Rcm 4 hour overview for rcm teams

1

RCM Reliability

Centered

Maintenance

Overview for RCM Teams

x

2

RCM Overview for RCM Teams

Reliability

Centered

Maintenance

x

3

• Based on Reliability Centered Maintenance

Concepts

• Proven Technology

• Provides a structured approach to

establish a Maintenance strategy

x

4

• Provides a strategy for stocking

spare parts

• Provides an easy way to track

implementation of an RCM analysis

x

5

Course Outline

I. RCM History

II. Principles of RCM

III. Maintenance Tasks

IV. Understanding Failure

•Failure Patterns

•Effective Maintenance Tasks

for each pattern

x

6

V. RCM process steps

•Operating Context

•Primary and Secondary Functions

•Functional Failures

•Failure Modes

•Probability Rating

•Failure Effects

•Consequence Rating

VI. Case study x

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Reliability Centered Maintenance

History

• 1974 - United States Department of

Defense commissioned United Airlines

to report on the maintenance process used

in the aviation industry

• Conducted by

• Stanley Nowlan

• Howard Heap

x

8

Reliability Centered Maintenance

History

• At this time the airline industry was using a high

amount of redundant systems combined with

scheduled discard and scheduled restoration tasks

to ensure safety

• Records showed that the maintenance tasks had little

or no effect on the reliability of the aircraft. In fact

some of the maintenance was shown to be

intrusive, and could cause failures.

• Today RCM remains the process used to

develop and refine aircraft maintenance

x

9

x

Principles of RCM

•What Function does this machine serve?

•What is the Functional Failure?

•How does the Failure occur?

•What are its Consequences?

•What can be done to PREVENT the Failure?

•What can be done to reduce the

Consequences of a failure?

10

MAINTENANCE:

Focus on equipment performance

ensure physical assets continue to fulfill their

intended function

improve equipment performance to meet

business needs

performed in a cost effective mannerx

11

•The objective of RCM is to use existing

process knowledge to develop a

maintenance program that will maximize

equipment up time. (Reliability)

• RCM looks to accomplish this by applying

a series of questions to a modified

FMECA (Failure Mode Effect and

Criticality Analysis).

x

12

• Maintenance tasks tend to fit in one of

five categories

•On Condition Tasks - or Condition Monitoring

•Restoration Tasks - restore equipment to its

original state

•Discard Tasks - complete replacement of

a component

•Failure Identification Tasks - operating

check of hidden functions to ensure

they work when needed

•Redesign Tasksx

13

Understanding Failures

• In order to set up the proper maintenance

for a piece of equipment or component

you must first understand how it fails.

• RCM requires an understanding of six

failure patterns and designs a maintenance

program using techniques best suited

for each patternx

14

A

B

C

D

E

F

Failure

Patterns

x

15

A

Pattern A

•Commonly referred

to as a bath tub curve

•For many years this was thought to be the

only failure pattern for equipment.

•We now know it is really a

combination of separate failure

patterns

x

16

A

• This failure pattern

shows early life failure followed,

by a period of random failure, until it reaches an

age where it becomes rapidly more prone to

failure.

• 4% of the failures in the Nowlan and Heap

study fit this failure pattern

• On-Condition monitoring is the preferred

maintenance strategy.

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•An age limit may be an effective maintenance

strategy, provided a large percentage of units

survive to the age at which wear-out begins.

• Simple electromechanical systems fit this failure

pattern.

A

18

BPattern B

•Shows age related failures where a

component has a low level of random

failures, until it reaches an age where it

becomes rapidly more prone to failure.

x

B• 2% of the failures in the

Nowlan and Heap study fit this pattern

• On-Conditioning monitoring is the preferred

Maintenance strategy.

• Scheduled Discard or Restoration may also be an

effective maintenance strategy.

• Aircraft reciprocating engines fit this failure

pattern - belts, sheaves, chains, sprockets, and

impellers are other examples19

20

CPattern C

•Shows a steadily increasing probability

of failure but no one point where we can

say it reaches an age where it becomes

rapidly more prone to failure.

• 5% of the failures in the Nowlan

and Heap study fit this failure

pattern x

C• On-Condition monitoring

is the preferred

maintenance strategy.

• Scheduled Discard or Restoration may also be an

effective maintenance strategy. It depends on the

cost of downtime in comparison to the cost of

component replacement.

• Aircraft turbine engines fit this pattern. Other

examples of Pattern C components are Pipes,

Tires and Clutches.

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22

DPattern D

• This failure pattern shows that the

equipment starts up and runs for a short

time with no failures, increasing quickly

over a short period of time, to a consistent

level of random failures.

x

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D• 7% of of the failures

in the Nowlan and Heap study fit this pattern.

• On-Condition monitoring is the preferred

maintenance strategy.

• Hydraulics and pneumatic components fit this

failure pattern.

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EPattern E

• Random failure pattern, the probability

an item will fail is the same at any given

point.

• Ball bearings are an example of a failure

pattern E component

x

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E• 14% of the failures

in the Nowlan and Heap study fit this failure

pattern. ( Exponential Survival Distribution )

• More recent studies indicate failure rates between

42% and 72%.

• On-Condition monitoring is the preferred

maintenance strategy.

• Time based maintenance is not effective

in reducing these failures.

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FPattern F

• Early life failure pattern, the probability

of failure declines with age. The highest

probability of failure occurs when the

equipment is new.

• Electronic components are an example

of this failure patternx

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F• 68% of the failures

in the Nowlan and Heap study fit this pattern.

• More recent studies indicate failure rates between

16% and 29%.

• Look to solve early life failures by using

“burn-in” techniques.

• If failure rates are too high, explore

redesign possibilities.

A

B

C

D

E

F x

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4% On-Condition Task

2% On-Condition Task

Scheduled Discard Task

Scheduled Restoration Task

7% On-Condition Task

65% On-Condition Task

17% On-Condition Task

Redesign Task

Industry today

5% On-Condition Task

Scheduled Discard Task

Scheduled Restoration Task

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The RCM Process

The RCM process is structured and interactive, it

takes the combined effort of a cross functional team

to complete the RCM process.

The remainder of this course will use a case study to

simulate how the RCM process flows

and demonstrates the outputs of an RCM

analysis.

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The RCM Process

We begin the RCM process by writing a

formal Operating Context for the machine

we are analyzing.

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The RCM Process

The Operating Context will clearly describe:

• Why the asset exists

• When it was purchased and installed

• What the expectations are of this process

• The consequences of unscheduled downtime

• The present condition and performance

of this process

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The RCM Process

Describing Primary and Secondary functions

With an Operating Context and process

drawings, the RCM team can now begin to describe the

machine functions.

The first function of any machine is the Primary Function

The remaining machine functions are know

as Secondary Functions.

The RCM Process

Describing Primary and Secondary functions

The Primary Function is the major reason why an

asset exists. A primary function should include the

following:

• Performance Standards

• Quality Standards

• HSE Standards

“Think about - What you have when the process starts,

and what you want when the process is finished.”

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Describing Primary and Secondary functions

The RCM Process

While the primary function is the reason an asset exists,

it is important to list the remaining Secondary Functions.

Secondary functions are often less obvious, but should be

considered just as crucial as the primary function.

Secondary functions can be active, such as to be “To be

able to pump”, or passive as in “To be capable of

relieving an over pressure condition”.

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The RCM Process

Describing Primary and Secondary functions

Examples of Secondary Functions:

• To be able to contain fluid in a gear box.

• To be capable of shutting down the machine in the event

of and emergency.

• To be able to support the mixer

• To be able to provide visual indication

• To be capable of protecting personnel from

rotating equipment.

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Class Exercise

•Read the Operating Context for the Methanol

Unload System

•List the primary function and three secondary

functions.

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Methanol Unload System Operation Performance Statement

The methanol unload system is located at building Z Kodak Park. The pumping

system was designed to unload methanol from a tractor trailer tanker to a holding tank. It

was purchased and installed in 1995. The unload system was designed and installed for

off loading full and partial loads of methanol. The holding tank is a 20,000 gallon

stainless steel tank mounted inside a sealed concrete vault and surrounded by pea -gravel.

The holding tank has a level float that provides continuous level readings and a high level

shutdown at 18,000 gallons. Level alarms warn the operator in the control room with a

light on the control panel, an audible bell and a message on the CRT. A high level

condition will shut down the pump, it will be able to restart when the level drops below

13,000 gallons. The emergency high level device is a high level probe set at 19,000

gallons. The emergency high level probe will alarm and shutdown the entire system, it

will not be able to restart without operator intervention. The concrete vault is designed

for environmental protection should the tank overflow, or leak. There is a Solvent Vapor

Detector located inside the vault, it is capable of detecting minute amounts of vapor.

Approximately a one quart spill will trigger the detector, the entire system will be shut

down. The trailer unload pump is a stainless steel centrifugal pump. The designed flow

and pressure of the pump are 120 GPM at 70 PSI. The pump is isolated by hand valves

on either side and protected by a minimum flow indicator and a pressure tap. The

minimum flow indicator must see a liquid flow of greater that 100 GPM or the pump will

shutdown after one minute of low flow condition. The pressure tap will shutdown the

pump if the discharge pressure falls below 50 PSI for more than one minute. Piping

between the pump and holding tank is 2” stainless steel and has drain valve taps before

and after the pump. Trailer wagons average 5,000 gallons and the cost of methanol is

$9.00 per gallon. Chemical spills are not tolerated at Kodak Park, leaks of more than 1

quart are reported to loss control at a minimum cost of $20,000 per incident. If a spill of

more than one quart reaches the soil outside of the concrete vault it requires a total

shutdown and clean up of the spill area resulting in at least 3 days of lost production.

Tank trucks are scheduled in at two hour intervals, starting at 7 am each day with the last

deliver at 3 pm, the average cycle time to unload is 40 minutes. If a truck is not unloaded

when the next one arrives on site, the driver calls dispatch and cancels the next delivery.

We are charged for the undelivered load at the regular rate. Any time the tank runs dry

there are consequences of catastrophic proportions.

Methanol Case Study P&ID DrawingSV3

LS3LS2

PS1

LS1

SV2

TV1SV1

FS1

SVD1Hose

Pump

DV1 DV2

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The RCM Process

Functional Failures

The next step in the RCM process is to list out the

Functional Failures for the primary and secondary

functions.

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The RCM Process

Functional Failures

Functional Failure - Is the point in time when a

process or component can no longer perform its

function at all or is unable to meet its desired

performance standard.

A Functional Failure statement includes:

• An exact performance level that defines the

point of failure.

• Is normally stated as either a total loss of functional

capability or a reduced functional capacity.

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Class Exercise

List out the functional failures for the

primary function and three secondary functions

of the Methanol Unload System.

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The RCM Process

Failure Modes

Once the Functions and Functional Failures

have been listed, we look to identify the

Failure Modes.

The Failure Mode is the specific manner or

cause of a process or component failure.

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The RCM Process

Failure Modes

Failure Mode statements should include:

• The specific component that has failed

• The specific cause of the failure

For example - Pump bearing fails due

to lack of lubrication.

The bearing is the specific component, and

lack of lubrication is the specific cause.

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Failure Modes

The RCM Process

When listing failure modes you should:

• List all failure modes that have occurred

• List failure modes that may not have

occurred but are likely to at some

point in time.

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The RCM Process

Probability Rating

Once a failure mode has been identified and

listed, we then look to assign a probability

rating to the failure mode.

The probability rating combined with

the consequence rating is used to help

us determine the criticality of a

failure mode.

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The RCM Process

Probability Rating

Probability -The likelihood that an event will happen. If there is

no maintenance history for your process, we use the experience of

the mechanics and operators to access the probability of failure.

High - The failure has happened often enough to be considered a

dominant failure mode.

Medium - The failure has happened often enough to remember

and probably will happen again.

Low - The failure has never happened or has happened

so infrequently that I can’t remember last time it did.

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The RCM Process

Failure Effects

After listing a Failure mode and defining its

probability of failure, we now can describe the

Failure Effect.

The Failure Effect is the physical effects of a failure

mode on the functional capability of the equipment.

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The RCM Process

Failure Effects

Failure Effect statements include:

• The first sign of evidence the failure has occurred

to the operating crew.

• Describe as much as possible the chain of

events that precede the failure.

• Describe the chain of events that happen

after the failure occurs

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Failure Effects

The RCM Process

Failure Effect statements include:

• The consequences resulting from the failure

• Any secondary damaged caused by the failure

• Downtime that resulted from the failure

• How often the failure occurs.

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The RCM Process

Consequence Rating

Once the failure effect has been clearly described,

the team can now assign a Consequence Rating to the

Failure Mode.

The Consequence of the failure mode is the impact

the failure has on your business -

• HSE

• Cost

• Secondary Damage

• Downtime

The RCM Process

Consequence Rating

The impact on your business, safety, environment

or cost of repair if failure occurs

High - The failure causes a loss in capacity that will adversely impact

production schedules. This failure has a direct adverse effect on HSE.

High repair cost or waste.

Medium - This failure will cause the operating department to shift schedules,

crews may have to work overtime or additional costs will be incurred to

manufacture product. This failure does not effect HSE issues.

Low - The failure has no impact on the end user customer, there is a lot of

unused machine capacity or a large amount of stored product. There is no

secondary damage resulting from this failure and no impact to HSE.

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52

Class Exercise

List out five Failure Modes that would cause you

to be unable to unload methanol at all.

- Assign a probability rating for the failure mode

- Clearly describe the effects of the failure

- Assign a consequence rating to the failure

53

Methanol Tank Farm Failure History

Component # of failures Repair Time Work around SOP's

TV1 1 0 Pump from top of trailer

Hose connector 4 0 Pump from top of trailer

SV1 failed closed 2 6 hrs

SV1 leaks by Leaking now

DV1 left open 1 72 hrs

DV2 left open 0

DV1 or 2 failed closed 0

FS1 failed closed 2 0 Rely on Pressure reading, extra operator

FS1 failed open 0

Pump seal leaking 8 6 hrs

Pump impeller 1 10 hrs

Pump motor 0

Pump motor coupling 8 30 mins

LS1 failed open 1 4 hrs

LS2 failed open 1 4 hrs

LS3 failed 0

PS1 failed low 1 30 mins Rely on Flow reading, extra operator

PS1 failed high 0

Pump bearing 1 6 hrs

Pump pipe flange seal 2 2 hrs

SVD1 failed 1 4 hrs Substitute a portable sniffer

Component Cost Lead time P/N

FS1 $4,000 6 hrs SW123

Hose coupling $150 2 hrs HC-99

Impeller $10,000 3 months IMP-345

LS1, LS2, LS3 $75 2 hrs LS-239

PS1 $350 2 hrs PS-124

Pump seal $500 2 days SEV-789

Pump bearing $400 2 hrs TMP-41

Flange seal $25 2 hrs FS-Y2K

SVD1 $5,000 75 days SVF-UALL

SV1 $35 4 hrs STV-1000

DV1 $35 4 hrs STV-1000

Pump motor coupling $35 4 hrs COUP-1

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The next step of the RCM analysis is the decision process.

It is where we determine the type of failure consequence and

the proper maintenance strategy. There are four types of failure

consequences.

• Hidden

• Health, Safety, and Environmental

• Economic

• Non-Economic

The RCM ProcessRCM Decisions

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Hidden Failures

• Have no direct consequences

• Require multiple failures to

be evident to the operating

crew

Examples:

• Safety devices

• Redundant systems

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Health, Safety and Environmental Failures

•Have a direct effect on the health & safety

of individuals or the environment

Examples:

•Leaks

•Spills

•Emissions

•Pinch points

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Economic Failures

•Direct adverse effect on Production

costs

Examples:

•Non-Conforming Product

•Yield losses

•Maintenance cost

•Operating Costs

•Parts costs

58

The RCM ProcessDetermining the correct Maintenance Strategy

In working our way through the decision process, the

final step is to determine the correct maintenance

strategy and interval.

• Predict the failure is about to occur

• Prevent the failure from occurring

• Reduce the consequences should the failure

occur.

• Redesign to eliminate the failure

This requires an understanding of the different

types of maintenance.

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Types of Maintenance

•On Condition - Inspection, measurement

observation, non-destructive task for parts prone

to failure. (Predictive)

•Restoration -Once the end of useful

life is reached, you restore the component

to “like new” condition (Preventive)

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•Discard - Once the end of Useful Life is

reached, you remove and replace the component.

(Preventive)

•Failure Identification - Inspection for

undetected failure of components not used

during normal operation (Consequence

reduction)

Types of Maintenance

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On-Condition Monitoring

Traditional methods

• Vibration analysis

• Lubrication analysis

• Thermography

• Motor Circuit Evaluation

• MCEmax testing

• Ultrasonic testing

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Contemporary methods

Process Monitoring

• Temperature

• Pressure

• Electrical Current

Statistical Techniques

• Trend Charts

• Control Charts

On-Condition Monitoring

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Informal methods

•People’s senses

• Daily walk around

• Cleaning

• Listening

• Visual observations

• Smell

• Touch

On-Condition Monitoring

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RCM Maintenance Intervals

• For scheduled discard and restoration

tasks

• Are determined by knowing the

“Useful life” of the component

65

MTBF

Useful

Life

Time

Nu

mber

of

Fai

lure

sUseful Life Failure Chart

x

66

RCM Maintenance Intervals

For On-Condition Tasks

• When setting up tasks for On-Condition

maintenance, use the P-F interval of the

failure.

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Typical Failure Curve

P

F

P-F Interval

P - The point in time when failure

begins

F - The point in time when

equipment can no longer

deliver it’s primary function

x

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P

F

Ball Bearing

PF Curve

12

3

4

5

6

7

Time

Perfo

rman

ce Lev

el

69

P

F

1 23

4

5

6

7

Time

Perfo

rman

ce Lev

el Reaction

Time

Ball Bearing

PF Curve

70

P

F

1 23

4

5

6

7

Time

Perfo

rman

ce Lev

el

Reaction

Time

Inspection

Interval

1/2

Ball Bearing

PF Curve

71

MTBF (Mean Time Between Failure)

is not valid or useful in determining

Maintenance task intervals.

x

72

• When determining maintenance task

intervals, the team should be conservative,

when data for failure history is not available.

• Tasks should be cost effective.

73

Class Exercise

•Run each of your failure modes through the

RCM decision and Spare Part Flow Charts

•Determine the correct task and interval

•Determine the correct spare part strategy

Will failure

be detected

while the operator is

performing their

normal

duties?

Will this

failure on its

own effect

HSE?

Will

this failure

have operational

(economic)

consequences?

Is there

a failure finding

task that would

detect

the failure?

NO

START

YES NO

No scheduled

maintenance

required

NO

Establish a

failure finding

task

YES

Is there

any early warning

the failure is going

to occur?

YES

Is there an

on-condition task

that is applicable

and cost effective?

YES

Is there a

scheduled rework or

discard task that

would reduce the

failure rate?

NO

Is this task

applicable and

cost effective?

YESNO

YES

Redesign of the

1. Equipment

or

2. Procedures

or

3. Process

is

REQUIRED

NO

NO

Implement a

preventive

maintenance task

(Scheduled

rework or

discard)

YES

Does this

failure effect

HSE?

Consider

Redesign of the

1. Equipment

or

2. Procedures

or

3. Process

to reduce

consequences to

an acceptable

level

NO

NO

YES

YES

YES

NO

YESNO

Implement

predictive

(on-condition)

maintenance task

YES

NO

NO

YES

Implement a

preventive

maintenance task

(Scheduled

rework or

discard)

Is there a

business case for

a redesign?

Redesign

No scheduled

maintenance

required

(Consequence

reduction strategy )

YES

NO

Implement

predictive

(on-condition)

maintenance task

Reliability Centered Maintenance Decision Flow Chart

Is there a

scheduled rework or

discard task that

would reduce the

failure rate?

Is there

any early warning

the failure is going

to occur?

Is there an

on-condition task

that is applicable

and cost effective?

Is this task

applicable and

cost effective?

Risk

Consequence

Hig

hN

eglig

ible

Negligible Low Medium High Extensive

Spare Parts Risk Matrix

Do

Not

Stock

Part

Stock

The

Part

Risk

CONSEQUENCENegligible - *No impact on production

*No HSE risk*No impact on process

Low * No impact on production* No HSE risk* Some impact on process

Medium * Some impact on product* Some impact on process* No HSE risk

High * Unacceptable product* Failed process* HSE risk

Extensive * Defective product to Customer* Loss of this machine shuts down

a customers process* Someone will be injured

Formula :Part Stocking Cost = Purchase price + (.30 X Purchase price

X yrs of no use)W aiting For Parts Cost = Out of pocket cost per hr X Lead time

in Hrs waiting for part

PROBABILITYNegligible - can not imagine this ever happeningLow - can not remember the last time it happenedMedium - happens occasionallyHigh - happens often

DO NOT STOCK THE PART - The risk of not stocking the part is low

RISK - The risk factor varies based on many local decision points. If your business has a high risk tolerance, do not stock the part. If your business has a lowrisk tolerance, stock the part

STOCK THE PART - The part can be stocked as an LMSC, minus one, Stock 1, Sub-stock room, or KSC stock. Pick the option that suits your needs.

Spare Parts Risk/Cost Decision Model

START

Is there anyearly warning thefailure is going to

occur?

Can areplacement part

be acquired beforethe failure

occurs?

Is therea known age atwhich the part

fails?

Does waitingfor part to be

delivered cost morethan Stocking

Part ?

Do notStock Part

Yes

No

Yes

Ispart already

stocked?

Look for areplacement part

or redesign

Continue toStock Part

Yes

No

No

No

Yes

No

Yes

Yes

Is partObsolete?

NO