The analysis was based on operational tests done on a selected sample of locomotives run by the polish rail company pkp cargo s. 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. Analysis of reliability, availability and maintainability ram of sm48 diesel locomotive maciej szkoda1 summary. Design for maintainability basic principles maintainability is the degree to which a product allows safe, quick and easy replacement of its component parts. Reliability is the probability that an engineering system will perform its intended function satisfactorily from the viewpoint of the customer for its intended life. In maintainability, the normal distribution applies to relatively straightforward maintenance tasks and repair actions e. Maintainability in the system lifecycle the systems engineering plan has a major section devoted to integration of the engineering specialties into the design process. The measurement and track of maintainability are intended to help reduce or reverse a systems tendency toward code entropy or degraded integrity, and to indicate when it becomes cheaper andor less. Astm f2446042010 standard classification for hierarchy. Reliability, maintainability, and safety for engineers 1st. Maintainability is created during the design process. In this setting, internal attributes used to define these properties, are captured. Astm f2446 042010 standard classification for hierarchy of equipment identifiers and boundaries for reliability, availability, and maintainability ram performance data exchange. The maintainability index is calculated with certain formulae from linesofcode measures, mccabe measures and halstead complexity measures.
Maintainability is the degree to which a product allows safe, quick and easy replacement of its component parts. Where the content of the ebook requires a specific layout, or contains maths or other special characters, the ebook will be available in pdf pbk format. The study was targeted at the software quality attribute of. Us69047b1 availability, reliability or maintainability. Reliability, availability, maintainability, inspectability rami 1page summary availability is a primary metric for an attractive power plant, directly affecting the cost of electricity. To open a pdf file in your browser, click the filename. Reliability, maintainability, and availability rma analysis. An introduction to total productive maintenance tpm. Each of these parameters has a very precise definition that may have slightly. Maintainability is itself a measure of the ease to modify code, higher maintainability means less time to make a change. Availability is defined as a percentage measure of the degree to which machinery and equipment is in an operable and committable state at the point in time when it is needed. Reliability, availability, maintainability, inspectability. Frb meetings and will be provided through the software failure database.
All bsi british standards available online in electronic and print formats. Put yourself in the place of the maintenance engineer, and try to design out any obstacles to easy maintenance. Maintainability is the ease with which a product can be maintained in order to isolate defects or their cause, correct defects or their cause, meet new requirements, make future maintenance easier, or cope with a changed environment. The monitoring system of claim 15, wherein the means for calculating a figure of merit fom includes instructions executable on the monitoring system to weight contributions to an availability, reliability or maintainability index in accordance with the associated business impact of each event on the monitored systems or subsystems. Common information exchange format using xml simplifies exchange of tests, results, diagnostics and maintenance information results saved in common format and may be used in traditional paper or net centric digital scenario as required. This page provides access to us department of defense directives, handbooks and standards related to reliability practices. Maintainability is a probability measure that a product will be maintained or restored to the specified function for a specified period of time at any specific level of repair conditions. Each technique follows a specific format so users can easily extract necessary information. Reliability, availability, and maintainability article.
The format of these ac knowledgment in building an operating m odules should be standardized so that code can system. 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. Characteristic of design and installation which determines the probability that a failed equipment, machine, or system can be restored to its normal operable state within a given timeframe. Ram is a subset of rams which also includes safety. Most vitalsource ebooks are available in a reflowable epub format which allows you to resize text to suit you and enables other accessibility features. Preventative maintenance, for example replacing engine spark plugs every 30,000. Nonfunctional requirement examples requirements quest. May 20 learn how and when to remove this template message. The purpose is to meet the plant ram performance goals by identifying program requirements that support effective reliability processes in design, construction and commissioning, and operations. Maintenance task times of this nature are usually normally distributed, producing a probability density function. Reliability, availability, maintainability, and cost. Introduction to maintainability university of tennessee. The goal of the tpm program is to markedly increase production while, at the same time, increasing employee morale and job satisfaction. From the definition, it is evident that any form of availability anal ysis is timerelated.
For example, increased efficiency may be achieved at. Pdf how to effectively define and measure maintainability. The input format is a repair time, followed by a single space, followed by the number of observations frequency. 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. The study was targeted at the software quality attribute of maintainability as opposed to the process of software maintenance.
This article describes a model format for incorporating the best practices for. The need for maintenance is predicated on actual or impending failure ideally, maintenance is performed to keep equipment and systems running eficiently for at least design life of the components. Maintainability and flexibility at the software level are of predominant importance to drive innovation at the business process level. Maintainability is defined as the ease with which changes can be made to a software system. The guidebook, presented in two volumes, provides a methodology for applying reliability, availability and maintainability ram evaluation techniques to the special needs of a nuclear waste repository. Maintainability is the measure of ability to successfully repair or fix the product after manufacturing, usually in the field, and over time. Recommended techniques for effective maintainability. The 14 categories presented in the book, along with 5 additional categories, are explored in the ondemand course, nonfunctional requirements. Maintainability definition of maintainability by the.
Maintainability definition, to keep in existence or continuance. The model file describes all of the transitions between states in the markov model and their corresponding rates in the format required for input to the sure program. 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. Prepared by the office of the secretary of defense in. The sum of direct maintenance labor hours divided by the total number of preventive and corrective maintenance actions during a stated period of time. Reliability represented here by the mean time between failures, mtbf and maintainability represented. Safety management in design is addressed in procedure epd 0008. This definition includes operable and committable factors that are. For example, a more maintainable product lowers maintenance time and. Where the content of the ebook requires a specific layout, or contains maths or other special characters, the ebook will be available in pdf pbk format, which cannot be reflowed. Dod guide for achieving reliability, availability, and maintainability systems engineering for mission success august 3, 2005 foreword i ram guide.
Coding standards are a way to achieve high maintainability and are developed as a. Data from testing is often expensive, resulting in small sample sizes. Early in the definition phase, expected changes should be. Maintainability is a probability measure that a product will be. This section sets forth basic definitions, briefly describes probability distributions. Nonfunctional requirements are vital to the success of software systems. These documents can be downloaded or viewed and printed in.
The software metrics study was initiated to propose metrics of the maintainability of the software produced by the mdsf project. Reliability, availability, maintainability, inspectability rami. Military directives, handbooks and standards related to reliability. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. The appropriate pdf for the ttf can be determined using the timesto. Facilities management for building maintainability. Maintainability design checklist the following is a maintainability design checklist for coal mining equipment. The key performance indicators for the maintenance organization may include key performance indicators for other areas of accountability such as health and safety performance, employee performance management, training and development, etc. Supports maintainability group definition for procedure 5a including fault isolation methodology and reassembly parameters export data from windchill maintainability into an milstd88 2b lsar compatible format. Sep 03, 2011 in maintainability, the normal distribution applies to relatively straightforward maintenance tasks and repair actions e. The paper presents the results of a ram analysis of the sm48 diesel locomotive. The data format shall be the same as the current hardware data format. Maintenance task times of this nature are usually normally distributed, producing a probability density function given by. Fmeca is performed prior to any failure actually occurring and analyzes risk to take action and thus provide an opportunity to reduce the possibility of failure.
Mean time to repair mttr is the most common measure of maintainability. 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. Maintainability are the relative costs of fixing, updating, extending, operating and servicing an entity over its lifetime. It is apparent,from the definition of maintainability, that the ability and need to. Pdf buildability and maintainability in final account.
Software design for maintainability, page 3 of 6 technique dfe6 page dfe25 modul es may be built. Table of contents chapter 1 reliability, availability, maintainability, and the department of defense 1. The frb shall verify the functions involved and whether or not failures count towards chargeable down time. Gb244682009specification for definition and measurement of semiconductor equipment reliability,availability and maintainabilityram text of document is in ch. Reliability, availability and maintainability ram epd 0009 introduction this procedure applies to the management of reliability, availability and maintainability ram of the railway system. A definition of maintainability with a few examples. Dod reliability availability and maintainability acqnotes. How to effectively define and measure maintainability. In engineering, maintainability is the ease with which a product can be maintained in order to. Availability and maintainability in engineering design. Logistic support analysis lsa process as it pertains to milstd881, logistic support analysis and milstd882, dod requirements for a logistic support analysis record and their associated interfacing standards and documents.
A factor is a top level expression of software status for management reporting. Reliability, maintainability, and availability rma. These changes may be necessary for the correction of faults, adaptation of the system to a meet a. Reliability, availability, and maintainability sebok.
Pdf maintainability myth causes performance problems in smp. Pdf maintainability and flexibility at the software level are of predominant importance to drive innovation at the business process level. Yes, i want a free nonfunctional requirement categories job aid. Atml standards and integration with maintainability minimalv2. Maintainable software, modular design, object oriented design. Standardizing availability definition plant maintenance. Reliability availability and maintainability considerations. Maintainability depends on the product design and the technical level of repair personnel, the repair process, and the repair facilities. An example network for native machine code generation. Citation format astm f244604, standard classification for hierarchy of equipment identifiers and boundaries for reliability, availability, and maintainability ram performance data exchange, astm international, west conshohocken, pa, 2004.
Reliability, availability, and maintainability of equipment. The first page of each technique is a summary of the information contained, and the rest of the technique contains the specific detail of the process. This handbook is to be used in concurrent with milstd881 and milstd882. Reliability, availability, maintainability, and cost rationale report manual. The portable document format pdf 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. Military directives, handbooks and standards related to. This document supplements departmental manuals, directives, military standards. Astm f2446 04 standard classification for hierarchy of. Total productive maintenance tpm is a maintenance program, which involves a newly defined concept for maintaining plants and equipment. Logistic support analysis lsa process as it pertains to milstd881, logistic support analysis and milstd882, dod requirements for a logistic support analysis record and their associated. As an alternate input method, two columns from excel may be pasted into the box above repair time, no.
Reliability, maintainability, and availability ram are three system attributes that. For manufacturing entities, many of the maintainability requirements. 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. As noted earlier, operational testing is intended to assess the effectiveness and. The key performance indicators for the maintenance organization may include key performance indicators for other areas of accountability.
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