– une définition des différents niveaux de maintenance;
– les profondeurs de maintenance corrective envisagées à chaque niveau;
– les conditions d'environnement à chaque niveau;
– les ressources disponibles ou planifiées à chaque niveau;
– les limites de la maintenance préventive;
– les temps de rotation maximaux acceptables;
– la formation du personnel de maintenance et des opérateurs sur les tâches de maintenance qui leur incombent;
– les réglementations pertinentes, légales ou statutaires, y compris les effets sur la santé, la sécurité et l'environnement.
The supplier should advise the client on the feasibility and cost of fulfilling their requests, while also suggesting modifications that could simplify the final design The maintenance concept may be revised as the design evolves to achieve the most cost-effective maintenance logistics structure.
Les documents de politique de maintenance et de concept de maintenance deviennent alors la base pour la préparation des spécifications de maintenabilité.
Spécification des exigences de maintenabilité
A maintainability specification should be prepared by either the supplier or the user, as applicable, for the product and its components, as well as for the logistical support required for the product.
Specifications establish a foundational understanding between the client and the supplier, as well as among various groups involved in the design and use of the product.
The development of specifications should begin with defining the types of failures that will impact the effective use of the product, necessitating an analysis and establishment of the following factors.
Quantitative measures of maintainability performance include system maintainability specifications, along with necessary demonstrations and assurances Typically, the maintainability of a system or subsystem is quantified by the Mean Time to Active Maintenance (MTMA), which also considers a maximum maintenance time Additional details may encompass access, the use of specific tools and testing equipment, and connections to any existing maintenance logistical support.
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The client should have stated the broad requirements for the product, such as
– the required product quality system under which maintenance will be performed (e.g. aircraft standards);
– the requirements for technical maintenance manuals;
– the ability for the product to be upgraded or modified;
– the method of disposal at the end of its life;
– the effect that a failure or product non-availability is likely to have on the operations of the client or user, including the economic consequences;
The client should further describe the maintainability requirements by giving information on
– a definition of the various levels of maintenance;
– the depths of corrective maintenance envisaged at each level;
– the environmental conditions at each level;
– the resources available or planned at each level;
– maximum acceptable turn-around times;
– training of maintenance personnel and operators where they are to be involved in maintenance tasks;
– the relevant legal or statutory requirements including health and safety, and environ- mental impact.
The supplier should advise the customer on the feasibility and cost of achieving these requirements and suggest modifications which might facilitate the final design, if appropriate.
The maintenance concept may be revised as the design evolves, in order to produce the most cost effective maintenance support structure.
The maintenance policy and maintenance concept documents then become the basis for the preparation of a maintainability specification.
A maintainability specification should be prepared by the supplier or user, as appropriate, for the product and its parts and for the support requirements of the product.
The specification provides the basis of understanding between the customer and the supplier and among different (supplier and customer) groups of personnel involved with the product's design and use.
The specification development process should begin with identifying the types of faults that could hinder the product's effective use, followed by a thorough analysis to establish the necessary criteria.
– Quantitative measures of maintainability performance The system maintainability specification, along with demonstration and assurance requirements, is part of this task.
The maintainability of a system or subsystem is typically measured by the mean active maintenance time (MAMT), which is accompanied by a specified maximum time Additionally, it may encompass detailed requirements, including accessibility, the use of specialized tools and test equipment, and the integration with existing maintenance support.
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The qualitative maintenance requirements encompass the definition of the product's functions, failure criteria, environmental and operational conditions, and the product's useful life during which these requirements must be met.
– Les prescriptions d’essai Elles comprennent les fonctions et procédures d’essai, la précision des essais à chaque niveau du produit, les prescriptions relatives aux tests intégrés, etc.
Each requirement specification should clearly outline the lifecycle phases during which compliance will be verified, along with the methods and procedures (such as analytical methods, simulations, and tests) that will be used for this verification Additionally, the interdependence between the requirements should be explicitly described.
Il convient que les demandes spộcifiộes aient pour caractộristiques d'ờtre non ambiguởs, complốtes, vộrifiables, cohộrentes et traỗables.
Etudes de maintenabilité
Allocation de maintenabilité
User maintainability requirements at the system level must be allocated as maintainability requirements at the subsystem level The maintainability allocation process involves distributing these requirements to each subsystem, ensuring that their fulfillment allows the system to meet its overall requirements Key parameters in this activity include the time and cost needed to restore a failing system (or subsystem) to an operational state.
The purpose of maintainability allocation is to identify requirements as early as possible so that they can be incorporated into the technical specifications of subsystems This is especially crucial when the design of a subsystem is outsourced.
Il convient que le processus d'allocation de maintenabilité prenne en compte le fait qu’il convient que les produits qui sont les moins fiables soient les plus maintenables.
Il convient que les exigences de maintenabilité soient allouées aux parties d'un produit (ou aux parties du soutien logistique) en considérant
– la structure du produit, des systèmes ou des sous-systèmes;
– le besoin de vérification et de validation des exigences;
It is essential to incorporate maintainability allowances in the specifications for all outsourced components of a final product This will provide a foundation for the verification, specification, and design of testing and validation procedures Such allowances may be reevaluated as a result of trade-off studies during the design progression.
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Qualitative maintainability requirements encompass the definition of product functions, criteria for faults, environmental and operational conditions, and the useful life of the item during which these requirements must be met.
– Testability requirements This includes test functions and procedures, test accuracy of each level of the product, BIT requirements, etc.
Each requirement specification must outline the life cycle phases for verifying conformity, along with the methods and procedures—such as analytical methods, simulations, and tests—used for this verification Additionally, it is essential to clearly describe the interdependence among the requirements.
The specified requirements should have the characteristics of being unambiguous, complete, verifiable, consistent and traceable.
Maintainability studies are undertaken as part of the maintainability programme to quantify the requirements in terms which can be incorporated into the design and development process.
More detailed guidance may be found in IEC 60706-2.
To ensure the overall system meets user maintainability requirements, these needs must be distributed to the subsystem level This maintainability allocation process involves assigning specific requirements to each subsystem, ensuring that their fulfillment leads to the system's compliance Key factors in this process include the time and cost necessary to restore a failed system or subsystem to an operationally ready state.
The purpose of maintainability allocation is to identify these requirements as early as possible so that they can be included in the technical requirements specifications for the subsystems.
This is particularly important when the design of a particular subsystem is to be subcontracted.
The maintainability allocation process should recognize that items which are least reliable should be most maintainable.
Maintainability requirements should be allocated to parts of the product (or to parts of the support process) by considering
– the product's structure and systems or subsystems;
– the need for the verification and validation of the requirements;
Allocations must be specified for all subcontracted components of the final product, serving as a foundation for verification, validation, and testing procedures As the design evolves, these allocations may need to be reassessed based on trade-off studies.
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Analyse de maintenabilité
Le concepteur peut maintenant traduire les demandes du client en exigences de conception en effectuant une analyse de maintenabilité.
Il convient que le concepteur commence par prendre en compte les prescriptions relatives au fonctionnement du produit, à sa disponibilité, à sa fiabilité et à sa maintenabilité Il convient alors que l'analyse
– prépare une description fonctionnelle du produit;
– prépare l'information sur l'espace requis et les dispositions d'accès pour la maintenance;
Develop flow diagrams for maintenance activities based on system overview schematics when necessary These flow diagrams should illustrate the sequence of operations involved in each maintenance activity as outlined by the user's maintenance concept, including disassembly, removal, testing, calibration, repair, and reassembly, while considering various levels and depths of corrective and preventive maintenance.
– identifie les effets, liés au type d'équipement, de la fabrication, du stockage, de l'emballage, du transport, de la manutention et de l'installation sur la maintenance;
– identifie les opérations qui obligent l'utilisateur à développer de nouvelles qualifications ou à utiliser des spécificités liées au type d'équipement;
– fournisse une liste d'unitộs remplaỗables en ligne (URL) qui nộcessiteront d’ờtre remplacées sur la base d’une durée ou d’une usure.
The designer can engage in discussions with the user's maintenance managers to explore solutions, either by modifying the design or by adjusting the maintenance concept.
The simultaneous development of a product and its testing methods can lead to challenges, particularly when the capabilities of these testing methods remain poorly defined for an extended period during the development process, similar to the requirements for testing the product itself.
Interprétation des exigences
Il convient que les conditions et les contraintes qui sont spécifiques à l'usage prévu du produit et qui peuvent affecter sa maintenabilité soient analysées, y compris
– les conditions de fonctionnement et de maintenance, telles que durée et type de mission, l'identification des cycles et charges imposées au produit pendant le temps prévu d'utilisation;
– il convient que les contraintes imposées par la politique de maintenance, le niveau de qualification du personnel, etc soient identifiées et, lorsque cela est nécessaire, des modifications soient recommandées;
– il convient que chaque interprétation des spécifications de besoins faisant l'objet d'un accord soit documentée formellement et jointe aux spécifications.
Gestion de projet
Gestion de la maintenabilité
A maintenance management plan should be developed by the supplier/designer to ensure that maintainability is considered at every relevant stage of the design process This plan must involve all stakeholders associated with the project, including management It should provide a detailed description of how the maintenance efforts will be managed and outline the supervision of subcontractors.
The plan must consider the requirements of the maintainability policy and how it is likely to be implemented Therefore, it is essential to consult the client whenever necessary.
Il convient que le plan identifie
– les responsables qui doivent assurer que le produit est réalisé de manière satisfaisante en ce qui concerne la maintenabilité;
– leurs responsabilités dans le programme de maintenabilité;
– les procộdures pour maợtriser le programme.
Il convient que le plan conduise à la préparation d'un programme de maintenabilité pour la conception du projet.
Plans du programme de maintenabilité
Il convient que le programme détaille les tâches du programme de maintenabilité qui doivent être réalisées Il convient qu’il comporte pour chaque tâche les informations suivantes:
– une description détaillée de la tâche, incluant les objectifs spécifiques qui doivent être atteints à chaque étape du programme et les heures de main d'œuvre nécessaires;
The task steps should align with the overall plan, ensuring that there are enough stages to achieve a satisfactory mastery of the task Each step must be clearly described, detailing the information required for an effective review.
– le but de la tâche et les résultats attendus, incluant les méthodes de surveillance en fonctionnement, l'évaluation, les rapports et les actions appropriées pour corriger les problèmes;
– les moyens de communication entre différents fournisseurs ou sous-traitants;
– l'identification des problèmes auxquels on peut s’attendre à partir d'une connaissance préalable de la tâche et les actions proposées pour les résoudre.
Il convient qu’un tableau de correspondances soit fourni, et qu’il présente les relations entre les tâches du programme et
– les normes générales applicables, par exemple la CEI 60300-1 et la CEI 60300-2;
– les politiques et les normes du fournisseur;
– l'estimation des heures de main d'œuvre.
Gestion des décisions de projet
Il convient que des jalons et des points de contrôle soient établis pour chaque étape du programme.
It is essential to establish procedures and criteria to ensure satisfactory progress towards meeting maintainability requirements at each milestone or checkpoint.
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A maintainability management plan is essential for suppliers and designers to integrate maintainability into every stage of the design process This plan should engage all project stakeholders, including management, and outline the management of maintainability efforts, as well as the oversight of second-level suppliers.
The plan should take account of the requirements of the maintainability policy and how these might be implemented The client should therefore be consulted whenever necessary.
– those responsible for ensuring that the product performs satisfactorily regarding maintainability;
– their responsibilities within the maintainability programme;
– the procedures for establishing control of the programme.
The plan should lead into the preparation of a maintainability programme for the project design.
The programme should detail the maintainability programme tasks which will have to be carried out It should include the following information for each task:
– a detailed description of the task, including the specific objectives which have to be met at each stage of the programme and the man-hours involved;
The task is divided into several stages, each designed to provide adequate control over the overall plan It is essential that the number of stages is sufficient to ensure effective oversight Each stage must be clearly outlined, detailing the information that will be available for review.
– the purpose of the task and the expected results, including the methods for monitoring, assessing, reporting and taking appropriate action to correct problems;
– the lines of communication between different suppliers or subcontractors;
– identification of problems which may be expected from a prior knowledge of the task and the actions proposed for their solution.
A cross-index should be provided, which shows the relationships between programme tasks and
– applicable general standards, for example IEC 60300-1 and IEC 60300-2;
Milestones and checkpoints should be established for each stage of the programme.
Procedures and criteria should be produced which will ensure that satisfactory progress towards meeting maintainability requirements has been made at each milestone or checkpoint.
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Gestion de la configuration
To effectively manage product modifications and maintenance logistics throughout each phase of the lifecycle, it is essential to establish a configuration management system This system should implement a systematic process to control, monitor, and document changes to the product and its maintenance logistics.
La maợtrise de la configuration est approfondie en 6.10.2.
Conception en vue de la maintenabilité
Conception de la maintenabilité
High maintainability performance refers to a product that is easy to maintain and repair while requiring minimal maintenance Achieving high maintainability involves design approaches such as implementing automatic maintenance techniques, integrated test equipment (ITE), and automatic restarts during software-induced failures, along with modular design and quick disconnections.
It is essential to derive and periodically review detailed design criteria for maintainability based on the specified product requirements These criteria should outline methods and techniques aimed at minimizing maintenance challenges.
– les pannes qu'il peut être difficile ou cỏteux de corriger une fois que le produit est terminé;
– la fréquence des activités de maintenance périodiques imposées par la conception du produit;
– la contribution spécifique du produit au temps d'indisponibilité;
– les cỏts de logistique de maintenance résultant de la conception du produit;
– la qualification requise du personnel de maintenance;
– les erreurs potentielles de maintenance;
– les difficultés d'accès pour la maintenance et le remplacement;
– l'utilisation d'équipements et d'outils spéciaux;
– les menaces pour la santé résultant de l'utilisation de produits toxiques ou radioactifs.
Design activities should be guided by features that ensure desired maintainability performance, in accordance with a given maintenance policy This involves understanding the relationships between various factors that influence maintainability outcomes.
– systèmes, sous-systèmes et matériels;
Il convient de procéder, si nécessaire, à une analyse de maintenance basée sur la fiabilité
This will enable the integration of appropriate conditional operational monitoring into the design, ensuring that monitoring tasks can be performed in the most efficient manner.
It is essential to identify critical equipment for maintainability based on specified criteria and definitions of criticality A program should be established to manage and control this critical equipment throughout all phases, from design and development to manufacturing and installation.
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As it may be necessary to introduce changes to the product and its maintenance support during any phase of the life cycle, a configuration management system should be established.
This should institute a systematic process for controlling, monitoring and documenting changes to the product and its maintenance support.
Configuration control is further discussed in 6.10.2.
High maintainability ensures that a product is easy to maintain and repair while minimizing maintenance needs This is accomplished through design strategies that include the use of automatic maintenance techniques, built-in test equipment (BITE), automatic restarts for software-induced failures, modular design, and quick disconnect fasteners.
The derivation and periodic review of detailed maintainability design criteria should be obtained from requirements specified for the product They should, for example, describe methods and techniques to minimize
– faults which may be difficult or costly to correct once the product is completed;
– frequency of scheduled maintenance activities dictated by the product design;
– product specific contribution to down time;
– maintenance support costs dictated by the product design;
– difficulties of access for maintenance and replacement;
– the use of special tools and equipment;
– threats to health by use of toxic or radioactive materials.
Design activities should be guided by the use of features to achieve the desired maintainability performance under the given maintenance policy, i.e the inter-relationship between
A reliability-centered maintenance analysis should be conducted when relevant, allowing for the integration of effective condition monitoring into the design, thereby optimizing monitoring tasks.
Identifying maintainability critical items is essential and should be based on defined criticality criteria It is important to establish a program for the management and special handling of these critical items throughout all phases, including design, development, manufacturing, and installation.
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When redesigning an existing product, it is essential to thoroughly document its maintainability performance and address all known issues during the development phase.
Compromis de fiabilité et de maintenabilité
It may not always be feasible to achieve a high level of reliability, high maintainability, and low maintenance simultaneously In such situations, a compromise solution can be developed, which involves balancing reliability and maintainability.
Achieving a high level of reliability is possible through effective design techniques that prevent both manifest and latent failures (failure avoidance) or mitigate their effects (fault tolerance) This is crucial for safety and operational reasons in certain products However, the critical parameter is often the availability of a component, which depends on reliability, maintainability, and maintenance logistical support.
It is essential that compromise analysis considers the impacts on availability, particularly in terms of potential life cycle costs (LCC) and possible operational penalties associated with accepting a lower level of reliability or maintainability The initial costs of implementing a design that values these two parameters may not be feasible Therefore, higher levels of maintenance logistical support may need to be taken into account during the analysis.
Conception en vue de faciliter la logistique de maintenance
Maintenance logistics, encompassing management resources and activities, is essential both during the installation and commissioning of a product and throughout its operational life.
The required logistics support resources will be determined by the product design, the established maintenance policy, and the necessary procedures, tools, testing equipment, documentation, training programs, and arrangements to support this policy.
De plus, il convient de prendre en considération l'identification et la préparation
The article outlines the essential procedures and resources required for the collection, analysis, and evaluation of failures, maintenance reports, and data related to reliability, maintainability, and maintenance logistics.
– des procédures et l'identification des ressources nécessaires à la mise en œuvre des demandes de modification et des transformations du produit;
– de l'identification de l'intervalle de temps pendant lequel le produit sera soutenu par le fournisseur et par le client respectivement.
When design work is based on an existing product, it is essential to reassess the maintenance logistics of that product and address any known issues.
Plus de détails peuvent être trouvés dans la CEI 60706-4.
Testabilité
The reliability and maintainability performance of a product are significantly affected by both internal and external resources that enable effective monitoring during operation, as well as the detection and localization of failures and any degradation in the product's characteristics.
The section of the specifications related to testability requirements, including test functions and procedures as well as the accuracy of tests at each product level, should effectively guide the design activities.
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When the design work is based on an existing product, that product's maintainability performance should be clearly documented and any known problems considered during the development phase.
6.4.2 Reliability and maintainability trade off
Achieving a balance of high reliability, high maintainability, and low maintenance is often challenging In these situations, a compromise solution can be created, necessitating a trade-off between reliability and maintainability.
High reliability performance may be obtained by good design techniques which prevent failures from occurring, whether patent or latent (fault avoidance), or eliminate their effects
Fault tolerance is crucial for ensuring safety and operational efficiency in various products However, the key factor for most items is their availability, which depends on reliability, maintainability, and maintenance support.
A trade-off analysis is essential to evaluate the impact on availability concerning Life Cycle Cost (LCC) and potential operational penalties when opting for reduced reliability or maintainability The initial investment required for a design that maximizes both reliability and maintainability may not be feasible Additionally, the analysis should consider the implications of enhanced maintenance support.
Maintenance support in the form of resources and management activities will be required during the installation or commissioning of the product, as well as during its operational life.
The necessary support resources will be dictated by the product design, the established maintenance policy, and the essential procedures, tools, test equipment, documentation, training programs, and facilities needed to uphold that policy.
Consideration should, in addition, be given to the identification and preparation of
– procedures and resource needs for collection, analysis and evaluation of fault and maintenance reports and data related to reliability, maintainability and maintenance support;
– procedures and identification of resources needed for handling of modification requests and product changes;
– identification of the time interval during which the product will be supported by the supplier and by the customer, respectively.
When the design work is based on an existing product, that product's maintenance support conditions should be reviewed and known problems considered.
More detailed guidance may be found in IEC 60706-4.
The reliability and maintainability of a product are significantly affected by both internal and external systems that monitor, detect, and localize faults, as well as any degradation in the product's characteristics.
The part of the specification addressing the testability requirements (test functions and procedures, test accuracy of each level of the product, etc.) should guide these design activities.
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When designing based on an existing product, it is essential to clearly document the testability features of that product and to address any known issues during the development phase.
Plus de détails peuvent être trouvés dans la CEI 60706-5.