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1
Reliability Centered Maintenance - RCM
An Overview of the ‘Process’
Presented By:
Jeff Banks
Research Engineer
The Applied Research Laboratory at
The Pennsylvania State University
2
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.
3
Condition Based Maintenance Plus
DoD Guidebook, May 2008
4
Air Force RCM
5
Air Force
RCM and CBM+ Guidance
Reference: Robert Riegert, HAF/A4ID, 1 February 2012, Version 1.0
6
Air Force
RCM and CBM+ Guidance
Reference: Robert Riegert, HAF/A4ID, 1 February 2012, Version 1.0
7
Air Force
RCM and CBM+ Guidance
Reference: Robert Riegert, HAF/A4ID, 1 February 2012, Version 1.0
8
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.
9
References for DoD RCM
• There are two fundamental documents that provide the
material for conducting RCM for DoD.
10
Definition of RCM Using SAE
JA1011 and JA1012 Standards
11
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.
12
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
13
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
14
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.
15
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?
16
Example of Standard FMEA
(RCM Required)
17
Example FMECA Format
(Not RCM Required)
• Criticality information provides additional
context for decision making.
18
Example FMECA+ Format
(Not RCM Required)
• Additional sensor information provides organized
details for determining the on-condition tasks
19
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
20
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
21
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
22
SAE JA1012A Decision Diagram
23
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
24
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.
25
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
26
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
27
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.
28
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.
29
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.
30
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
31
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.
32
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
33
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.