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An analytical process to determine the appropriate failure

management strategies to ensure safe operations and cost-wise

readiness .

RCM analysis provides a structured framework for analyzing the functions

and potential failures for a physical asset (such as an airplane, a

manufacturing production line, etc.) with a focus on preserving system

functions, rather than preserving equipment.

RCM is used to develop scheduled maintenance plans that will provide an

acceptable level of operability, with an acceptable level of risk, in an

efficient and cost-effective manner.

1.Define of RCM

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RCM ensures that:

The right maintenance is performed

At the right time

By the right people

In the right way

With the right training and tools

Benefits of RCM

If performed properly, RCM will: Maximize safety and environmental health

Depending on objective:

Reduce overall maintenance cost

Improve realized reliability/availability Provide a documentation trail for maintenance program changes

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History of RCM

1965: Studies show scheduled overhaul of complex equipment has little or no effect on in-service reliability

1967-68: Airline and manufactures form Maintenance Steering Group (MSG) and produce

MSG 1, Handbook: Maintenance Evaluation and Program Development. First applied to

Boeing 747

1970: MSG handbook updated to MSG-2, Airline/ Manufactures Maintenance Program

Planning Document. Applied to L-1011 and DC-10

1972: MSG-2 techniques applied to NAVAIR systems (P-3A, S-3A, and F-4J)

1975: NAVAIR applied Analytical Maintenance Program to Naval aircraft and engine

programs, using MSG-2 type logic (NAVAIR 00-25-400)

1978: Department of Defense (DOD) sponsored DOD report AD-A066579, Reliability

Centered Maintenance by Nowlan and Heap - Updates MSG-2 approach

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History of RCM

1983: MSG-3 issued. Used in design of Boeing 757 and 767 aircraft. Added emphasis on

structural inspection programs. Similar to RCM, but lacked guidance on interval

determination

1985: US Air Force (USAF) issued MIL-STD-1843, RCM Requirements for Aircraft, Engines

and Equipment- Similar to MSG-3 (Cancelled without replacement in 1995, USAFInstructions contain current policy/guidance)

1986: NAVAIR issued MIL-STD-2173, "RCM Requirements for Naval Aircraft, Weapons

Systems and Support Equipment". Superseded MIL-HDBK-266 & NAVAIR 00-25-400

1999: SOCIETY OF AUTOMOTIVE ENGINEERS (SAE) issued SAE JA1011, Evaluation Criteria

for RCM Processes - establishes criteria for RCM processes (NAVAIR and Aladon/John

Moubray major contributors)

2002: SAE issued SAE JA1012, A Guide to the RCM Standard - amplifies and clarifies key

concepts and terms from SAE JA1011

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RCM seven questions

The RCM method has got seven basic questions that must be fulfilled, inorder to determine if it is a true RCM method. Thats due to the fact that theRCM method is a SAE standard (JA1011 12). The seven questions are listedbelow:

What are the functions and associated desired standards of performance ofthe asset in its present operating context (functions)?

In what ways can it fail to fulfill its functions (functional failures)?

What causes each functional failure (failure modes)?

What happens when each failure occurs (failure effects)? In what way does each failure matter (failure consequences)?

What should be done to predict or prevent each failure (proactive tasks andtask intervals)?

What should be done if a suitable proactive task cannot be found (defaultactions)?

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Set level of analyze

When the decisions have been made that a RCM analysis should be done,there are two questions that must be answered:

At what level should the RCM method be conducted?

Should the whole plant be analyzed, if not, how are selections made?

Create a component list

After taken the decision of what to analyze, a component list should be done.The list consists of basic aid to the RCM analysis. The basic aid can consist ofinformation about the selected system, drawings, and pictures, schedules ofpipes or electric components. The component list could both be formal orinformal, depending on the situation.

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Information about RCM 7 steps

The RCM method consists of seven basic questions

1. Function

The first step of the RCM analysis is to define the function of each chosen

system.

2. Functional failure

A functional failure, occurs when the system is unable to fulfill its function, to

an accept level of performance set by the user. This type of failure isnt onlyconcerning the loss of a single function; its also loss of partial failures thatcould influence the production .

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3. Failure mode

When all possible functional failures have been recognized, the analysis willproceed.

The next step in the analyze process is to identify all kind of reasonable causes,that make a functional failure happen. This goes under the name failure mode.Under this step, all kinds of failure are represented, There are many types offailure modes, often from wear and fatigue.

4. Failure effects

Failure effects is the fourth step in the RCM process, and it describes whathappens when each failure mode occur. This step is in close relationship with

the next step and it should support the analyst to find out the following:

In what way the failure is a threat to safety or the environment.

In what way the production or operations are at risk.

What physical damage is caused by the failure?

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5. Failure consequences

In a maintenance organization, there can be over thousands of different failure modes.Each of these failures effect the organization in the same way, but in each case, the affectis different. They may affect personal safety, environment, product quality, productionand operation capabilities.

The RCM processes have four categories of failure consequences:

Hidden failure consequences

Safety and environmental consequences

Operational consequences

Non-operational consequences

The RCM processes are using these four failure consequences to increase the safety inthe organization. The failure consequence also helps the user to realize that there areseveral ways to managing failures.

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A SIGNIFICANT FUNCTION

Is one whose failure will have adverse effect on the end item with respect to:

Safety

Environmental Health

Operations Economics

The significant functions that were identified by the SF Selection Logicundergo further analysis as they are subjected to the RCM Decision Logic. The

RCM Decision Logic is used to determine what type of action would beappropriate to either eliminate or lessen the consequences of functionalfailures. Every function has one or more failure modes.

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SF Selection Logic Diagram

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6. The RCM task selection process

After finishing step five in the RCM process, its time for step six and the task selection.The RCM method uses a logic decision tree, in the form of a flow chart. For each step inthe process, a logical question must be answered, yes or no. After ending the selectionprocess, the RCM method will give some proposed maintenance tasks.

After that, its up to the analyst to compare the result from the RCM task selectionprocess with todays maintenance, failure and operational history. From that analysis,some new solutions of proactive maintenance tasks will come out.

7. Default actions

If no proactive maintenance task has been found, a default action must be done. TheRCM method has got three major categories of default actions, these are:

Failure finding

Redesign

No scheduled maintenance

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14/18Figure 7-1 Reliability Centered Maintenance (RCM) Decision Logic Tree

YESNO

YESNO

YESNO

YESNO

YESNO

NO YES

NOYES

Will failure of the facility or equipment items have a

direct and adverse effect on safety or critical mission

operations?

Redesign

Is the item

expendable?

Can redesign solve the problem permanently and

cost effectively?

Is there a PT&I technology (e.g., vibration testing or thermograph) that will

monitor condition and give sufficient warning (alert/alarm) of an impending

failure?

Is PT&I cost and priority-

justified?

Is there an effective PM task that will minimize

functional failures?

Accept risk Install redundant units) Define PM task and schedule Define PT&I task and schedule

Construction/ Commissioning

Is establishing redundancy cost- and

Priority-justified?

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7.1 Failure finding

The failure finding tasks involve checking, whether something is still working. Failure finding applies only to hidden or not revealed failure systems.

7.2 Redesign

The redesign is what it sounds like, redesign of systems, reconstruction ormodification. Redesign is done to the hardware that doesnt fulfill therequirements set by the organization. The redesign is expensive and istherefore used as a last resort, if the problems affect the operation performancein a negative way.

7.3 No scheduled maintenance

The no scheduled maintenance is most used when the failure is evident, anddoes not affect safety or the environment. The components are left in operationuntil they are either replaced or repaired, in other words they run-to-failure.

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The RCM process

The RCM method has previously been described in detail and its quite extensive.

Therefore the image below can clear out some difficulties about the path the RCManalysis takes during its analyze steps.

Outcome of the RCM method

The RCM method can give the following results:

Maintenance schedules

Some suggestions of possible redesign items. The need for redesign is the finalsolution if an item cannot deliver its desired performance.

The RCM method also brings some positive aspects, which are:

Improved operational performance

Lower maintenance costs

Longer lifetime of expensive items

Higher personal- and environmental safety

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The RCM process

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Thanks

Prepared by : Moamen Sayed Taha