module 3 terminology & concept

7/28/2019 Module 3 Terminology & Concept

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Module 3

UNIT I

"Copyright 2002, Information Spectrum, Inc. All Rights Reserved."

INTRODUCTION TO RCM

RCM TERMINOLOGY AND

CONCEPTS


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IntroductionModule Preview:

Failures

Introduction

Severity

Probability of Failure

Reliability

Types of Maintenance

Review and Summary

Criticality

RCM TERMINOLOGY AND CONCEPTS


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Module Objective:

This module will introduce basic

concepts and terminology used in theRCM process.

Introduction



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Module Objective: Introduction

1. Define Failure Terminology:

Functional Failure

Potential FailureFailure Mode

2. Introduce the concepts ofSeverity,

Probability of Failure, and Criticalityand

how they are related.



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Module Objective: Introduction

3. Introduce the concept ofReliability.

4. Define the following maintenance terms:- Scheduled Maintenance - Unscheduled Maintenance

- Preventive Maintenance - Corrective Maintenance

- Proactive Maintenance - Reactive Maintenance

- Condition Monitoring - Condition Based Maintenance

- Conditional Maintenance



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FAILURES



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FailureDefinitions:

1. FAILURE:An identifiable deviation from aspecified condition that is unsatisfactory to an

asset owner or manager.

RCM recognizes two types of failures:

FUNCTIONAL FAILURE -Inability of item toperform a specific function within specifiedperformance limits

POTENTIAL FAILUREDefinableanddetectable condition that indicates a

functional failure will occur



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FailureDefinitions:

2. FAILURE MODE - A specific physical

condition that causes a particularfunctional failure



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SEVERITY



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SeverityDefinition:

SEVERITY - A category assigned to a

failure mode based on the impacts of itspotential effects

qualitative measures used to

categorize the potential effects of failures.



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CATEGORY I (CATASTROPHIC)

Death or Permanent disability

Destruction of system/equipment

Significant breach of environmental

regulation Damage > $1M

CATEGORY III (MARGINAL)

Damage >$10K and < $100K

Degraded ability to perform critical mission

Interrupted operations

CATEGORY II (CRITICAL)

Personal Injury

Inability to perform primary mission

Damage >$100K and < $1M

CATEGORY IV (MINOR)

Unscheduled maintenance or repair

Damage


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CATEGORY I (CATASTROPHIC)

Death or Severe Injury

Significant Environmental Impact

Loss of availability > 1 week

Damage > $1M

CATEGORY III (MARGINAL)

Loss of availability > 4 hrs and < 24 hrs

Damage >$10K and < $100K

CATEGORY II (CRITICAL)

Minor Injury

Loss of availability > 24 hrs and < 7 days


CATEGORY IV (MINOR)

Loss of availability < 4 hrs

Damage


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PROBABILITY OFFAILURE



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Probability of FailureDefinition:

1.Probability of failure: The probabil i ty that a given failuremode wil l occur dur ing a defined period.

2.Acceptable Probability of Failure (Pacc):Theprobabil ity of a given failure mode occurr ing during a defined per iod that

is acceptable to a program or asset manager.

The more severe the consequences, the lower Pacc

should be

Values may be defined by regulatory organizations

or self imposed (by a program or asset manager)

Values should be documented prior to analysis



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Probability of FailureDefinition:

3. Actual Probability of Failure (Pact): The predictedor demonstrated probabil i ty of a given failure mode occurr ing dur ing

a defined per iod in the operating environment.

Pactcan be measured from in-service data or estimated

from statistical failure distributions



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CRITICALITY



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CRITICALITY - A prioritization of the

combination of failure severity and failure

frequency (or probability)

Sometimes referred to as Risk

Criticality may bedocumented qualitatively

or quantitatively(Ref: MIL-STD-1629)

Asset managers/Programs may define

acceptable criticality limits by use of aHazard Risk Matrix. (Qualitative Method)

Criticality can be used to set priorities for

analysis or define acceptable risk

CriticalityDefinition:



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Hazard Risk Matrix:FREQUENCY

SEVERITY

FREQUENT(A)

> 1 per 1,000Hours

PROBABLE (B)

> 1 per 10,000Hours

OCCASIONAL (C)

> 1 per 100,000Hours

REMOTE (D)

> 1 per 1,000,000Hours

IMPROBABLE (E)

< 1 per 1,000,000Hours

CATASTROPHIC (I)

CRITICAL (II)

MARGINAL (III)

MINOR (IV)

Death or Permanent disability

Significant Environmental breach

Damage > $1M, Downtime>2 days

Destruction of system/equipment

Personal Injury


Loss of availability > 24 hrs and

< 7 days

Damage >$10K and < $100K Loss of availability > 4 hrs and

< 24 hrs

Damage


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RELIABILITY



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Reliability

RELIABILITY - Probability that an

asset will perform its intended

function for a specified period of timeunder specified operating conditions

Actual Reliability is a function of the assets design,

manufacturing process, usage profile, operating

environment, and maintenance program.

Definitions:




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MAINTENANCETERMS




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Types of MaintenanceDefinition:

PREVENTIVE MAINTENANCEactions

performed periodically (or continuously)

prior to functional failure (or multiple

failure/demand requirements for hiddenfailures) to achieve the desired level of

safety and reliability for an item

These actions are performed to prevent orreduce consequences of failures.

Due to differences in the way the termScheduledMaintenanceis used, this course will attempt to use thetermPreventive Maintenanceonly




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Types of MaintenanceDefinition

PROACTIVE MAINTENANCEany tasks

used to predict or prevent equipmentfailures.

Similar toPreventive Maintenanceexcept that itgenerally excludes failure finding type tasks. Again,

definitions may vary




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CORRECTIVE MAINTENANCErepairs

or other corrective action taken after afailure has occurred

For the purposes of this course, the termUnscheduled

Maintenanceis synonymous withCorrective MaintenanceandReactive Maintenance




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CONDITION MONITORINGThe use of

specialized equipment to measure the

condition of equipment.

Vibration Analysis, Oil Analysis, and Thermography

are examples ofCondition Monitoringtechniques

Predictive Maintenance (PdM) and Prognosis and Health

Management (PHM) are usually interchangeable with

Condition Monitoring.




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Condition Based MaintenanceAn

equipment maintenance strategy based

on measuring the condition of

equipment in order to assess whether

it will fail during some future period,

and then taking appropriate action toavoid the consequences of that failure.




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Conditional or Opportunity Maintenance

Maintenance actions conducted as result of a

specific condition, or as a result of specific

circumstances or events.

Examples of Conditional Inspections

Hard Landing

Unscheduled disassembly

Power Interruption Over/Under Voltage

Lightning strike

Over stress

Unscheduled or scheduled shut-down




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Proactive Maintenance

Preventi ve Maintenance (PM)

Unscheduled Maintenance

Corrective Maintenance (CM)

Reactive Maintenance

Condition Based Maintenance

Condition Monitori ng

Predictive Maintenance

Prognosis Health Management (PHM)Potential fail ures

Repair s or corrective actions

Run to failu re

Failure has occurred

Preserves required functionality

Reduces unplanned downtime

Requires investment

Fixes failures in unplanned manner

Downtime unpredictable

Addresses only whats broken

RCM determines proper balance of planned and unplanned maintenance,along with Other Actions, to establish a Failure Management Strategy

Scheduled Maintenance

Types of MaintenanceSummary:




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Review and Summary

Introduction

RCM Terms & Concepts

Learning Objectives

Failures Severity

Probability of Failure

Criticality

Reliability

Maintenance Terms

Module Objective

Introduce the primary terminologyand basic concepts used in RCM



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