2. Overview
• Background
– Condition Based Maintenance
– Changing views of Maintenance
• History and background of RCM
• The RCM Process
• The RCM team
• The Seven Questions
• Results of the Analysis
3. What is RCM?
• Definition
– A process used to determine what must be done to
ensure that any physical asset continues to do what its
users want it to do in its present operating context
– Mitigate the consequences of failure
• Yeah, but what is it?
– Highly structured analysis process to:
• Devise maintenance policy
• Design for ease of maintenance & effective operation
– Consensus from all stakeholders
– Identification of critical maintenance practices
– Reduction of counterproductive maintenance practice
Key Enabler of Condition Based Maintenance
4. CBM is the application and integration of appropriate
processes, technologies, and knowledge based
capabilities to improve the reliability and maintenance
effectiveness of DoD systems and components. At its
core, CBM is maintenance performed on evidence of
need provided by reliability centered maintenance
(RCM) analysis and other enabling processes
CBM+ strives to optimize key performance measures of
materiel readiness - materiel availability, materiel
reliability, mean downtime, and ownership costs
Condition Based Maintenance
5. What does that mean?
• Do maintenance based upon the condition of the
asset; not on rigid time based schedules
– Reservists change clean oil on schedule even though
the vehicle may have less than 100 miles since the last
oil change
• More maintenance is not better maintenance
• Excessive preventive maintenance creates failures
– Infant mortality
• Asset Health Monitoring is key to successful CBM
– Sensor selection must be examined carefully
• CBM is third generation maintenance and is an
important step toward prognostic maintenance
10. Origin of RCM
• Boeing 747 and United Airlines
– MSG-1 (Maintenance Steering Group)(1968)
– DC-8 required 4 million man hours per 20,000 flight
hours
• (200 man hours per flight hour)
– Using RCM techniques 747 required 66,000 while
improving reliability
• (3.3 man hours per flight hour)
• MSG-2 & MSG-3 followed for many military and civilian aircraft
• Nowlan & Heap, RCM, 1978
• SAE standardized RCM requirements for industrial equipment
with:
– JA-1011
– JA-1012
• NAVAIR standard – 00-25-403
12. The RCM Analysis Team
Officer or Chief
Maintenance
Officer
or Chief
Maintainer
13. The RCM Process
• Disciplined and highly structured
• Synergy created by the multifunctional team
• Collective wisdom of team members from all areas
– Operations
– Maintenance
– Engineer
– Logisticians
– Specialists
• Decisions based upon consensus
• Cross functional information sharing leading to
deeper understanding of the asset by all
14. Seven Questions in RCM Process
1. What are the functions and associated performance
standards of the asset in its present operating
context?
2. In what ways does it fail to fulfill its functions?
3. What causes each functional failure?
4. What happens when each failure occurs?
5. In what way does each failure matter?
6. What can be done to predict or prevent each failure?
7. What should be done if a suitable proactive task
cannot be found?
15. 1. Functions
• What are the functions and associated performance
standards of the asset in its present operating context?
– What do its users want the asset to do?
• Primary function – the main purpose the asset was acquired.
• Secondary functions
– Safety - Comfort
– Environmental - Appearance
– Control - Protection
– Containment - Economy/efficiency
– What is the Operating Context?
• Where, when, under what conditions
– What are the required performance standards?
• How much; how fast
16. Sample Function Statement
• PRIMARY FUNCTION - To pump water from tank X to tank
Y at not less than 800 gallons per hour at temperatures
ranging from 40 degrees F to 120 degrees F.
• SECONDARY FUNCTION - To contain water within the
pump, not permitting leaks exceeding 1 ounce per 8 hour
work shift
• SECONDARY FUNCTION – To prevent any contamination
at all of the water from lubricating oil.
• SECONDARY FUNCTION – To shut off automatically if the
water in tank Y rises above 90% capacity to prevent
overflow
19. 2. Functional Failures
• In what ways does it fail to fulfill its functions?
• “Failure” – The inability of any asset to do what its users
want it to do
• “Functional Failure” – The inability of an asset to fulfill a
function to a standard of performance which is
acceptable to the user.
– Performance standard must be agreed to by all stakeholders
• Total failure – fails to pump any water at all
• Partial failure – pumps water at less than 800 GPM
– Partial failure will likely be caused by different failure modes
than total failure
– Partial failure is not the same as deterioration
– Asset may fail by breaching either upper or lower limits
22. 3. Failure Modes (FMEA)
• What causes each functional failure?
• Failure mode statements should contain a noun and
a verb
– “Bearing seized” or “impeller worn”
– Not “broken,” fails,” or “malfunctions”
• Ineffective Failure Mode statements lead to
unproductive failure management techniques
– P: Number 3 engine missing.
S: Engine found on right wing after brief search.
– P: Aircraft handles funny.
S: Aircraft warned to straighten up, fly right, and be
serious.
– P: Something loose in cockpit.
S: Something tightened in cockpit.
23. 3. Failure Modes (FMEA)
• All maintenance is managed at the Failure Mode
level
– Reactive maintenance identifies failure modes after
the fact
– CBM requires that all potential failure modes be
identified beforehand in order to monitor, measure
and manage them
• Categories of failure modes
– Decreasing capability
– Increase in desired performance
– Initial incapability
25. 4. Failure Effects (FMEA)
• What happens when each failure mode occurs?
– Evidence of failure
– What threat to safety or environment
– How does it affect operations
– What damage is done by the failure
– What must be done to repair the failure
• Consider “down time” vs repair time when measuring
effects
• Best sources of FMEA data are the users who work
with the asset daily
26. 5. Failure Consequences
• In what way does each failure matter?
– How and how much does each failure matter
• Major consequences require great effort to
avoid, eliminate or minimize consequences
• Minor consequences may be run to failure
• Hidden failure requires special treatment
– Consequence could be a multiple failure
• Protected function fails while the protective
device is in a failed state
32. 7. Failure Management Techniques
• What if a suitable predictive or preventive
task cannot be found?
– Default actions
• Failure finding
– For hidden failures of protective devices
• Run to failure
• Redesign
33. Outcomes of RCM Analysis
• Revised maintenance schedules and practices
• Revised Operating procedures
• Recommended Engineering Changes
• Database of maintenance requirements
– Useful to provide documentation for decisions
• Analysis team members gain a deeper understanding
of the asset
34. Failure Mode Effect Analysis (FMEA)
STEP 1: Review the process
Use a process flowchart to identify each process component.
List each process component in the FMEA table.
If it starts feeling like the scope is too big, it probably is. This is a
good time to break the Process Failure Mode and Effects Analysis into
more manageable chunks.
STEP 2: Brainstorm potential failure modes
Review existing documentation and data for clues about all of the
ways each component can failure.
The list should be exhaustive – it can be paired down and items can
be combined after this initial list is generated.
There will likely be several potential failures for each component.
STEP 3: List potential effects of each failure
The effect is the impact the failure has on the end product or on
subsequent steps in the process.
There will likely be more than one effect for each failure.
STEP 4: Assign Severity rankings
Based on the severity of the consequences of failure.
35. Failure Mode Effect Analysis (FMEA)
STEP 5: Assign Occurrence rankings
Rate the severity of each effect using customized ranking scales as
a guide.
STEP 6: Assign Detection rankings
What are the chances the failure will be detected prior to it occurring.
STEP 7: Calculate the Risk priority number (RPN)
Severity X Occurrence X Detection
STEP 8: Develop the action plan
Decide which failures will be worked on based on the Risk Priority
Numbers. Focus on the highest RPNs.
Define who will do what by when.
STEP 9: Take action
Implement the improvements identified by your Process Failure
Mode and Effects Analysis team.
STEP 10: Calculate the resulting Risk Priority Number
Re-evaluate each of the potential failures once improvements have
been made and determine the impact of the improvements
