Pdf how to effectively define and measure maintainability. Scope is defined based on the analysis goal, time available, and customer requirements. It can be used in reliability prediction to calculate the availability of. This site provides reliabilityrelated handbooksstandards only. Availability is the probability that the system is operating satisfactorily at any time, and it depends on the reliability and the maintainability. Maintenance laborhours per month maintenance laborhours per maintenance action maintenance frequency factors meantime between maintenance mtbm unscheduled corrective and scheduled preventive meantime between replacement mtbr 10 maintainability function definition.
Reliability, availability, and maintainability sebok. Maintainability is a component of a more general concept, software quality, which is described in terms of a hierachy see figure 1 em87 of factors, criteria and metrics. Reliability, availability, and maintainability ram analysis. Reliability, availability, and maintainability the mitre. Tutorials in maintenance management for reliability. In most cases this period encompasses the normal distribution of design life failures. Over time, this has come to include multiple wordings that describe various costeffective practices to keep equipment operational. Andrew taylor bsc ma frsa art and engineering in product design. Maintainability is a requirement of the cei and swci specifications. Pdf a model of maintainability suggestion for future research. The technical meaning of maintenance involves functional checks, servicing, repairing or replacing of necessary devices, equipment, machinery, building infrastructure, and supporting utilities in industrial, business, governmental, and residential installations.
Department of transportation federal aviation administration reliability, maintainability, and availability rma handbook may 30, 2014 faa rmahdbk006b federal aviation administration 800 independence avenue, sw washington, dc 20591. This means there is a definite need for the maintainability, maintenance, and. Maintainability definition, to keep in existence or continuance. Reliability, maintainability, and availability rma handbook. Reliability, maintainability, and availability rma analysis. Availability is the probability that an item will be able to function i. This is a very important parameter as the system is subjected to changes throughout the software life cycle. Measuring software maintainability is nontrivial and there exists no single metric to measure it accurately. Pdf maintainability is an important character which is given by product design process. Maintainability definition of maintainability by medical.
Additionally, the ram attributes impact the ability to perform the intended mission and affect overall mission success. Software that is written without maintainability in mind requires about four times as much effort to maintain than it did to develop. Based on the definition of failure and quality, we can now in a position to define the two most. The mission of femp is to facilitate the federal governments implementation of sound, cost effective energy management and investment practices to enhance the nations energy security and.
Maintainability is defined as the ease with which changes can be made to a software system. A pdf file is a portable document format file, developed by adobe systems. The aim behind effective maintenance is to minimise the mean downtime mdt and the related costs. These changes may be necessary for the correction of faults, adaptation of the system to a meet a new requirement, addition of new functionality, removal of existing functionality or corrected when errors or deficiencies occur and can be perfected, adapted or action taken to reduce further. The ram program must interface with logistic support planning and execution to ensure that each complements the other. Introduction to ram analysis we have discussed many approaches to working with failure data and making decisions based on qualitative or quantitative reliability engineering methodologies. Introduction to maintainability university of tennessee. Developing maintainable software software sustainability. Mean time to repair mttr is the most common measure of maintainability. For manufacturing entities, many of the maintainability requirements are born out, at least in part, by the manufacturing and assembly environment of.
Pdf file or convert a pdf file to docx, jpg, or other file format. General guidelines on the analysis of reliability, availability and maintainability are provided in. The purpose of the gemini reliability and maintainability plan is to help make tradeoffs and identify candidates for more detailed reliability engineering and redesign, or more extensive, online predictive diagnostics, preventive maintenance and spares stocking. These documents can be downloaded or viewed and printed in. This kind of maintainability prediction analyzes how long repairs and maintenance tasks will take in the event of a system failure. An entity with relatively low costs in these areas is considered maintainable whereas an entity with high costs may be considered unmaintainable or high maintenance. Maintainability is itself a measure of the ease to modify code, higher maintainability means less time to make a change. Maintainability is the probability that maintenance of the system will retain the system in, or restore it to, a specified condition within a given time period. Mission objectives include safety, mission success and sustainability criteria. Specification for definition and measurement of equipment reliability, availability, and maintainability ram this standard was technically approved by the global metrics committee and is the direct responsibility of the north american metrics committee. A method that requires more than 7 statements is simply doing too much or has too many responsibilities. Basic principles maintainability is the degree to which a product allows safe, quick and easy replacement of its component parts. However, existing definitions of maintainability, such as the halstead volume, mccabes cyclomatic complexity or the sei maintainability index.
The definitions of availability are qualitative in distinction, and indicate signifi cant differences in. Quantitatively, the probability that an item will be restored to specified. Reliability, maintainability, and availability ram are three system attributes. Maintainability is a multifaceted quality attribute each of the facets must be analyzed to objectively measure it. Reliability is the probability that an engineering system will perform its intended function satisfactorily from the viewpoint of the customer for its intended life under specified environmental and operating conditions. Pdf format is a file format developed by adobe in the 1990s to present documents, including text formatting and images, in a manner independent of application software, hardware, and operating systems. Looking for online definition of maintainability or what maintainability stands for. To save a file, rightclick the filename and select save target as or the equivalent for your web browser from the shortcut menu. It also requires the human mind to analyze the exact statements to understand what the code is doing. As noted earlier, operational testing is intended to assess the effectiveness and. Standardizing availability definition plant maintenance. For manufacturing entities, many of the maintainability requirements are born out, at least in part, by the manufacturing and assembly environment of the customer organization.
Many methodologies are proposed so far to estimate maintainability of software. It is the average time required to perform corrective maintenance on all of the removable items in a product or system. In engineering, maintainability is the ease with which a product can be maintained in order to. Reliability, availability, maintainability, and cost rationale report manual. To open a pdf file in your browser, click the filename. Reliability, availability, and maintainability analysis pdf. Through the utilization of various nondestructive testing and measuring techniques, predictive maintenance determines equipment status before a breakdown occurs. May 20 learn how and when to remove this template message in engineering, maintainability is the ease with which a. Finally, the authors would like to extend their appreciation to pnnls document production team dave payson and elaine schneider for the conscientious, teamoriented, and high quality assistance they brought to this version of the document. This document is one of a set of standards developed solely and specifically for use on transport assets as defined in the asset. Pdf maintainability, maintenance, and reliability for engineers. Maintainability assessment is an essential aspect of software development.
Pdf a model of maintainability suggestion for future. Chapter 8 reliablity, maintainability and availablity. Measuring software maintainability quandary peak research. How to effectively define and measure maintainability. Please help to improve this article by introducing more precise citations. Availability and maintainability in engineering design. Chapter 4 reliability, availability, and maintainability analysis 4. Predictive maintenance is the complement of preventive maintenance.
Handbook of reliability, availability, maintainability and safety in. Maintainability maintenance is the activity of modifying a software product after initial delivery. Maintainability is determined by the equipments operating and repair effectiveness. Coding standards are a way to achieve high maintainability and are developed as a result of previous experiences, they arent universal and are dependent on developer preferences. The standard definition of reliability is the probability of zero.
Operational availability is the ratio of the system uptime and total time. This page provides the answers to questions that have been asked of the nrc staff concerning the. A lack of maintainability will be evident as high product maintenance costs, long outof service times, and possible. Reliability, availability, and maintainability article. The associations ability to conduct routine maintenance, to handle emergency repairs, and to plan and carry out longterm improvements in the condition of the building will be key factors in whether or not your association succeeds. Department of energys federal energy management program femp. Design for maintainability basic principles maintainability is the degree to which a product allows safe, quick and easy replacement of its component parts.
For this reason, many applications are replaced simply because the overhead to modify them becomes prohibitive. Maintainability and flexibility at the software level are of predominant importance to drive innovation at the business process level. As discussed in previous sections, systems engineering activities can be directed to designing and manufacturing reliability and maintainability into the system, but availability is the function of this inherent reliability and maintainability as well as the systems supportability and producibility. Current edition approved by the north american regional. This white paper is an informal document approved at the office manager level. Aug 18, 2018 the ease with which something can be maintained. Misra, maintenance engineering and maintainability an introduction, chapter 46, handbook of performability engineering, springer, 2008. Maintenance rule frequently asked questions faqs this page was last updated july 19, 2000 by donnie ashley and will not be updated. Focus on operability and maintainability for project success. These parameters include mean time to repair mtr, mean time between failures mtbf, scheduled maintenance frequencies, maintenance manhours per. Maintainability what does maintainability stand for. Pdf product maintainability design method and support tool. Reliability, maintainability, and availability rma analysis for the ecs project white paper february 2002 prepared under contract nas560000 responsible author william wyman s 21102 william wyman, ils manager date eosdis core system project responsible office valecia maclin s 21102 valecia maclin, director systems engineering date. This article includes a list of references, related reading or external links, but its sources remain unclear because it lacks inline citations.
Reliability, availability, maintainability, and cost. Maintainability article about maintainability by the free. Maintainability definition of maintainability by the. Introduction to maintainability the concept of maintainability encompasses. However, existing definitions of maintainability, such as the halstead volume, mccabes cyclomatic complexity or the sei maintainability index provide a very poor understanding of what maintainability is how it. If the scope is poorly defined, the time needed to perform analysis will be higher and the final results will probably not be sufficient for the customer. Ram requirements definition is as challenging but as essential to development success as is the definition of general functional requirements.
Following the opinion that maintainability is the set of attributes that bear on the effort needed to make specified modifications16, we describe maintainability according to this approach as a function of directly measurable attributesa. Its objectives are to define the concept of maintainability, to describe the factors influencing it and to define criteria by which maintainability can be quantitatively. Maintainability analysis of mechanical systems of electric cable shovels 269 determining best fit theor etical pr obability distributions once the data are identified to be free of correlations and trends, the time independent distribution model gives the best estimate of maintainability function. In some cases, maintainability involves a system of continuous improvement learning. Facilities management for building maintainability. Reliability, availability, and maintainability ram or rma are system design attributes that have significant impacts on the sustainment or total life cycle costs lcc of a developed system. With predictive devices currently available, it is incumbent upon. Reliability, maintainability, and availability rma. Maintenance concepts, spare and repair parts provisioning, and allocation of maintenance resources must support the system readiness objective. Maintainability are the relative costs of fixing, updating, extending, operating and servicing an entity over its lifetime. For each there is a set of criteria that enables a practitioner to assess whether a system has achieved that particular principle. The panel has undertaken an inquiry into current policies and statistical practices in the area of system reliability, availability, and maintainability as related to operational testing in the dod acquisition process.
The ideas expressed in this white paper are valid until the end of the ecs contract. The term maintainability corresponds to the ability to update or modify the system under test. The wearout period is characterized by a rapid increasing failure rate with time. Mean time to repair also factors in other reliability and maintainability predictions and analyses. An overview of maintenance and its management 250 kb pdf file the context of applying maintenance practices 500 kb pdf file the principal causes of failure in machinery 300 kb pdf file detection of the need for conducting maintenance 750 kb pdf file language of machine vibration measurement and analysis 1. Pdf maintainability measurement in object oriented paradigm. Instead of announcing its already reserved judgement, the court provided petitioner riaz hanif rahi an opportunity to file additional arguments by today friday and said the decision on maintainability would be announced on monday after examining the written arguments filed by the petitioner. Specified or assigned quantitative and qualitative features of an equipment, machine, or system that ensure it meets defined maintainability objectives or requirements. A factor is a top level expression of software status for management reporting. Developing maintainable software helps reduce technical debt. Information and translations of maintainability in the most comprehensive dictionary definitions resource on the web. Prepared by the office of the secretary of defense in.
Faa reliability, maintainability, and availability rma handbook faa rmahdbk006b i u. Maintainability analysis of mechanical systems of electric. The four essential principles underlying reliable systems are availability, security, integrity and maintainability. In engineering, maintainability is defined as a characteristic of equipment design and installation expressed in terms of ease and economy of maintenance, availability of the equipment, safety and accuracy in the performance of maintenance actions blanchard and lowery, 1969.
A model of maintainability suggestion for future research conference paper pdf available january 2006 with 298 reads how we measure reads. An operational measure of effectiveness a characteristic of design an engineering spe cialty that supports design a cost driver a planned activ ity in each stage of product lifecycle 2 introduction cont. An overview on reliability, availability, maintainability and. Maintainability is about the duration of repair outages. While maintainability is important as a factor of availability, it also merits substantial consideration as an individual system characteristic. Emergency maintenance maintenance activities that are unscheduled repair, to include call outs, to correct an emergency need to prevent injury, loss of property, or return asset to service. Maintainability article about maintainability by the. Needless to say, maintainability, maintenance, and reliability of such systems. Maintainability is the ease with which a software product can be modified. Break it down in multiple small and focused methods with.
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