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Reliability Centered Maintenance - RCM

An Overview of the ‘Process’

Presented By:

Jeff Banks

Research Engineer

The Applied Research Laboratory at

The Pennsylvania State University

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Reliability Centered

Maintenance - RCM

• What is Reliability Centered Maintenance?

• It is not:

– Hardware or Software

– A Type of Maintenance

– A Product that is Purchased

• It is a systematic process and methodology for

determining the most effective and efficient

maintenance management plan for a specific

platform, system or component.

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Condition Based Maintenance Plus

DoD Guidebook, May 2008

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Air Force RCM

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Air Force

RCM and CBM+ Guidance

Reference: Robert Riegert, HAF/A4ID, 1 February 2012, Version 1.0

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Air Force

RCM and CBM+ Guidance

Reference: Robert Riegert, HAF/A4ID, 1 February 2012, Version 1.0

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Air Force

RCM and CBM+ Guidance

Reference: Robert Riegert, HAF/A4ID, 1 February 2012, Version 1.0

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AFI 21-104 (11 December 2007): Selective

Management of Selected Gas Turbine

Engines

• RCM is an integral part of engine life management for all

engines covered by this instruction.

– RCM is an analytical process to determine the appropriate failure

management strategies, including preventive maintenance

requirements and other actions that are warranted to ensure safe

operations while balancing readiness and costs.

• Engine Trending and Diagnostics (ET&D) is a program

integrating hardware, software, technical documents, training,

maintenance, and diagnostic/prognostic processes to

quantify and monitor/manage engine health.

• Effective use of ET&D can reduce engine flight safety risk,

improve reliability, and optimize life cycle costs.

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References for DoD RCM

• There are two fundamental documents that provide the

material for conducting RCM for DoD.

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Definition of RCM Using SAE

JA1011 and JA1012 Standards

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Reasons for Initiating RCM

Activities that could trigger the performance of an RCM analysis include but are not

limited to:

• The system design has stabilized and the system is entering testing (Milestone

B).

• A significant design change has occurred (an Engineering Change Proposal

(ECP) has been executed), and no RCM analysis was previously performed.

• Unexpected failure rates have been identified (this analysis may be limited to

only those systems that are exhibiting excessive or costly failures.

• The system’s operating context has changed (for example: the system is being

exposed to a new climate, the system encounters a new thread (IEDs), etc.).

• Guiding documentation directs the conduct of time-based analyses, or at given

stages of the system life-cycle.

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The Major Elements of the Basic

RCM Process

• RCM Establishment and Planning

• Analysis:

– Define the function and functional failures of a specific platform, system or component.

– Then conduct a Failure Modes and Effects Analysis

– Identify the failure consequences

– Determine maintenance tasks and intervals.

• Analysis Audit

• Implementation

• Sustaining the RCM Program:

– RCM is a ‘Living Program’

– Implement a RCM management, training, benchmarking, and review process to provide feedback and measurement of progress toward asset management goals

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RCM Program Establishment

and Planning • Identify Planning Team

• Determine Scope of Analysis– Identify System Boundaries

– Determine Level of Analysis

– Determine Extent of Analysis

• Identify Ground Rules and Assumptions – Standard operating procedures

– Data sources

– Analytical methods

– Cost-benefit analysis methods

– Approaches to specific types of problems

– Default values (e.g., labor rates, equipment usage

rates, common material costs)

– Acceptable probabilities of failure for certain failure

modes based on severity

• Determine Manpower Considerations

• Identify Training and Certification

• Consider use of Modeling and Simulation

• Determine Data Sources

• Identify Funding Requirements– Involves identifying the costs to establish and sustain

the RCM program.

– Training costs, team member travel costs, facility and

material costs in support of analysis

• Develop Sustainment Plan– Living Process

1.1Identify Planning Team

Identify persons to support initial RCM Program planning

1.3 Identify Ground Rules and Assumptions

Identify the analysis enablers and constraints

1.4 Determine Manpower Considerations

Consider the manpower commitment, skills and organization to support the RCM program

1.5 Identify Training and Certification Requirements

Identify the training and/or certification expectations of each role supporting the RCM

program

1.8 Identify Funding Requirements

What are the costs inherent in establishing and sustaining an RCM program

1.6 Consider use of Modeling and Simulation (M&S)

M&S can be applied throughout life-cycle to augment RCM program

1.9 Develop Sustainment Plan

Identify how RCM program will be sustained throughout the equipment life cycle

1.7 Determine Data Sources

Identify data requirements and source, crucial to conducting the RCM analysis

1.2 Determine Scope Of Analysis

Extent of the RCM analysis effort to be applied to meet program objectives

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Important Factor: Participation

• RCM Lead/Champion: Directs the planning efforts, analysis preparations, analysis

performance, and overall program execution

• RCM Facilitator: A highly skilled and experienced RCM professional, who supports the

RCM Lead in preparing for an analysis, and leads an analysis team through the actual

conduct of an analysis

• Support Personnel:

– Engineering: Crucial to data collection and analysis efforts, and a key member in

performing the RCM analysis of the platform/system

– Cost/Budget Analysts: Performs high-level cost benefit analyses of recommendation

resulting from an analysis, and assists in budgeting for program execution

– Logistician: Another key member in supporting data collection and analysis.

Supports RCM analysis by providing system/supply chain expertise, and operational

context

• Operators and Maintainers: The most crucial member of the RCM analysis team. They

have a full understanding of operational context, and fill in data gaps that are not available

under current Information technology (IT) capabilities with practical experience and

expertise.

• In operating and maintaining the analyzed system, Operators and Maintainers have a full

understanding of the current support philosophy, and provide key insight into the impact of

any recommended changes.

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Steps for the Analysis Process:

Information and Decision

1. Identify System Functions: What does the user need

the system to do in its current operating context?

2. Identify Functional Failures: In what way can the

system fail (or fail to fulfill its function)?

3. Identify the Failure Modes: What causes the failures?

4. Identify the Failure Effects: What happens when

failures occur and what are the symptoms of failure?

5. Identify Failure Consequences: How and why does the

failure matter.

• Frequency of occurrence

• Severity of the failure mode

6. Determine Maintenance Tasks and Intervals: Can the

failure be predicted or prevented?

7. Identify Other Logical Actions: What can be done if the

failure cannot be predicted or prevented?

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Example of Standard FMEA

(RCM Required)

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Example FMECA Format

(Not RCM Required)

• Criticality information provides additional

context for decision making.

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Example FMECA+ Format

(Not RCM Required)

• Additional sensor information provides organized

details for determining the on-condition tasks

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FMECA Example: Aircraft Fuel

System

Precursors or symptoms prior to full functional failure

Sensors and sensor placement requirements

Health management processing

techniques for diagnosing and

prognosing symptoms

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Introduction to the Failure

Consequences (Decision Process)

• The consequences of every failure mode shall be formally

categorized.

– Hidden verse Evident Failure Modes

– Safety and Environmental (1st priority) and Economic (2nd

priority) consequences.

– Operational (1st priority) and Non-Operational (2nd

priority) consequences.

– Assessment of failure consequences shall be carried out

as if no specific task is currently being done to anticipate,

prevent or detect the failure.

Reference: SAE JA1011 Standard

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Classical RCM Decision Diagram

Process (Example Simple Version)

• SAE J1011 standard

requires that the decision

process assess the safety

and environmental

consequences of failure.

• This decision diagram does

not so that it is not a valid

SAE approach.

Operating Equipment Asset Management by John Mitchell

CBM

Preventative

Replace Part

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SAE JA1012A Decision Diagram

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Scheduled - Failure Management

Policies: On-Condition Tasks

• On-Condition Tasks (Predictive or Condition Based Maintenance) can be

implemented for a specific failure mode for maintenance if:

– There exists a clearly defined potential failure as well as a failure development

period as described by the P-F curve.

– It must be possible to do the on-condition task at intervals less than the P-F interval.

– The shortest time between the discovery of the potential failure and the

occurrence of the functional failure must be long enough to take action to avoid,

eliminate or minimize the consequences of the failure mode.

• On-Condition Tasks:

items that are inspected

are left in service, ‘on-

condition’ that the

considered failure mode is

unlikely to occur before the

next check.

Reference: SAE JA1012 Standard

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P-F Interval

“The interval between the occurrence of a potential failure and its decay into a functional failure”

Reference: Reliability-centred Maintenace , by John Moubray

Point where

failure starts

to occur

Vibration

Analysis

Detection

Oil

Analysis

DetectionAudible

Noise

Detection

Temperature

Detection

Conditio

n

Time Functional

Failure

If the P-F interval is too short,

PT&I technology may not be effective.

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Scheduled - Failure Management Policies:

Scheduled Restoration and Discard Tasks

• Scheduled Restoration and Discard Tasks (Preventative Maintenance) can be

implemented for a specific failure mode for maintenance if:

– There should be a clearly defined age at which there is an increase in the

conditional probability of the failure mode occurring.

– A sufficiently large proportion of the occurrences of this failure mode shall occur

after this age to reduce the probability of premature failure.

• Relationship between Age and Failure: The failure

management process should take into account the

conditional probability of some failure modes that will

increase with age, decrease with age or not change with

age.

• In general, these patterns are associated with direct

wear, fatigue, corrosion, oxidation and evaporation.

Reference: SAE JA1012 Standard

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Conditional Probability of Failure

• Type A - Constant or gradually increasing failure probability, followed by a pronounced wear-out region. An age limit may be desirable. (Typical of reciprocating engines.)

• Type B - Infant mortality, followed by a constant or slowly increasing failure probability. (Typical of electronic equipment.)

• Type C - Low failure probability when the item is new or just overhauled, followed by a quick increase to a relatively constant level.

• Type D - Relatively constant probability of failure at all ages.

• Type E* - Bathtub curve; i.e., infant mortality followed by a constant or gradually increasing failure probability and then a pronounced wear-out region. An age limit may be desirable, provided a large number of units survive to the age where wear-out begins.

• Type F - Gradually increasing failure probability, but no identifiable wear-out age. Age limit usually not applicable. (Typical of turbine engines.)

A and E characteristic of simple systems

B, C, D and F characteristic of complex systems with a dominant failure mode

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Scheduled - Failure Management

Policies: Failure Finding Tasks

• Failure Finding Tasks are conducted for hidden

failure modes, where it may not be evident that an

item has failed. – The intent is to reduce the probability of the occurrence of a multiple

failure involving the protection device (i.e. fire extinguishing system)

and protected system (i.e. vehicle).

– It should be taken into consideration that the failure finding task and

associated interval may leave hidden function in a failed state (i.e.

repeated testing of the fire extinguishing system over a period of time

may deplete the level so that it no longer functions).

• Combination Tasks may be implemented when a single

task does not mitigate or manage the impact of safety and

environmental failure modes.

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Failure Management Policies: One

Time Changes and Run to Failure

• Redesign: are recommended to

reduce the consequences of a

failure or resolve problems that

are identified during the RCM

analysis.

• They are unique activities that

include:

– Design changes

– Training program changes

– Operating procedures changes

– Emergency procedures changes

– Technical manuals changes

– The collection of additional data

– No scheduled maintenance

• No Scheduled Maintenance: There

are cases in which failures may

occur that have no significant impact

on the function of the system (i.e.

run to failure).

• It is more economical to allow the

failure to occur than to mitigate it.

• Run to failure will only be employed

when an appropriate scheduled task,

or cost effective proactive task

cannot be identified, and the

occurrence of the failure does not

have a safety or environmental

impact.

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Analysis Audit

• The ‘Analysis Audit’ ensures that completed analyses are:

– Technically sound

– Follow the guidance and processes of the owning organization

– Provide recommendations with defensible benefits

– Support Perform Management Review and the implementation.

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Implementation

• The most important part of the RCM process is implementing the

results of the analysis.

– Need to have a capable RCM lead/champion who can

socialize the results of the RCM analysis with the PM.

– The RCM Lead should work with the PM to request, allocate,

and prioritize available funding to meet program needs based

on the RCM results.

Analysis Audit completed

4.1 Perform

Management Review Management

approves or denies recommendations

Recommendation Approved?

Record Disapproval in Audit Package

Yes

No

4.2 Publish Finalized Analysis

Key document collected and published for use/

reference

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Sustaining the RCM Program

• RCM is a ‘Living Process’ that requires

periodic review and reassessment to

validate the analysis results and

decisions.

• Two Realities about RCM and Maintenance:

– The maintenance system, policies, personnel and technology will evolve and change.

– The analysis will not be ‘perfect’ the first time through the process but it should be noted where the program provided benefits.

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Sustaining the RCM Program

• Original RCM groups should review their results to consider the

following questions:

– Has the operating context of the equipment changed?

– Have the performance expectations of the equipment changed?

– Have any failure modes occurred or effects changed?

– Should the failure consequences be reconsidered for any reason?

– Are the maintenance tasks selected in the decision process still valid and worth conducting? Should the frequency be changed?

– Is there a better proactive technique to one selected for the failure mode?

– Should a maintenance task be conducted by someone different than the person selected?

– Has the equipment been modified to change any functions or failure modes?

Reliability-centred Maintenance, By John Moubray

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RCM Summary

• Make sure that the people who know the systems, participate in the analysis:

– Process can be conducted faster and is more effective and everyone will learn more.

– Inexperienced personnel will also gain a tremendous amount of valuable information when they participate but only if the ‘knowledgeable’ people participate.

• Having a trained facilitator lead the process:

– Provides a guide for getting the greatest benefit from the analysis.

• The RCM process is only as effective as what each individual contributes.

– The more effort put in, the better the results, which will provide confidence in the implementation.

• The RCM process is a ‘living’ methodology that must be revisited periodically for the most effective implementation.