Glossary of Reliability Terms and Definitions for maintenance of in- service assets

2nd Edition 2013 Mark Ho and Melinda Hodkiewicz University of Western Australia Perth, Australia 6009 And CRC Mining, Australia

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Contents 1 Executive Summary ...... 8 2 Reference Sources ...... 8 3 General Definitions ...... 10 3.1 asset ...... 10 3.2 asset, critical...... 10 3.3 asset hierarchy ...... 10 3.4 asset management ...... 10 3.5 (asset management) objective ...... 10 3.6 (asset management) plan ...... 10 3.7 (asset management) policy ...... 10 3.8 asset management strategy ...... 10 3.9 asset management system ...... 10 3.10 components ...... 10 3.11 condition monitoring ...... 10 3.12 corrective action ...... 10 3.13 demand ...... 11 3.14 Dependability ...... 11 3.15 desired performance ...... 11 3.16 discard ...... 11 3.17 disposal ...... 11 3.18 environment...... 11 3.19 equipment class ...... 11 3.20 equipment data ...... 11 3.21 equipment unit ...... 11 3.22 error ...... 11 3.23 failure data ...... 11 3.24 function ...... 11 3.24.1 function, primary ...... 12 3.24.2 function, secondary ...... 12 3.25 functional failure ...... 12 3.26 inspection ...... 12

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3.27 item ...... 12 3.28 level of service ...... 12 3.29 life profile ...... 12 3.30 life units ...... 12 3.31 life cycle ...... 12 3.32 life cycle cost ...... 12 3.33 acquisition cost ...... 12 3.34 ownership cost ...... 12 3.35 maintainability ...... 13 3.36 maintainable item ...... 13 3.37 maintenance ...... 13 3.37.1 maintenance, breakdown ...... 13 3.37.2 maintenance, condition based...... 13 3.37.3 maintenance, corrective ...... 13 3.37.4 maintenance, opportunity ...... 13 3.37.5 maintenance, predictive ...... 13 3.37.6 maintenance, preventive ...... 13 3.37.7 maintenance, proactive ...... 13 3.37.8 maintenance, scheduled ...... 13 3.37.9 maintenance, unplanned ...... 13 3.37.10 maintenance, unscheduled ...... 13 3.38 maintenance action ...... 14 3.39 maintenance data ...... 14 3.40 maintenance impact ...... 14 3.41 maintenance plan ...... 14 3.42 maintenance policy ...... 14 3.43 maintenance programme ...... 14 3.44 maintenance record ...... 14 3.45 maintenance support ...... 14 3.46 maintenance support performance ...... 14 3.47 maintenance task ...... 14 3.48 modification ...... 14 3.49 not operating ...... 14 3.50 operable ...... 15

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3.51 operating context ...... 15 3.52 operating state ...... 15 3.53 operation ...... 15 3.54 organisation strategic plan ...... 15 3.55 owner ...... 15 3.56 predicted ...... 15 3.57 predictive action ...... 15 3.58 preventative action ...... 15 3.59 procedure ...... 15 3.60 process ...... 15 3.61 reassembly ...... 15 3.62 record ...... 15 3.63 redundancy ...... 16 3.64 redundancy, active ...... 16 3.65 redundancy, standby ...... 16 3.66 reliability ...... 16 3.67 reliability centred maintenance ...... 16 3.68 reliability growth ...... 16 3.69 reliability, generic data ...... 16 3.70 repair ...... 16 3.71 repairable item ...... 16 3.72 required function ...... 16 3.73 run to failure ...... 16 3.74 scheduled discard ...... 16 3.75 scheduled restoration ...... 16 3.76 servicing ...... 17 3.77 subsystem ...... 17 3.78 subunit ...... 17 3.79 subsystem ...... 17 3.80 system ...... 17 3.81 tag number ...... 17 3.82 taxonomy ...... 17 3.83 test ...... 17 4 Failure Definitions ...... 18

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4.1 criticality ...... 18 4.2 criticality analysis ...... 18 4.3 damage, accidental ...... 18 4.4 damage, secondary effects ...... 18 4.5 degradation ...... 18 4.6 failure ...... 18 4.6.1 failure, catastrophic ...... 18 4.6.2 failure, common cause ...... 18 4.6.3 failure, critical ...... 18 4.6.4 failure, degraded ...... 18 4.6.5 failure, dependant ...... 18 4.6.6 failure, evident ...... 18 4.6.7 failure, evident progression ...... 18 4.6.8 failure, hidden ...... 19 4.6.9 failure, hidden progression ...... 19 4.6.10 failure, incipient ...... 19 4.6.11 failure, independent ...... 19 4.6.12 failure, intermittent ...... 19 4.6.13 failure, non-critical ...... 19 4.6.14 failure, potential ...... 19 4.6.15 failure, single point ...... 19 4.6.16 failure, undetectable ...... 19 4.7 failure analysis...... 19 4.8 failure cause ...... 19 4.9 failure consequence ...... 19 4.10 failure data ...... 19 4.11 failure effect ...... 20 4.12 failure impact ...... 20 4.13 failure mechanism ...... 20 4.14 failure mode ...... 20 4.15 failure mode and effects analysis ...... 20 4.16 failure on demand ...... 20 4.17 failure rate ...... 20 4.18 fault ...... 20

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4.19 fault isolation ...... 20 4.20 fault localization ...... 20 4.21 infant mortality ...... 20 4.22 interchange ...... 20 4.23 local effect ...... 20 4.24 nonconformity ...... 21 4.25 severity ...... 21 5 Time Related Definitions...... 22 5.1 achieved ...... 22 5.2 availability ...... 22 5.2.1 availability, instantaneous ...... 22 5.2.2 availability, point ...... 22 5.2.3 availability, mean ...... 22 5.2.4 availability, average up time ...... 22 5.2.5 availability, steady state ...... 22 5.2.6 availability, inherent ...... 22 5.2.7 availability, achieved ...... 22 5.2.8 availability, operational ...... 22 5.3 age ...... 22 5.4 demonstrated ...... 23 5.5 direct man hours per maintenance action ...... 23 5.6 direct man hours per maintenance event ...... 23 5.7 life ...... 23 5.8 logistic delay ...... 23 5.9 maintenance man hours ...... 23 5.10 maintenance time ...... 23 5.11 mean maintenance time ...... 23 5.12 surveillance period ...... 23 5.13 Time ...... 23 5.13.1 time, active...... 23 5.13.2 time, active maintenance ...... 23 5.13.3 time, administrative ...... 24 5.13.4 time, alert ...... 24 5.13.5 time, checkout ...... 24

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5.13.6 time, delay ...... 24 5.13.7 time, down ...... 24 5.13.8 time, idle ...... 24 5.13.9 time, inactive...... 24 5.13.10 time, mission ...... 24 5.13.11 time, not operating ...... 24 5.13.12 time, operating ...... 24 5.13.13 time, reaction ...... 24 5.13.14 time, supply delay ...... 24 5.13.15 time, turn around ...... 24 5.14 uptime ...... 24 5.15 useful life ...... 25 5.16 utilization rate ...... 25 5.17 wearout ...... 25 6 General Definitions – Sources ...... 26 7 Failure Definitions – Sources...... 37 8 Time Definitions – Sources ...... 42

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1 Executive Summary

This document contains a glossary of reliability terms and definitions developed as part of a CRC Mining funded research project into the reliability of assets. The project was executed at the University of Western Australia in 2010 and the results published in 2013. The aim of this edition is to review and update the glossary.

To develop this glossary the first step was to conduct a review of national, international and industry standards and guidelines and develop a database from these sources specifically related to reliability, failure and time definitions. Following this a focus group was formed consisting of people involved with reliability in the mining. Focus group members brought a wide range of experience from within mining but also defence, oil and gas and infrastructure. A two stage process was used in which focus group members were first consulted individually in order to determine their preference for a specific definition from the database, the need for an alternate definition and the need for definitions for terms not covered. A number of definitions were developed for words commonly used in mining but not covered by formal definitions in the Standards referenced. Workshops were then held with all members of the focus group to resolve areas of differing preferences. The outcome of the workshops representing the preferred definition for each term are captured in Chapters 3, 4 and 5 of this glossary. The database of all the terms is in Chapters 6, 7 and 8.

Since the initial publication of this glossary in 2010, there has been the development of a new ISO Standard for Asset Management (ISO 55000). The database in this glossary has therefore been updated to include these new terms and where there has been a new definition from ISO 55000 FDIS that, in the judgement of the authors, will likely replace the definition selected by the focus group in 2010, the ISO 55000 definition has been used. This means that important terms like “asset” reflect the new definition in the ISO 55000 standard which is “something that has potential or actual value to an organisation” rather than a previous definition.

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2 Reference Sources

Table 1 lists the sources used to collect terms and definitions related to reliability, failure and time.

Standard Designation Standard Description ISO 55000 FDIS Asset Management – Overview, principles and terminology AS/NZS ISO 31000:2009 Risk Management – Principles and Guidelines Petroleum, petrochemical and natural gas industries — Collection and ISO 14224:2006 exchange of reliability and maintenance data for equipment Dependability Management Part 2. Guidance for Dependability AS IEC 60300.2 Programme Management

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Analysis techniques for system reliability - Procedure for failure mode AS IEC 60812-2008 and effects analysis (FMEA) MIL-STD-721C Definitions of Terms for Reliability and Maintainability Procedures for Performing a Failure Modes and Effects Criticality MIL-STD-1629A Analysis ISO 13372:2004(E) Condition monitoring and diagnostics of machines - Vocabulary IIMM V3.0 International Infrastructure Management Manual Version 3.0, 2006 PAS 55-1:2008 PAS 55 Asset Management Dependability management Part 3.11: Application guide—Reliability AS IEC 60300.3.11 centred maintenance AS IEC 60300.3.14— Dependability management Part 3.14: Application guide— 2005 Maintenance and maintenance support SAE JA 1012 A Guide to the Reliability-Centered Maintenance (RCM) Standard SAE JA 1011 Evaluation Criteria for Reliability Centered Maintenance Processes Elsayed, E., Reliability Engineering, Addison Wesley, Reading, MA, Elasayed, E 1996. British Standard: Glossary of terms used in quality assurance including BS4778 reliability and maintainability terms NASA 2002 Fault Tree Handbook with Aerospace Applications Functional safety of electrical/electronic/programmable electronic IEC 61508 Part 4 safety-related systems Part 4 Reliability Centered Maintenance Requirements for Naval Aircraft, MIL-STD 2173 Weapon Systems and Support Equipment International Electrotechnical Vocabulary (IEVJ, Chapter 191: IEC 50(191) Dependability and quality of service. AS/NZS 4536:1999 Life Cycle Costing - An Application Guide

Table 1: List of sources used in developing the terms and definitions.

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3 General Definitions 3.7 (asset management) policy 3.1 asset intentions and direction of an organization as something that has potential or actual value to formally expressed by its top management. an organization. Source: ISO 55000 FDIS Source: ISO 55000 FDIS 3.8 asset management strategy

3.2 asset, critical long term optimised approach to management of the assets, derived from, and consistent asset having the potential to significantly with, the organisational strategic plan and the impact on the achievement of the asset management policy. organization’s objectives Source: PAS 55 Asset Management Source: ISO 55000 FDIS

3.3 asset hierarchy 3.9 asset management system a framework for segmenting an asset base into management system for asset management appropriate classifications. The asset hierarchy that is there to establish the asset can be based on asset function; asset type or a management policy and asset management combination of the two. objectives. Source: New definition Source: ISO 55000 FDIS

3.10 components 3.4 asset management specific parts of an asset having independent coordinated activity of an organization to physical or functional identity. realize value from assets. Source: New definition

Source: ISO 55000 FDIS

3.11 condition monitoring 3.5 (asset management) continuous or periodic inspection, assessment, objective measurement and interpretation of the resultant data, to indicate the need for result to be achieved. Source: ISO 55000 FDIS maintenance action. Source: New definition

3.6 (asset management) plan 3.12 corrective action formulation of a programme of achieve an action to eliminate the cause of a objective. An asset management plan can be nonconformity and to prevent recurrence. for an asset, asset type, asset system or asset Source: ISO 55000 FDIS portfolio, service or product. Source: ISO 55000 FDIS

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3.13 demand Source: MIL-STD-721C

activation of the function (includes functional, operational and test activation). 3.19 equipment class Source: ISO 14224:2006

class of similar type of equipment units (e.g. all 3.14 Dependability pumps). Source: ISO 14224:2006

The collective term used to describe the availability performance and its influencing 3.20 equipment data factors: reliability performance, maintainability performance, and technical, operational and environmental maintenance support performance. parameters characterizing the design and use Source: AS IEC 60300.2 of an equipment unit. Source: ISO 14224:2006

3.15 desired performance 3.21 equipment unit the level of performance desired by the owner or user of a physical asset or system. specific equipment unit within an equipment Source: SAE JA 1012 class as defined by its boundary (e.g. one pump). 3.16 discard Source: ISO 14224:2006 removal from service of an item at a specified life limit. 3.22 error Not applicable for Reliability Centred Maintenance. discrepancy between a computed, observed or Source: AS IEC 60300.3.11 measured value or condition and the true, specified or theoretically correct value or condition. 3.17 disposal Source: ISO 14224:2006 activities necessary to dispose of 3.23 failure data decommissioned assets. Not applicable for Reliability Centred data characterizing the occurrence of a failure Maintenance event and conditions leading up to the event. Source: PAS 55 Asset Management Source: New definition

3.18 environment 3.24 function the aggregate of all external and internal what the owner or user of a physical asset or conditions (such as temperature, humidity, system wants it to do. radiation, magnetic and electrical fields, shock Source: SAE JA 1012 vibration) either natural or manmade, or self induced, that influences the form, performance, reliability or survival of an item.

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3.24.1 function, primary responsiveness, environmental acceptability and cost. the function(s) which constitute the main Source: IIMM V3.0 reason(s) why a physical asset or system is acquired by its owner or user. Source: SAE JA 1012 3.29 life profile

a time-phased description of the events and 3.24.2 function, secondary environments an item experiences from functions which a physical asset or system has manufacture to final expenditures or removal to fulfil apart from its primary function(s), such from the operational inventory, to include one as those needed to fulfil regulatory or more mission profiles. requirements and those which concern issues Source: MIL-STD-721C such as protection, control, containment, comfort, appearance, energy efficiency and 3.30 life units structural integrity. Source: SAE JA 1012 a measure of use duration applicable to the

item (e.g., operating hours, cycles, distance, 3.25 functional failure rounds fired, attempts to operate etc.). Source: MIL-STD-721C a state in which a physical asset or system is unable to perform a specific function to a 3.31 life cycle desired level of performance. Source: SAE JA 1012 the stages involved in the management of an

asset. 3.26 inspection Source: ISO 55000 FDIS

Examination of an item against a specific 3.32 life cycle cost standard. Source: AS IEC 60300.3.11 the sum of acquisition cost and ownership cost

of a product over its life cycle. 3.27 item Source: AS/NZS 4536:1999 any part, component, device, subsystem, 3.33 acquisition cost functional unit, equipment or system that can be individually considered. the initial cost to gain possession of the Source: ISO 14224:2006 completed product. Includes any research,

development, testing, evaluation costs, as well 3.28 level of service as the investment and installation cost. Source: AS/NZS 4536:1999 the defined service quality for a particular activity or service area against which service 3.34 ownership cost performance may be measured. Service levels usually relate to quality, quantity, reliability, summation of all operating expenses, maintenance, support and disposal costs

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borne by the owner or user of a complete 3.37.4 maintenance, opportunity product during its life cycle. maintenance of an item that is deferred or Source: AS/NZS 4536:1999 advanced in time when an unplanned opportunity becomes available. 3.35 maintainability Source: ISO 14224:2006 the measure of the ability of an item to be 3.37.5 maintenance, predictive retained in or restored to specified condition when maintenance is performed by personnel maintenance emphasising prediction of failure having specified skill levels, using prescribed and taking action based on the condition of the procedures and resources, at each prescribed equipment to prevent failure or degradation. level of maintenance and repair. Source: ISO 13372:2004(E)

Source: MIL-STD-721C 3.37.6 maintenance, preventive 3.36 maintainable item maintenance carried out at predetermined intervals or according to prescribed criteria item that constitutes a part or an assembly of and intended to reduce the probability of parts that is normally the lowest level in the failure or the degradation of the functioning of equipment hierarchy during maintenance. an item. Source: ISO 14224:2006 Source: AS IEC 60300.3.14—2005

3.37 maintenance 3.37.7 maintenance, proactive all actions necessary for retaining an item in or Term that encompasses condition based restoring it to a specified condition. maintenance, fixed interval maintenance and Source: MIL-STD-721C run to failure Source: ISO 13372:2004(E) 3.37.1 maintenance, breakdown maintenance performed after a machine has 3.37.8 maintenance, scheduled failed. all maintenance carried out in accordance with Source: ISO 13372:2004(E) an established schedule. Source: New definition 3.37.2 maintenance, condition based 3.37.9 maintenance, unplanned maintenance actions triggered by the all maintenance not carried out in accordance condition or performance of a function. with an established schedule Source: New definition Does not include breakdown maintenance.

Source: New definition 3.37.3 maintenance, corrective maintenance carried out after fault recognition 3.37.10 maintenance, and intended to put an item into a state in unscheduled which it can perform a required function. see maintenance, unplanned Source: ISO 14224:2006

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3.38 maintenance action an element of a maintenance event. One of 3.44 maintenance record more tasks (i.e., fault localization, fault all documentation related to a maintenance isolation, servicing and inspection) necessary activity. to retain an item in or restore it to a specified Source: New definition condition. Source: MIL-STD-721C 3.45 maintenance support

3.39 maintenance data resources required to maintain an item. Source: New definition proposed by CMERD data characterizing the maintenance action planned or done. Source: ISO 14224:2006 3.46 maintenance support performance

3.40 maintenance impact ability of a maintenance organisation, under given conditions, to provide upon demand, the impact of the maintenance on the plant or resources required to maintain an item, under equipment’s function(s). a given maintenance concept and guided by a Equipment function includes organisational maintenance policy. impact. Source: AS IEC 60300.3.14—2005 Source: ISO 14224:2006

3.47 maintenance task 3.41 maintenance plan action or set of actions required to achieve a collated information, policies and procedures desired outcome which restores an item to (or for the optimum maintenance of an asset, or maintains an item in) serviceable condition, group of assets. including inspection and determination of Source: IIMM V3.0 condition. Source: AS IEC 60300.3.11

3.42 maintenance policy 3.48 modification general approach to the provision of maintenance and maintenance support based combination of all technical and administrative on the objectives and policies of owners, users actions intended to change an item. and customers. Source: ISO 14224:2006

Source: AS IEC 60300.3.14—2005

3.49 not operating 3.43 maintenance programme the state wherein an item is able to function methods, procedures and resources required but is not required to function. for sustaining the support of an item Not to be confused with downtime throughout its lifecycle. Source: MIL-STD-721C

Source: AS IEC 60300.3.11

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3.50 operable 3.56 predicted the state of being able to perform the intended that which is expected at some future time, function. postulated on analysis of past experience and Source: MIL-STD-721C tests. Source: MIL-STD-721C

3.51 operating context 3.57 predictive action the circumstances in which a physical asset or system is expected to operate. action to monitor the condition of an asset and Source: SAE JA 1012 predict the need for preventative action or corrective action. 3.52 operating state Source: ISO 55000 FDIS state when an item is performing a required 3.58 preventative action function. Source: ISO 14224:2006 action to eliminate the cause of a potential non-conformity or other undesirable potential situation. 3.53 operation Source: ISO 55000 FDIS the active process of utilising an asset which 3.59 procedure will consume resources such as manpower, energy, chemicals and materials. Operation specified way of carrying out an activity or a costs are part of the lifecycle costs of an asset. process. Source: IIMM V3.0 Source: PAS 55 Asset Management

3.60 process 3.54 organisation strategic plan set of interrelated or interacting activities overall long term plan for the organisation that which transforms inputs into outputs. is derived from, and embodies, its vision, Source: ISO 55000 FDIS mission, values, business policies, stakeholder requirements, objectives and the management 3.61 reassembly of its risks. Source: PAS 55 Asset Management assembling the items that were removed during disassembly and closing the reassembled items. 3.55 owner Source: MIL-STD-721C a person or organisation that may either suffer or be held accountable for the consequences 3.62 record of a failure mode by virtue of ownership of the asset or system. Document stating results achieved or Source: SAE JA 1012 providing evidence of activities performed. Source: PAS 55 Asset Management

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3.63 redundancy Source: MIL-STD-721C the existence of more than one means for 3.69 reliability, generic data accomplishing a given function. Each means of reliability data covering families of similar accomplishing the function need not equipment. necessarily be identical. Source: ISO 14224:2006 Source: MIL-STD-721C

3.70 repair 3.64 redundancy, active see maintenance, corrective. that redundancy wherein redundant items are operating simultaneously. Source: New definition 3.71 repairable item

3.65 redundancy, standby an item which can be restored to perform all of its required functions by corrective that redundancy wherein the alternative maintenance. means of performing the function is not Source: MIL-STD-721C operating until it is activated upon failure of the primary means of performing the function. 3.72 required function Source: MIL-STD-721C function or combination of functions of an 3.66 reliability item that is considered necessary to provide a given service. the probability that an item can perform its Source: ISO 14224:2006 intended function for a specified interval under stated conditions. 3.73 run to failure Source: MIL-STD-721C maintenance approach that permits a specific 3.67 reliability centred failure mode to occur. Source: New definition maintenance systematic approach for identifying effective 3.74 scheduled discard and efficient maintenance tasks for items in accordance with a specific set of procedures a scheduled task that entails discarding an item and for establishing intervals between at or before a specified age limit regardless of maintenance tasks. its condition at the time. Source: New definition Source: SAE JA 1012

3.68 reliability growth 3.75 scheduled restoration the improvement in a reliability parameter a scheduled task that restores the capability of caused by the successful correction of an item at or before a specified interval (age deficiencies in item design or manufacture. limit), regardless of its condition at the time, to

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a level that provides a tolerable probability of 3.82 taxonomy survival to the end of another specified interval. systematic classification of items into generic Source: SAE JA 1012 groups based on factors possibly common to several of the items. Source: ISO 14224:2006 3.76 servicing 3.83 test the performance of any act needed to keep an item in operating condition, (i.e. Lubricating, experiment carried out in order to measure, fuelling, oiling, cleaning, etc.). quantify or classify a characteristic or a Source: New definition property of an item. Source: AS IEC 60300.3.11 3.77 subsystem a combination of sets, groups etc. Which performs an operational function within a system. (Example: Data processing subsystem, guidance subsystem). Source: MIL-STD-721C

3.78 subunit item or assembly of items within a system hierarchy that provides a specific function required for the system unit to achieve its intended performance. Source: New definition

3.79 subsystem a combination of sets or groups which perform an operational function within a system. Source: MIL-STD-721C

3.80 system set of assets that interact or are interrelated. Source: ISO 55000 FDIS

3.81 tag number number that can identify the physical location of equipment or an individual asset. Source: New definition

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4 Failure Definitions 4.6.1 failure, catastrophic sudden unexpected failure of a machine 4.1 criticality resulting in considerable damage to the a relative measure of the consequence of a machine and/or associated machines or failure mode and its frequency of occurrences. components. Source: MIL-STD-721C Source: ISO 13372:2004(E)

4.6.2 failure, common cause 4.2 criticality analysis failures of different items resulting from the a procedure by which each potential failure same direct cause, occurring within a relatively mode is ranked accordingly to the combined short time, where these failures are not influence of severity and probability of consequences of another. occurrence. Source: ISO 14224:2006 Source: MIL-STD-1629A

4.6.3 failure, critical 4.3 damage, accidental failure of an equipment unit that causes an immediate cessation of the ability to perform a physical deterioration of an item caused by required function. contact or impact with an object or equipment, Source: ISO 14224:2006 or maintenance. Source: AS IEC 60300.3.11 4.6.4 failure, degraded failure that does not cease the fundamental 4.4 damage, secondary effects function(s), but compromises one or several the result(s) or consequence(s) indirectly functions. caused by the interaction of a damage mode Source: ISO 14224:2006 with a system, subsystem or component thereof. 4.6.5 failure, dependant Source: MIL-STD-1629A failure which is caused by the failure of an

associated item(s). 4.5 degradation Source: MIL-STD-721C a gradual impairment of ability to perform. 4.6.6 failure, evident Source: MIL-STD-721C a failure mode whose effects become apparent to the operating crew under normal 4.6 failure circumstances if the failure mode occurs on its own. termination of the ability of an item to perform Source: SAE JA 1012 a required function. Source: ISO 14224:2006 4.6.7 failure, evident progression

The deterioration profile of an evident failure.

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Source: New definition Source: SAE JA 1012

4.6.8 failure, hidden 4.6.15 failure, single point a failure mode whose effects are not readily the failure of an item which would result in apparent. failure of the system and is not compensated Source: New definition for by redundancy or alternative operational procedure. 4.6.9 failure, hidden progression Source: MIL-STD-721C

The assumed deterioration profile of a hidden 4.6.16 failure, undetectable failure see hidden failure. Source: New definition

4.7 failure analysis 4.6.10 failure, incipient imperfection in the state or condition of an the logical systematic examination of an item, item so that a degraded or critical failure might its construction, application, and (or might not) eventually be the expected documentation to identify the failure mode result if corrective actions are not taken. and determine the failure mechanism and its Source: ISO 14224:2006 basic course. Source: New definition

4.6.11 failure, independent failure which occurs without being caused by 4.8 failure cause the failure of any other item. Source: MIL-STD-721C Circumstances associated with design, manufacture, installation, use and maintenance that have led to a failure. 4.6.12 failure, intermittent Source: ISO 14224:2006 failure for a limited period of time, followed by the item's recovery of its ability to-perform 4.9 failure consequence within specified limits without any remedial action. the way(s) in which the effects of a failure Source: MIL-STD-721C mode or a multiple failure matter (evidence of

failure, impact on safety, the environment, 4.6.13 failure, non-critical operational capability, direct and indirect failure of an equipment unit that does not repair costs). cause an immediate cessation of the ability to Source: SAE JA 1012 perform its required function. 4.10 failure data Source: ISO 14224:2006 4.6.14 failure, potential data characterizing the occurrence of a failure event. an identifiable condition that indicates that a Source: ISO 14224:2006 functional failure is either about to occur or is in the process of occurring.

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4.11 failure effect 4.18 fault what is observed when a failure mode occurs. state of an item characterized by inability to Source: New definition perform a required function, excluding the inability during preventative maintenance or other planned actions, or due to lack of 4.12 failure impact external resources. see failure consequence. Source: ISO 14224:2006

4.13 failure mechanism 4.19 fault isolation the physical, chemical, electrical, thermal or the process of determining the location of a other process which results in failure. fault to the extent necessary to effect repair. Source: ISO 14224:2006 Source: MIL-STD-721C

4.14 failure mode 4.20 fault localization the consequence of the mechanism through the process of determining the approximate which the failure occurs. I.e. short, open, location of the fault. fracture, excessive wear. Source: MIL-STD-721C Source: MIL-STD-721C

4.21 infant mortality 4.15 failure mode and effects analysis the relatively high conditional probability of failure during the period immediately after an a procedure by which each potential failure item enters service. Such failures are due to mode in a system is analysed to determine the defects in manufacturing not detected by results or effects thereof on the system and to quality control. classify each potential failure mode according Source: MIL-STD 2173 to its severity. Source: MIL-STD-721C 4.22 interchange

4.16 failure on demand removing the item to be replaced, and installing the replacement item. failure occurring unexpectedly when the item Source: MIL-STD-721C is required (e.g. stand-by emergency equipment). 4.23 local effect Source: New definition the consequence a failure mode has on the 4.17 failure rate operation, function or status of the specific item being analysed. The rate at which failures occur as a function of Source: MIL-STD-1629A usage. Source: New definition

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4.24 nonconformity non-fulfilment of a requirement. Source: ISO 55000 FDIS

4.25 severity the consequences of a failure mode. Severity considers the worst potential consequence of a failure, determined by the degree of injury, property damage, or system damage that could ultimately occur. Source: MIL-STD-1629A

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5 Time Related Definitions. 5.2.5 availability, steady state the steady state availability of the system is the 5.1 achieved limit of the availability function as time tends obtained as the result of measurement. to infinity. Source: MIL-STD-721C Source: Elsayed, E., Reliability Engineering, Addison Wesley, Reading, MA, 1996. 5.2.6 availability, inherent 5.2 availability inherent availability is the steady state ability of an item to be in a state to perform a availability when considering only the required function under given conditions at a corrective maintenance (CM) downtime of the given instant of time or over a given time system. interval, assuming that the required external Source: Elsayed, E., Reliability Engineering, Addison resources are provided. Wesley, Reading, MA, 1996. Source: ISO 14224:2006 5.2.7 availability, achieved 5.2.1 availability, instantaneous achieved availability is very similar to inherent pointwise or instantaneous availability, A(t), is availability with the exception that preventive the probability that an item is in a state to maintenance (PM) downtimes are also perform a required function under given included. conditions at a given instant of time, assuming Source: Elsayed, E., Reliability Engineering, Addison Wesley, Reading, MA, 1996. that the required external resources are provided. Source: Elsayed, E., Reliability Engineering, Addison 5.2.8 availability, operational Wesley, Reading, MA, 1996. operational availability is a measure of the "real" average availability over a period of time 5.2.2 availability, point and includes all experienced sources of see availability, instantaneous downtime, such as administrative downtime, logistic downtime, etc. Source: Elsayed, E., Reliability Engineering, Addison 5.2.3 availability, mean Wesley, Reading, MA, 1996. the mean availability is the proportion of time during a mission or time period that the system 5.3 age is available for use. Source: Elsayed, E., Reliability Engineering, Addison a measure of exposure to stress computed Wesley, Reading, MA, 1996. from the moment an item or component

enters service when new or re-enters service 5.2.4 availability, average up time after a task designed to restore its initial see availability, mean capability, and can be measured in terms of calendar time, running time, distance travelled, duty cycles or units of output or throughput. Source: SAE JA 1012

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5.4 demonstrated 5.9 maintenance man hours that which has been measured by the use of accumulated duration of the individual objective evidence gathered under specified maintenance times used by all maintenance conditions. personnel for a given type of maintenance Source: MIL-STD-721C action or over a given time interval. Source: ISO 14224:2006

5.5 direct man hours per maintenance action 5.10 maintenance time a measure of the maintainability parameter an element of down time which excludes related to item demand for maintenance modification and delay time. manpower: The sum of direct maintenance Source: MIL-STD-721C man hours, divided by the total number of maintenance actions during a stated period of 5.11 mean maintenance time time. Source: MIL-STD-721C the measure of item maintainability taking into account maintenance policy. The sum of 5.6 direct man hours per preventative and corrective maintenance times, divided by the sum of scheduled and maintenance event unscheduled maintenance events, during a a measure of the maintainability parameter stated period of time Source: MIL-STD-721C related to item demand for maintenance manpower: The sum of direct maintenance man hours, divided by the total number of 5.12 surveillance period maintenance events during a stated period of time. interval of time (calendar time) between the Source: MIL-STD-721C start date and end date of RM data collection. Source: ISO 14224:2006

5.7 life 5.13 Time a measure of anticipated life of an asset of component, such as time, number of cycles, the universal measurement of duration. distance intervals, etc. Source: MIL-STD-721C Source: IIMM V3.0 5.13.1 time, active 5.8 logistic delay that time during which an item is in operational inventory. that accumulated time during which Source: MIL-STD-721C maintenance cannot be carried out due to the necessity to acquire maintenance resources, 5.13.2 time, active maintenance excluding any administrative delay. Source: ISO 14224:2006 that part of the maintenance time during which a maintenance action is performed on

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an item, either automatically or manually, 5.13.10 time, mission excluding logistic delays. that element of up time required to perform a Source: ISO 14224:2006 stated mission profile. Source: MIL-STD-721C 5.13.3 time, administrative 5.13.11 time, not operating that element of delay time, not included in the supply delay time. that element of uptime during which the item Source: MIL-STD-721C is not required to operate. Source: MIL-STD-721C

5.13.4 time, alert 5.13.12 time, operating that element of up time during which an item is assumed to be in specified operating time interval during which an item is in condition and is awaiting a command to operating state. Source: ISO 14224:2006 perform its intended mission.

Source: MIL-STD-721C 5.13.13 time, reaction 5.13.5 time, checkout that element of uptime needed to initiate a that element of maintenance time during mission, measured from the time command is which performance of an item is B10verified to received. Source: MIL-STD-721C be of a specified condition.

Source: MIL-STD-721C 5.13.14 time, supply delay 5.13.6 time, delay that element of delay time during which a that element of down time during which no needed replacement item is being obtained. Source: MIL-STD-721C maintenance is being accomplished because of either supply or administrative delay. Source: MIL-STD-721C 5.13.15 time, turn around

that element of maintenance time needed to 5.13.7 time, down replenish consumables and check out an item time interval during which an item is in a down for recommitment. Source: MIL-STD-721C state.

Source: ISO 14224:2006 5.14 uptime 5.13.8 time, idle time interval during which an item is in an up part of the up time that an item is not state. operating. Source: ISO 14224:2006 Source: ISO 14224:2006

5.13.9 time, inactive that time during which an item is in reserve. Source: MIL-STD-721C

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5.15 useful life Source: MIL-STD-721C the number of life units from manufacture to 5.17 wearout when the item has an unrepairable failure or unacceptable failure rate. the process which results in an increase of the Source: MIL-STD-721C failure rate or probability of failure with

increasing number of life units. 5.16 utilization rate Source: MIL-STD-721C the planned or actual number of life units expended, or missions attempted during a stated interval of calendar time.

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6 General Definitions – Sources This table lists definitions for each terms from all sources listed in Table 1. The preferred choice as determined by the focus group is indicated with bold text. Relevant terms from ISO 55000 FDIS 2013 have been added to this table.

General Definitions

Term Definition Source

action, corrective Action to eliminate the cause of a detected nonconformity or PAS 55-1:2008 other undesirable situation. A documented design, process, procedure, or materials MIL-STD-721C change implemented and validated to correct the cause of failure or design deficiency asset Something that has potential or actual value to an ISO 55000 organization FDIS Plant, machinery, property, buildings, vehicles and other items PAS 55-1:2008 that have a distinct value to the organisation. asset, critical asset having the potential to significantly impact on the ISO 55000 achievement of the organization’s objectives FDIS

asset hierarchy A framework for segmenting an asset base into appropriate IIMM V3.0 classifications. The asset hierarchy can be based on asset function; asset type or a combination of the two. A hierarchical representation of the asset base with New associated classifications.

asset Systematic and coordinated activities and practices through PAS 55-1:2008 management which an organisation optimally and sustainably manages its assets and asset systems, their associated performance, risks and expenditures over their lifecycles for the purpose of achieving its organisational strategic plan. Coordinated activity of an organization to realize value from ISO 55000 assets FDIS

The combination of management, financial, economic, IIMM V3.0 engineering and other practices applied to physical assets with the objective of providing the required level of service in the most cost effective manner. asset Result to be achieved ISO 55000 management FDIS objective

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asset Document specifying activities and resources, responsibilities PAS 55-1:2008 management and timescales for implementing the asset management plan strategy and delivering the asset management objectives. Formulation of a programme to achieve an objective. An ISO 55000 asset management plan can be for an asset, asset type, asset FDIS system or asset portfolio, service or product A plan developed for the management of one or more IIMM V3.0 infrastructure assets that combines multi-disciplinary management techniques over the lifecycle of the asset in the most cost-effective manner to provide a specified level of service. A significant component of the plan is a long term cashflow projection for the activities. asset intentions and direction of an organization as formally ISO 55000 management expressed by its top management FDIS policy Principles and mandated requirements derived from, and PAS 55-1:2008 consistent with the organisational strategic plan, providing a framework for the development and implementation of the asset management strategy and the setting of the asset management objectives. asset Long term optimised approach to management of the assets, PAS 55-1:2008 management derived from, and consistent with, the organisational strategy strategic plan and the asset management policy. asset Management system for asset management that is there to ISO 55000 management establish the asset management policy and asset FDIS system management objectives.

components Specific parts of an asset having independent physical or IIMM V3.0 functional identity and having specific attributes such as different life expectancy, maintenance regimes, risk or criticality. Specific parts of an asset having independent physical or New functional identity. condition Detection and collection of information and data that indicate ISO monitoring the state of a machine. 13372:2004(E) Continuous or periodic inspection, assessment, measurement IIMM V3.0 and interpretation of the resultant data, to indicate the condition of a specific component so as to determine the need for some preventative or remedial action. Continuous or periodic inspection, assessment, New measurement and interpretation of the resultant data, to indicate the need for maintenance Action Corrective action action to eliminate the cause of a nonconformity and to ISO 55000 prevent recurrence FDIS

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a documented design, process, procedure, or materials MIL-STD-721C change implemented and validated to correct the cause of failure or design deficiency demand Activation of the function (includes functional, operational ISO and test activation). 14224:2006 dependability A measure of the degree to which an item is operable and MIL-STD-721C capable of performing its’ required function at any (random) time during a specified mission profile, given item availability at the start of the mission. The collective term used to describe the availability AS IEC 60300.2 performance and its influencing factors: reliability performance, maintainability performance, and maintenance support performance. desired The level of performance desired by the owner or user of a SAE JA 1012 performance physical asset or system. discard Removal from service of an item at a specified life limit. AS IEC 60300.3.11 disposal Activities necessary to dispose of decommissioned assets. PAS 55-1:2008 environment The aggregate of all external and internal conditions (such MIL-STD-721C as temperature, humidity, radiation, magnetic and electrical fields, shock vibration) either natural or man made, or self induced, that influences the form, performance, reliability or survival of an item. equipment class Class of similar type of equipment units (e.g. all pumps). ISO 14224:2006 equipment data Technical, operational and environmental parameters ISO characterizing the design and use of an equipment unit. 14224:2006 equipment unit Specific equipment unit within an equipment class as ISO defined by its boundary (e.g. one pump). 14224:2006 error Discrepancy between a computed, observed or measured ISO value or condition and the true, specified or theoretically 14224:2006 correct value or condition. failure data Data characterizing the occurrence of a failure event. ISO 14224:2006 Data characterizing the occurrence of a failure event and New conditions leading up to the event.

function Normal characteristic actions of an item AS IEC 60300.3.11 What the owner or user of a physical asset or system wants SAE JA 1011 / it to do. SAE JA 1012 function, primary The function(s) which constitute the main reason(s) why a SAE JA 1011 / physical asset or system is acquired by its owner or user. SAE JA 1012

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function, Functions which a physical asset or system has to fulfil apart SAE JA 1012 secondary from its primary function(s), such as those needed to fulfil regulatory requirements and those which concern issues such as protection, control, containment, comfort, appearance, energy efficiency and structural integrity. functional failure Failure, the effect of which is that an entity fails to perform AS IEC one or more of its required functions. 60300.3.11 A state in which a physical asset or system is unable to SAE JA 1011 / perform a specific function to a desired level of performance. SAE JA 1012 inspection Examination of an item against a specific standard. AS IEC 60300.3.11 item Any part, component, device, subsystem, functional unit, ISO equipment or system that can be individually considered. 14224:2006 / AS IEC 60300.3.14- 2005 A non-specific term used to denote any product, including MIL-STD-721C systems, material parts, subassemblies, sets, accessories, etc. level of service The defined service quality for a particular activity or service IIMM V3.0 area against which service performance may be measured. Service levels usually relate to quality, quantity, reliability, responsiveness, environmental acceptability and cost. life profile A time-phased description of the events and environments MIL-STD-721C an item experiences from manufacture to final expenditures or removal from the operational inventory, to include one or more mission profiles. life units A measure of use duration applicable to the item (e.g., MIL-STD-721C operating hours, cycles, distance, rounds fired, attempts to operate etc.). Life cycle Time interval that commences with the identification of the PAS 55-1:2008 need for an asset and terminates with the decommissioning of the asset or any associated liabilities. The stages involved in the management of an asset ISO 55000 FDIS The cycle of activities that an asset (or facility) goes through IIMM V3.0 while it retains an identity as a particular asset, i.e. From planning and design to decommissioning or disposal. lifecycle cost The total cost of an asset throughout its life including IIMM V3.0 planning, design, construction, acquisition, operation, maintenance, rehabilitation and disposal costs. The cost of acquisition and ownership of a product over a AS IEC 60300.2 defined period of its lifecycle. It may include the cost of development, acquisition, operation, support and disposal of the product.

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The sum of acquisition cost and ownership cost of a product AS/NZS over its life cycle 4536:1999 acquisition cost The initial cost to gain possession of the completed product. AS/NZS Includes any research, development, testing, evaluation 4536:1999 costs, as well as the investment and installation cost. ownership cost summation of all operating expenses, maintenance, support AS/NZS and disposal costs borne by the owner or user of a complete 4536:1999 product during its life cycle maintainability General Ability of an item under given conditions of use, to ISO be retained in, or restored to, a state in which it can perform a 14224:2006 / 〈 〉 required function, when maintenance is performed under AS IEC given conditions and using stated procedures and resources. 60300.3.14- 2005 The measure of the ability of an item to be retained in or MIL-STD-721C restored to specified condition when maintenance is performed by personnel having specified skill levels, using prescribed procedures and resources, at each prescribed level of maintenance and repair. The ability of an item , under stated conditions of use, to be BS4778 retained in, or restored to, a state where it can perform its required functions, when maintenance is performed under stated conditions and using prescribed procedures and resources. maintainable Item that constitutes a part or an assembly of parts that is ISO item normally the lowest level in the equipment hierarchy during 14224:2006 maintenance. maintenance Combination of all technical and administrative actions, ISO including supervisory actions, intended to retain an item in, or 14224:2006 / restore it to, a state in which it can perform a required AS IEC function. 60300.3.14- 2005 All actions necessary for retaining an item in or restoring it MIL-STD-721C to a specified condition maintenance Sequence of elementary maintenance activities carried out for AS IEC action a given purpose. 60300.3.14— 2005 An element of a maintenance event. One of more tasks (i.e., MIL-STD-721C fault localization, fault isolation, servicing and inspection) necessary to retain an item in or restore it to a specified condition. maintenance Data characterizing the maintenance action planned or done. ISO data 14224:2006 maintenance Impact of the maintenance on the plant or equipment’s ISO impact function(s). 14224:2006

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maintenance Collated information, policies and procedures for the IIMM V3.0 plan optimum maintenance of an asset, or group of assets. maintenance ` General approach to the provision of maintenance and AS IEC policy maintenance support based on the objectives and policies of 60300.3.14— owners, users and customers. 2005 maintenance Methods, procedures and resources required for sustaining AS IEC programme the support of an item throughout its lifecycle. 60300.3.11 maintenance Part of maintenance documentation that contains all failures, ISO record faults and maintenance information relating to an item. 14224:2006 All documentation related to a maintenance activity New maintenance Resources required to maintain an item under a given AS IEC support maintenance concept and guided by a maintenance policy. 60300.3.14— 2005 Resources required to maintain an item New maintenance Ability of a maintenance organisation, under given AS IEC support conditions, to provide upon demand, the resources required 60300.3.14— performance to maintain an item, under a given maintenance concept and 2005 guided by a maintenance policy. maintenance task Action or set of actions required to achieve a desired AS IEC outcome which restores an item to (or maintains an item in) 60300.3.11 serviceable condition, including inspection and determination of condition. maintenance, Maintenance performed after a machine has failed ISO breakdown 13372:2004(E) maintenance, Maintenance performed as governed by condition monitoring ISO condition based programmes. 13372:2004(E) Maintenance actions triggered by the condition or New performance of a function maintenance, Maintenance carried out after fault recognition and intended ISO corrective to put an item into a state in which it can perform a required 14224:2006 function. The remedial actions performed as a result of failure, to IIMM V3.0 restore an item to a specified condition. Corrective maintenance may or may not be programmed. The actions performed, as a result of failure, to restore an MIL-STD 2173 item to a specified condition All actions performed as a result of failure, to restore an item MIL-STD-721C to a specified condition. Corrective maintenance can include any or all of the following steps: Localization, Isolation, Disassembly, Interchange, Reassembly, Alignment and Checkout. The maintenance carried out after failure has occurred and BS4778 intended to restore an item to a state in which it can perform its required function

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The actions performed, as a result of failure, to restore an MIL-STD 2173 item to a specified condition maintenance, Maintenance of an item that is deferred or advanced in time ISO opportunity when an unplanned opportunity becomes available. 14224:2006 maintenance, Maintenance emphasising prediction of failure and taking ISO predictive action based on the condition of the equipment to prevent 13372:2004(E) failure or degradation maintenance, Maintenance carried out at predetermined intervals or ISO preventive according to prescribed criteria and intended to reduce the 14224:2006 probability of failure or the degradation of the functioning of an item. Maintenance performed according to a fixed schedule, or ISO according to a prescribed criterion that detects or prevents 13372:2004(E) degradation of a functional structure, system, or component, in order to sustain or extend its useful life. Maintenance carried out at predetermined intervals or AS IEC according to prescribed criteria and intended to reduce the 60300.3.14— probability of failure or the degradation of the functioning of 2005 an item. Predictive planned maintenance - condition monitoring IIMM V3.0 activities used to predict failure. All actions performed in an attempt to retain an item in MIL-STD-721C specified condition by providing systematic inspection, detection, and prevention of incipient failures . Preventative planned maintenance - maintenance that can be IIMM V3.0 initiated without routine or continuous checking and is not condition based. The maintenance carried out at predetermined intervals or BS4778 corresponding to prescribed criteria and intended to reduce the probability of failure or the performance degradation of an item. maintenance, Type of maintenance emphasising the routine detection and ISO proactive correction of root cause conditions that would otherwise lead 13372:2004(E) to failure. Maintenance undertaken before a failure occurs, in order to SAE JA 1012 prevent the item from getting into a failed state (scheduled restoration, scheduled discard, and on-condition maintenance). Term that encompasses condition based maintenance, fixed New interval maintenance and run to failure maintenance, Preventive maintenance carried out in accordance with an AS IEC scheduled established time schedule. 60300.3.14— 2005

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Preventative maintenance performed at prescribed points in MIL-STD-721C the items life. All maintenance carried out in accordance with an New established schedule maintenance, Corrective work required in the short term to restore an asset IIMM V3.0 unplanned to working condition so it can continue to deliver the required service or maintain its level of security and integrity. All maintenance not carried out in accordance with an New established schedule (need to add clarifying note that this is NOT breakdown maintenance) maintenance, Maintenance carried out, not in accordance with an AS IEC unscheduled established time schedule, but after reception of an indication 60300.3.14— regarding the state of an item. 2005

An element of down time which excludes modification and MIL-STD-721C delay time. See maintenance, unplanned New modification Combination of all technical and administrative actions ISO intended to change an item. 14224:2006 not operating The state wherein an item is able to function but is not MIL-STD-721C required to function. operable The state of being able to perform the intended function MIL-STD-721C operating context The circumstances in which a physical asset or system is SAE JA 1012 expected to operate. operating state State when an item is performing a required function. ISO 14224:2006 operation The active process of utilising an asset which will consume IIMM V3.0 resources such as manpower, energy, chemicals and materials. Operation costs are part of the lifecycle costs of an asset. organisation Overall long term plan for the organisation that is derived PAS 55-1:2008 strategic plan from, and embodies, its vision, mission, values, business policies, stakeholder requirements, objectives and the management of its risks. owner A person or organisation that may either suffer or be held SAE JA 1012 accountable for the consequences of a failure mode by virtue of ownership of the asset or system. predicted That which is expected at some future time, postulated on MIL-STD-721C analysis of past experience and tests. predictive action Action to monitor the condition of an asset and predict the ISO 55000 need for preventative action or corrective action FDIS preventative action to eliminate the cause of a potential non-conformity ISO 55000 action or other undesirable potential situation FDIS procedure Specified way of carrying out an activity or a process. PAS 55-1:2008

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process Set of interrelated or interacting activities which transforms ISO 55000 inputs into outputs. FDIS reassembly Assembling the items that were removed during disassembly MIL-STD-721C and closing the reassembled items. record Document stating results achieved or providing evidence of PAS 55-1:2008 activities performed. redundancy Existence of more than one means for performing a required ISO function of an item. 14224:2006 The existence of more than one means for accomplishing a MIL-STD-721C given function. Each means of accomplishing the function need not necessarily be identical. Existence of means, in addition to the means which would be IEC 61508 Part sufficient for a functional unit to perform a required function 4 or for data to represent information. redundancy, That redundancy wherein all redundant items are operating MIL-STD-721C active simultaneously. That redundancy wherein redundant items are operating New simultaneously. redundancy, That redundancy wherein the alternative means of MIL-STD-721C standby performing the function is not operating until it is activated upon failure of the primary means of performing the function. reliability Ability of an item to perform a required function under given ISO conditions for a given time interval. 14224:2006 The probability that an item can perform its intended MIL-STD-721C function for a specified interval under stated conditions. The duration or probability of failure-free performance under MIL-STD-721C stated conditions. Probability that a machine will perform its required functions ISO without failure for a specified time period when used under 13372:2004(E) specified conditions. reliability centred Systematic approach for identifying effective and efficient new maintenance maintenance tasks for items in accordance with a specific set of procedures and for establishing intervals between maintenance tasks. reliability growth The improvement in a reliability parameter caused by the MIL-STD-721C successful correction of deficiencies in item design or manufacture. reliability, Reliability data covering families of similar equipment. ISO generic data 14224:2006

repair See maintenance, corrective. repairable item An item which can be restored to perform all of its required MIL-STD-721C functions by corrective maintenance.

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required function Function or combination of functions of an item that is ISO considered necessary to provide a given service. 14224:2006 AS IEC ISO 13372:2004(E)0AS IEC 60812-200800.AS IEC ISO 60300.2 Appropriate action of any machine or part of a 13372:2004(E) system. requirement Need or expectation that is stated, generally implied or ISO 55000 obligatory FDIS run to failure A failure management policy that permits a specific failure SAE JA 1012 mode to occur without any attempt to anticipate or prevent it. Maintenance approach that permits a specific failure mode new to occur scheduled A scheduled task that entails discarding an item at or before SAE JA 1011 / discard a specified age limit regardless of its condition at the time. SAE JA 1012 scheduled A scheduled task that restores the capability of an item at or SAE JA 1011 / restoration before a specified interval (age limit), regardless of its SAE JA 1012 condition at the time, to a level that provides a tolerable probability of survival to the end of another specified interval. servicing The performance of any act needed to keep an item in MIL-STD-721C operating condition, (i.e. Lubricating, fuelling, oiling, cleaning, etc.) but not including preventative maintenance of parts of corrective maintenance tasks. The performance of any act needed to keep an item in new operating condition, (i.e. Lubricating, fuelling, oiling, cleaning, etc.) subunit Assembly of items that provides a specific function that is ISO required for the equipment unit within the main boundary to 14224:2006 achieve its intended performance. Item or assembly of items within a system hierarchy that new provides a specific function required for the system unit to achieve its intended performance subsystem A combination of sets or groups which performs an MIL-STD-721C operational function within a system. system Grouping of associated entities, which is characterised by a ISO mental construct. 13372:2004(E) Set of assets that interact or are interrelated ISO 55000 FDIS Set of interrelated or interacting elements. AS IEC 60300.3.14— 2005 Set of elements that interact according to a design, there an IEC 61508 Part element of a system can be another system, called subsystem, 4

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which may be a controlling system or a controlled system and may include hardware, software and human interaction. tag number Number that identifies the physical location of equipment. ISO 14224:2006 Number that can identify the physical location of equipment new or an individual asset taxonomy Systematic classification of items into generic groups based ISO on factors possibly common to several of the items. 14224:2006 test Experiment carried out in order to measure, quantify or AS IEC classify a characteristic or a property of an item. 60300.3.11 user A person or organisation that operates an asset or system and SAE JA 1011 / may either suffer or be held accountable for the SAE JA 1012 consequences of a failure mode of that system. wearout The process which results in an increase of the failure rate or MIL-STD-721C probability of failure with increasing number of life units.

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7 Failure Definitions – Sources This table lists all given choices for the term. The agreed choice for the term is indicated with bold text.

Failure Definitions Term Definition Definition criticality Numerical index of the severity of an effect combined with AS IEC the probability or expected frequency of its occurrence. 60300.3.11 A relative measure of the consequence of a failure mode MIL-STD-721C and its frequency of occurrences. criticality analysis A procedure by which each potential failure mode is MIL-STD-1629A ranked accordingly to the combined influence of severity and probability of occurrence damage, Physical deterioration of an item caused by contact or AS IEC accidental impact with an object or equipment, or maintenance. 60300.3.11 damage, The result(s) or consequence(s) indirectly caused by the MIL-STD-1629A secondary effects interaction of a damage mode with a system, subsystem or component thereof. degradation A gradual impairment of ability to perform. MIL-STD-721C failure Termination of the ability of an item to perform a ISO required function. 14224:2006 /ISO 13372 / AS IEC 60300.2 / AS IEC 60300.3.11 / AS IEC 60812 The event or inoperable state in which an item or part of MIL-STD-721C an item does not, or would not , perform as previously specified. An unacceptable deviation from the design tolerance; NASA 2002 inability to meet a standard; non performance of what is requested or expected. failure analysis Subsequent to a failure, the logical systematic examination MIL-STD-721C of an item, its construction, application, and documentation to identify the failure mode and determine the failure mechanism and its basic course. The logical systematic examination of an item, its new construction, application, and documentation to identify the failure mode and determine the failure mechanism and its basic course. failure cause Circumstances associated with design, manufacture, ISO installation, use and maintenance that have led to a failure. 14224:2006

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The circumstances during design, manufacture or use AS IEC which have led to a failure. 60300.3.11 The physical or chemical processes, design defects, quality MIL-STD-1629A defects, part misapplication, or other processes which are the basic reason for failure or which initiate the physical process which by deterioration proceeds to failure failure The way(s) in which the effects of a failure mode or a SAE JA 1012 consequences multiple failure matter (evidence of failure, impact on safety, the environment, operational capability, direct and indirect repair costs). A classification of the failure effects of failure modes into SAE JA categories based on evidence of failure, impact on safety, 1011SAE JA the environment, operational capability and cost. 1011 failure data Data characterizing the occurrence of a failure event. ISO 14224:2006 failure effect Consequence of a failure mode in terms of the operation, AS IEC 60812- function or status of the item. 2008 The consequence(s) a failure mode has on the operation, MIL-STD-721C function, or status of an item. Failure efforts are classified as local effect, next higher level, and end effect. What happens when a failure mode occurs. SAE JA 1011 / SAE JA 1012 What is observed when a failure mode occurs new failure impact Impact of a failure on an equipment's function(s) or on ISO the plant. 14224:2006 failure The physical, chemical, electrical, thermal or other ISO mechanism process which results in failure. 14224:2006 failure mode Effect by which a failure is observed on the failed item. ISO 14224:2006 Effect by which a failure is observed. ISO 13372:2004(E) One of the possible states of a failed item, for a given AS IEC required function. 60300.3.11 Manner in which an item fails. AS IEC 60812- 2008 The consequence of the mechanism through which the MIL-STD-721C failure occurs. I.e. short, open, fracture, excessive wear. A single event, which causes a functional failure. SAE JA 1011 / SAE JA 1012 failure mode and A procedure by which each potential failure mode in a MIL-STD-721C effects analysis system is analysed to determine the results or effects thereof on the system and to classify each potential failure mode according to its severity.

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failure on Failure occurring immediately when the item is solicited to ISO demand start (e.g. stand-by emergency equipment). 14224:2006 Failure occurring unexpectedly when the item is required new (e.g. stand-by emergency equipment). failure, Sudden unexpected failure of a machine resulting in ISO catastrophic considerable damage to the machine and/or associated 13372:2004(E) machines or components. A failure that can cause item loss. MIL-STD-721C failure, common Failures of different items resulting from the same direct ISO cause cause, occurring within a relatively short time, where 14224:2006 these failures are not consequences of another. failure, critical Failure of an equipment unit that causes an immediate ISO cessation of the ability to perform a required function. 14224:2006 A failure, or combination of failures, that prevents an item MIL-STD-721C from performing a specified mission. failure, degraded Failure that does not cease the fundamental function(s), ISO but compromises one or several functions. 14224:2006 failure, Failure which is caused by the failure of an associated MIL-STD-721C dependant item(s). failure, evident A failure mode whose effects become apparent to the SAE JA 1011 / operating crew under normal circumstances if the failure SAE JA 1012 mode occurs on its own. failure, evident The deterioration profile of an evident failure New progression failure, hidden Failure that is not immediately evident to operations and ISO maintenance personnel. 14224:2006 A failure mode whose effects do not become apparent to SAE JA 1011 / the operating crew under normal circumstances if the SAE JA 1012 failure mode occurs on its own. A failure mode whose effects are not readily apparent new failure, hidden The assumed deterioration profile of a hidden failure new progression failure, incipient Imperfection in the state or condition of an item so that a ISO degraded or critical failure might (or might not) eventually 14224:2006 be the expected result if corrective actions are not taken failure, Failure which occurs without being caused by the failure MIL-STD-721C independent of any other item. failure, Failure for a limited period of time, followed by the item's MIL-STD-721C intermittent recovery of its ability to-perform within specified limits without any remedial action. Failure of an item for a limited period of time, following BS4778 which the item restores its required function without being subjected to any external corrective action.

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failure, non- Failure of an equipment unit that does not cause an ISO critical immediate cessation of the ability to perform its required 14224:2006 function. failure, potential An identifiable condition that indicates that a functional SAE JA 1011 / failure is either about to occur or is in the process of SAE JA 1012 occurring. failure, single The failure of an item which would result in failure of the MIL-STD-721C point system and is not compensated for by redundancy or alternative operational procedure. failure, A postulated failure mode in the FMEA for which there is MIL-STD-1629A undetectable no failure detection method by which the operator is made aware of the failure. fault State of an item characterized by inability to perform a ISO required function, excluding the inability during 14224:2006 / preventative maintenance or other planned actions, or AS IEC 60300.2 due to lack of external resources. / AS IEC 60812- 2008 Condition of a component that occurs when one of its ISO components or assemblies degrades or exhibits abnormal 13372:2004(E) behaviour, which may lead to failure of the machine. Abnormal condition that may cause a reduction in, or loss IEC 61508 Part of the capability of a functional unit to perform the 4 required function. The immediate cause of failure (e.g. Maladjustment, MIL-STD-721C misalignment, defect etc). A defect, imperfection, mistake or flaw of varying severity NASA 2002 that occurs within some hardware or software component of a system. "Fault" is a general term and can range from a minor defect to a failure fault isolation The process of determining the location of a fault to the MIL-STD-721C extent necessary to effect repair. fault localization The process of determining the approximate location of MIL-STD-721C the fault. infant mortality The relatively high conditional probability of failure MIL-STD 2173 during the period immediately after an item enters service. Such failures are due to defects in manufacturing not detected by quality control interchange Removing the item to be replaced, and installing the MIL-STD-721C replacement item. local effect The consequence a failure mode has on the operation, MIL-STD-1629A function or status of the specific item being analysed. nonconformity Non-fulfilment of a requirement ISO 55000 FDIS risk Effect of uncertainty on objectives ISO 31000

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severity The consequences of a failure mode. Severity considers MIL-STD-1629A the worst potential consequence of a failure, determined by the degree of injury, property damage, or system damage that could ultimately occur

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8 Time Definitions – Sources This table lists all given choices for the term. The agreed choice for the term is indicated with bold text.

Time Definitions Term Definition Definition achieved Obtained as the result of measurement. MIL-STD-721C age A measure of exposure to stress computed from the SAE JA 1011 / SAE JA moment an item or component enters service when 1012 new or re-enters service after a task designed to restore its initial capability, and can be measured in terms of calendar time, running time, distance travelled, duty cycles or units of output or throughput. availability Ability of an item to be in a state to perform a ISO 14224:2006 required function under given conditions at a given instant of time or over a given time interval, assuming that the required external resources are provided. Probability that a machine will, when used under ISO 13372:2004(E) specified conditions, operate satisfactorily and effectively. A measure of the degree to which an item is in an MIL-STD-721C operable and committable state at the start of a mission when the mission is called for at an unknown (random time). (Item state at start of a mission includes the combined effects of the readiness- related system R & M parameters, but excludes mission time. The ability of the item (under combined aspects of its BS4778 reliability, maintainability, and maintenance support) to perform its required function at a stated instant of time or over a stated period of time availability, Pointwise or instantaneous availability, A(t), is the Reliability instantaneous probability that an item is in a state to perform a Engineering, Addison availability, point required function under given conditions at a given Wesley, Reading, instant of time, assuming that the required external MA, 1996. resources are provided. availability, mean The mean availability is the proportion of time Reliability availability, during a mission or time period that the system is Engineering, Addison average up time available for use. Wesley, Reading, MA, 1996. availability, The steady state availability of the system is the limit Reliability steady state of the availability function as time tends to infinity. Engineering, Addison

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Wesley, Reading, MA, 1996. availability, Inherent availability is the steady state availability Reliability inherent when considering only the corrective maintenance Engineering, Addison (CM) downtime of the system. Wesley, Reading, MA, 1996. availability, Achieved availability is very similar to inherent Reliability achieved availability with the exception that preventive Engineering, Addison maintenance (PM) downtimes are also included. Wesley, Reading, MA, 1996. availability, AS IEC ISO 13372:2004(E)0AS IEC 60812-200800.AS Reliability operational IEC 60300.2AS IEC 60300.3.11AOperational Engineering, Addison availability is a measure of the "real" average Wesley, Reading, availability over a period of time and includes all MA, 1996. experienced sources of downtime, such as administrative downtime, logistic downtime, etc. demonstrated That which has been measured by the use of MIL-STD-721C objective evidence gathered under specified conditions. direct man hours A measure of the maintainability parameter related MIL-STD-721C per maintenance to item demand for maintenance manpower: The action sum of direct maintenance man hours, divided by the total number of maintenance actions during a stated period of time. direct man hours A measure of the maintainability parameter related MIL-STD-721C per maintenance to item demand for maintenance manpower: The event sum of direct maintenance man hours, divided by the total number of maintenance events during a stated period of time. failure rate The total number of failures, within an item MIL-STD-721C population, divided by the total number of life units expended by that population ,during a particular measurement interval under stated conditions. The failure rate is an average frequency, λ, of failure ISO 14224:2006 (i.e. a number of failures per unit of time). The rate at which failures occur as a function of new usage. (asset) life A measure of anticipated life of an asset of IIMM V3.0 component, such as time, number of cycles, distance intervals, etc. Period from asset creation to asset end of life ISO 55000 FDIS logistic delay That accumulated time during which maintenance ISO 14224:2006 cannot be carried out due to the necessity to acquire

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maintenance resources, excluding any administrative delay. maintenance Accumulated duration of the individual maintenance ISO 14224:2006 man hours times used by all maintenance personnel for a given type of maintenance action or over a given time interval. maintenance An element of down time which excludes MIL-STD-721C time modification and delay time. mean The measure of item maintainability taking into MIL-STD-721C maintenance account maintenance policy. The sum of time preventative and corrective maintenance times, divided by the sum of scheduled and unscheduled maintenance events, during a stated period of time surveillance Interval of time (calendar time) between the start ISO 14224:2006 period date and end date of RM data collection. Time The universal measurement of duration. MIL-STD-721C Time, active That time during which an item is in operational MIL-STD-721C inventory. time, active That part of the maintenance time during which a ISO 14224:2006 maintenance maintenance action is performed on an item, either automatically or manually, excluding logistic delays. time, That element of delay time, not included in the MIL-STD-721C administrative supply delay time. time, alert That element of up time during which an item is MIL-STD-721C assumed to be in specified operating condition and is awaiting a command to perform its intended mission. time, checkout That element of maintenance time during which MIL-STD-721C performance of an item is verified to be of a specified condition. time, delay That element of down time during which no MIL-STD-721C maintenance is being accomplished because of either supply or administrative delay time, down Time interval during which an item is in a down ISO 14224:2006 state. The period of time during which an item is not in a BS4778 condition to perform its required function time, down That element of active time during which an item is MIL-STD-721C not in condition to perform its required function. (reduces availability and dependability). time, idle Part of the up time that an item is not operating. ISO 14224:2006 time, inactive That time during which an item is in reserve. MIL-STD-721C

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time, mission That element of up time required to perform a MIL-STD-721C stated mission profile. time, not That element of uptime during which the item is not MIL-STD-721C operating required to operate. time, operating Time interval during which an item is in operating ISO 14224:2006 state. time, reaction That element of uptime needed to initiate a mission, MIL-STD-721C measured from the time command is received. time, supply That element of delay time during which a needed MIL-STD-721C delay replacement item is being obtained. time, turn That element of maintenance time needed to MIL-STD-721C around replenish consumables and check out an item for recommitment. time, uptime Time interval during which an item is in an up state. ISO 14224:2006 That element of active time during which an item is in MIL-STD-721C condition to perform its required functions. up time Time interval during which an item is in an up state. ISO 14224:2006 useful life Period over which a depreciable asset is expected to IIMM V3.0 be used. The number of production or similar units that is IIMM V3.0 expected to be obtained from the asset. The number of life units from manufacture to when MIL-STD-721C the item has an unrepairable failure or unacceptable failure rate. utilization rate The planned or actual number of life units expended, MIL-STD-721C or missions attempted during a stated interval of calendar time.

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