Maintenance practices have long focused on time based "preventive maintenance" techniques. Components were changed out and parts replaced based on how long they had been in place instead of what condition they were in. A reliability centered maintenance (RCM) program seeks to offer equal or greater reliability at decreased cost by insuring only applicable, effective maintenance is performed and by in large part replacing time based maintenance with condition based maintenance. A significant portion of this program involved introducing non-intrusive technologies, such as vibration analysis, oil analysis and I/R cameras, to an existing labor force and management team

Pete, Robert R.

Tuttle, Raymond E.

English

NASA Technical Reports Server

|IMPLEMENTING A RELIABILITY CENTERED MAINTENANCE PROGRAM AT
NASA'S KENNEDY SPACE CENTER
Raymond E. Tuttle and Robert R. Pete
EG&G Florida
BOC-035
Kennedy Space Center FL 32899
(407) 867-5705
Abstract: Maintenance practices have long focused on time based "preventive
maintenance" techniques. Components were changed out and parts replaced based on
how long they had been in place instead of what condition they were in. A reliability
centered maintenance (RCM) program seeks to offer equal or greater reliability at
decreased cost by insuring only applicable, effective maintenance is performed and by in
large part replacing time based maintenance with condition based maintenance. A
significant portion of this program involved introducing non-intrusive technologies, such
as vibration analysis, oil analysis and I/R cameras, to an existing labor force and
management team.
This paper discusses what is involved in an RCM program and how EG&G is
implementing it at Kennedy Space Center on the facilities maintenance program. It
discusses technical tools, management tools and people issues involved in achieving the
goal of "better, faster, cheaper" in the facilities arena.
Key Words: Maintenance; Metrics; RCM; Reliability
The maintenance program is an integrated, closed loop, continuous improvement process
that includes life cycle maintenance planning, asset risk assessment, runtime, calendar &
condition based maintenance, outage coordination, facility condition assessment and cost
accounting. The maintenance program is proactive in nature, reliability centered and is a
true asset management program. Program effectiveness is measured in terms of asset
availability, reliability and life cycle cost.
An essential element in the program is the computerized maintenance management
system (CMMS) with the capability to interface electronically with subject matter
specific software such as predictive maintenance software programs for vibration
analysis. The software provides the traditional productivity and maintenance cost reports
as well as asset condition and maintenance requirements reports. It generates work orders
based on asset condition triggers and time based or usage based preplanned frequencies.
The asset inventory, with pertinent data including risk codes and RCM analysis
information, is contained in the CMMS. This enables Maintenance Engineers to trend
equipment failures for further analysis, and is the means of continually improving the
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effectiveness of the assigned levels of maintenance associated with an asset or definable
group of assets.
Components The Maintenance Program is a closed loop process that ensures continuous
program improvement. The first functional component cfthe process is an accurate
inventory of assets included in the maintenance program It is critical to know what is
being maintained and have it accurately identified in the CMMS.
Life Cycle Planning ensures the function of the assets is clearly defined, understood and
documented and maintenance requirements are planned for the designed life of the asset.
This occurs during the design process for new assets and is documented taking into
account such things as ease of access to components, minimization of special tooling,
incorporation of data for predictive maintenance condition trending, etc. Consideration is
also given to the expected life of materials specified in the design and program
maintenance requirements resulting from expiration of the materials useful life (i.e.
repainting structures on a 7-8 year cycle, replacing roofing systems on 20 year cycles,
etc.). The more routine recurring maintenance including t:reventive tasks (service,
inspections and minor repair) and predictive testing will b,: identified utilizing the RCM
methodology. For existing assets, this takes place during lhe RCM analysis.
Once the asset inventory is established and entered into the computerized information
system and the function of the individual or defined group of assets is clearly understood
and documented a risk assessment is performed. The risk assessment of the impact of a
loss of function of the asset is performed to determine the .appropriate asset risk category.
Assets fall within four basic risk categories (high, medium low or negligible) based on
the lack of ability to support mission or the cost involved should there be a loss of asset
function. This risk assessment is the first step in developir_g maintenance requirements
under an RCM methodology.
A significant component of the program in terms of cost effectiveness is the methodology
for determining maintenance requirements. The RCM philosophy is a departure from
traditional methods of determining maintenance requiremelts. RCM logically
incorporates the most effective mix of reactive, preventivq_', predictive and proactive
maintenance practices and draws on their respective streng_:hs. RCM applies the four
maintenance practices where each is most appropriate base_:l on the consequences of
failure and the resulting impact to mission. This combinatian produces optimum
reliability at minimum maintenance cost and the combined benefits far exceed those
resulting from using any one maintenance practice. RCM incorporates the principle that
any maintenance task performed must be proven to be applicable and effective.
Applicable implies that, of the competing tasks, the selected task is the most cost
effective option. Effective means that the performance of the task will prevent, mitigate
or detect the onset of a failure or discover a hidden failure that has already occurred.
DuringanRCM analysis,engineersuseadecisionlogic treeto assignthepropermix of
maintenance.Figure1.
Consider'each of the
fonowinatypemk_.
o Servicing
o Inspection/test to
verify operations or
detect hidden failure.
o Predicti_ m_temmee
task of some type to
detect detcriorntiou/
impending failure
o Repairto t_uce
probabilityof ftilure
O¢Cug_noe.
o Item _.placemento
reduce wobability of
failureoccurrence.
I
Is oneor a cornbhuttioa
of PM tasks spplicable
and costeffective for
the applicable risk
consequence?
( y!r¢; [ Nn I
Tuk(s) selected
should prevent
ftilu_ o,_urrence.
I Fdlure mode identified, iNo verifiable tedtmdazgy
or back-up avail_le
I
' Will the failure result
in • tisk Category A
incident?
YES
!
Will !_ f-lhuc _,sulu ]
in a risk Calcogy B
Tasks(s) selected must be i_cldcnt?
atqficable and costs should
be k3s than total imp_ct costs. _ ] No
I
• RCM DECISION
LOGIC TREE
mGXmSK
-Loss of lifdserious injury
.Lot, of shuttle/_yload
-LosddJumgeoft shuttlesystem
or major usembly/compouent
-l_or opemtloutt,
cuviroomcnml, or
political cou.r,cqueuccs _
I
Task(s) sctcc_.d must be [
applicable gridcostsshould I
be less than total impact costs.
Will the _ilurc result 1
in • risk Categor? C Iincident?
ArF_q | N_
I
Ftilu_fails into risk
Category D. No PM
is recommended
LOWmSK
-Minor opemioual,
environmental, or
political cotue_lu_aces
4ncoaveajence
APPLICABLE - Task wilt prr,'¢_J, mhiltte e_ detect the oes_ of t
failure of di_over • hidden ftilure tlutt haul tJready
occurred..
EFFECTIVE • Amoelg competing ¢amdidate_, the glectcd task it the
molrt colt effective option.
This decision logic tree focuses on sustaining the reliability of assets in support of a
defined mission. The RCM analysis is structured to implement the principle that no
maintenance task will be performed unless it is justified. The criteria for justification are
safety, reliability and cost effectiveness in deferring or preventing a specific failure mode.
Because RCM is reliability based, statistical analysis and conditional probabilities of
failure are important in determining the consequences of failure. The primary objective is
to maintain the inherent reliability designed into the asset. The product of the RCM
analysis is work procedures for both preventive and predictive maintenance that are
captured in the CMMS. The performance schedule is also generated in the CMMS as a
basis for initiating preventive/predictive maintenance.
The next program component, Facility Condition Assessment (FCA), is important to
maintenance engineers and managers as it provides feedback on asset maintenance
effectiveness. The FCA is an asset inspection and engineering analysis of maintenance
history, failure trends, any root cause failure analysis that might have been performed and
any open or planned work requirements. The purpose of the FCA is to validate
maintenancerequirementsidentifiedduringlife cycleplanning,reviewandrevisethe
effectivenessof theassignedmix of predictive,preventiveandreactivemaintenance,
identify anynewassetdeficienciesthatmayhavebeendetectedduring theassessment
process,reviewplannedmaintenanceworkandreviewenergyissues,if applicable.
Anotherimportantpartof theFCA is validatingthemissionof theasset.Program
requirementschangesmanytimesdriveassetmissionchanges.Whenmissionchanges
occur,the levelof assignedmaintenancemayrequireadjustmentdueto changesin asset
criticality. WeperformFCAs onafive yearcycleto coincidewith thebudgetcycle.
Knowing theassetmission,theassetmaintenancehistory,the identifiedandplanned
maintenancerequirementsandthecurrentconditionof theasset,workcanbeprioritized
andprogrammedfor performanceoverthebudgetcycle. Existingmaintenance
procedurescanbevalidatedandadjustedasrequired,monitoringprogramsimplemented
andtestsconductedonassetsto furtherevaluateanysuspectedproblems.TheFCA
providesa structuredprocessfor validating,justifying andprioritizing maintenance
requirements.
An appropriatelevelof maintenancecannotbeassignedto anassetunlessthe
consequencesof failureof that assetareclearlyunderstood.RCM forcesfocusonthe
productof a system,ratherthenon individualitemswithin a system.As aresult,many
itemswhicharecriticalto a systemoperationarefoundto havebackupsor work-arounds
designedinto thesystem,soafailureor lossof an individ_mlitemdoesno_.._tresultin a
systemfailure. An exampleof thismaybein electricpox_erdistribution,wherepowerto
aspecificfacility is critical. Thelossof thefeedercablewill resultin nopowerthrough
that cable. It will not result in a power loss to the facility, however, because the facility
has duel power feed from independent circuits, an emergency backup generator and an
UPS. The system does not fail, only the component.
Risk assessment is the first step in determining maintenance levels. Four risk levels have
been established, based on the consequences of failure; hitch, medium, low and no risk.
High and medium risk codes are often associated with cat_strophic failures, but because
of the economic impact costs smaller failures can also fall into this area. Ifa facility
suffers a loss of utilities and has no secondary feed (either onsite or portable), the people
in that building will have to stop work and leave. This "impact cost", different from a
repair cost, while not obvious to maintainers is real and m_lst be a factor in evaluating the
risk level. The RCM analysis is structured to implement tile principle that no
maintenance task will be performed unless it can be justified. The criteria for
justification are safety, reliability, and cost effectiveness in deferring or preventing a
specific failure mode. Because RCM is reliability based, statistical analysis and
conditional probabilities of failures are important in determining the consequences of
failure. The primary objective is to maintain the inherent leliability designed into the
equipment. Figure 2 graphically ties all the parts together.
INTEGRATED MAINTENANCE PROGRAM MODEL
_ 100 YEARS
DESIGN /
CONSTRUCT
ACTIVATE
I= [
< REFURB. > <REPLACE >
=1=..... dl=__
+++
+++++ +++++ +++++ +++++ + +
0 0 0 0
< > PROGRAMMED - ROOF REFURBISHMENT
- EXTERIOR STRUCTURE PAINTING
+ PREDICTIVE -THERMOGRAPHY ON PWR PANELS
-AND THE ROOF
- VIBRATION DATA ON PUMPS
* PREVENTIVE - A/C FILTER REPLACEMENT
9 RUN TO FAILURE - RESTROOM EXHAUST FANS
O CONDITION ASSESSMENT - FACILITIES / SYSTEMS / EQUIPMENT
Figure 2
In this model, it has been determined during the design that the facility is expected to
support its defined function for 100 years. The roof of the facility, given the climate the
facility will be subjected to, will require major refurbishment after approximately 20
years of service. Therefore, as part of the life-cycle plan, a major refurbishment is
identified 20 years from date of facility activation. In addition, while determining the
exterior paint specifications, historical data and engineering studies indicate facilities
require repainting every five years. This, too, is added to the life-cycle plan as identified
program level maintenance requirements. Infrared thermography is also identified on a
frequent basis. It is used to perform a condition assessment of the roof and the electrical
panels throughout the facility in lieu of previously assigned labor intensive PM tasks.
Air filters are replaced on a regularly scheduled basis.
PredictiveMaintenance,alsoknownasPredictiveTestingandInspection(PT&I), can
determinetheconditionof theequipmentandprovidevarioustrendindicators.
Interpretationof theseindicatorsallowspotentialfunctionalfailureto be forecastso
correctivemaintenancecanbeperformedto precludefailure. Workingasacomplement
to thePM programa PT&I programcan:
o Helpdeterminetheconditionof a componentand:dentifyrequiredrepairsbefore
that componentfails.
o Conserveresourcesby performingmaintenanceonanas-requiredbasisrather
thanonacalendarfrequencyor arun-timebasis.
o Minimize downtime.
The effectivenessof eachapplicablePT&I testis examinedto determinewhichtestor
combinationof testswill beused.Any testby itself maynotgivea goodrepresentation
of theoverallconditionof eachpieceof equipmenton thesystem.However,certain
combinationswill giveavery goodindicationof equipmentcondition. Comparisons
with previoustestsprovidestrenddatausefulin conditionassessmentanalysis.
Historically, thefocusof maintenancehasbeenthePreventiveMaintenance(PM)
program.Electricalandmechanicalequipmentexperiencedeteriorationovertimethat
eventuallycausesit to fail. PM is usedto slowthisdetericration,ensuringthe
equipment'soperationalife. A properlyconductedprogrzmreducesoveralloperating
costs,aidsmissioneffectiveness,safety,andassuresthecc,ntinuedpreservation,
usefulness,andperformanceof assets.ThePM program,coupledwith theother
elementsof theoverallmaintenanceprogram,allowsengineersto beawareof equipment
conditionsothatsufficienttimeis availablefor thesystem_ticplanningandschedulingof
requiredrepairwork.
Preventivemaintenanceconsistsof the planned and schedt led maintenance tasks that are
periodically performed on equipment to avoid a breakdowt_. The frequency is based on
calendar date, rate of utilization (routine), or condition which is determined by trending
data collected through the application of PT&I technologic;. The PM program consists of
the following:
o Inspections of mechanical, electrical and other phy_,ical structures, installed
equipment and systems such as motors, pumps, compressors, faucets, light switches, etc.
o Inspections are performed on a periodic, pre-deterrr_ined basis in aneffort to
determine the degree of operating efficiency and whether e luipment deficiencies exist.
o Routine servicing of equipment including lubricaticn, cleaning and changing
filters, minor adjustments and parts replacement, and condition reporting.
o Formalized evaluation and work generation system which ensures discovered,
uncorrected deficiencies are entered into the normal planning and scheduling system.
Run-to-failureisa reactivecomponentbecauseit is basedon thepremisethatno
maintenancetaskthatimprovesthereliabilityof theF/S/Ein a costeffectivemannerhas
beenidentified. Userscall a troubledeskto reportbreakdownson run-to-failureitems.
Whenthecorrectiveactionrequiredis beyondthescopeof atroublecall, if engineering
is required,or if materialmustbeordered,thetroublecall is changedto arepairwork
order. As with otherworkorders,labor,materialsandmaterialcostsaretracked in a
CMMS. This informationis thensentto a computerhistory file whichcanberetrieved
later for usein F/S/Econditionassessments,makingrepair/replacedecisions,failure
trending,andotherengineeringanalysis.
MaintenanceEffectiveness The effectiveness of the maintenance program must be
measured and validated. Long term effectiveness is monitored through the facility
condition assessment while short term effectiveness is determined using failure trending
analysis, which highlights failure trends on like equipment. This advanced notice gives
time to take action to prevent catastrophic failures.
Failure trending codes are developed by maintenance engineers with support from field
technicians. These codes are used by the technicians in the field to track and classify
failures and are recorded in the CMMS. The coding structure, coupled with existing
report filter capabilities, allows a relatively quick analysis of failure data. If a problem is
suspected, a more detailed analysis is performed. Reports provide information on the
following elements: I) number of loss-of-function events; 2) cause of loss; 3) disposition
of cause; and 4) corrective action taken.
PROGRAM MEASUREMENTS (METRICS) The following metrics are reported to
measure the progress and of cost effectiveness of the maintenance program,
a. Equipment Availability
% = Hours System/Equipment is Available to Run at Capacity
Total Hours During the Reporting Time Period
b. Maintenance Overtime Percentage
% = Total Maintenance Overtime Hours Durin_ Period
Total Regular Maintenance Hours During Period
C, Percent of Emergency Work to Routine Work
% = Total Emergency Hours
Total Maintenance Hours
d. Percent of Faults Found in Thermographic Survey
% = Number of Faults Found
Number of Devices Surveyed
e. Total cost of maintenance per year
Figure 3 shows some results obtained by the program as measured by two metrics.
33000.
32000.
31000.
30000,
_ 29000.
28000,
o 27000,
26000-
25000.
24000
III FY 94 DFY95 IIFY 96]
ACTUAL MAINTENANCE COSTS
$29
$28
$27
$26
$25
0
$23
$22
$21
$20
FY91
\
\
\
i E I I I
FY92 FY93 FY94 FY95 FY96
Lessons Learned Many of the lessons we learned are available from existing texts, both
technical and management. It is perhaps inevitable that lessons have to be learned
individually in order to be understood, and so many of the lessons presented here are of
an obvious nature. By far our biggest finding was the value of repetition. By definition,
a cycle of continuous improvement implies doing the same thing over and over and
getting a bit better each time. Implementing a reliability centered maintenance program
involves changing the way people think and work. Training, explanations, briefings,
analysis, making changes and tracking results were done on an individual basis, shop by
shop. Selecting a visible, intuitive initial technology is also an important point. Laser
alignment was easily demonstrated, learned and understood; vibration monitoring is more
involved and less readily grasped. I/R cameras are so advanced the operation is simple;
point and shoot technology allows anyone to actually see the temperature difference
between a loose connection and a proper one. As we were able to show results, we began
to build a cadre of supporters who functioned as champions in their own right.
When we began this project, we went through a developmental phase, an implementation
phase and are now in an operational mode. It is no longer a phase - we have achieved a
shift in the way we do business. The very nature of the process ensures it will repeat
itself over and over - a cycle of continuous improvement. This program is not something
we do - it is a way of getting things done in an efficient, cost effective and risk
appropriate manner.
Acknowledgments
This work is supported by the Kennedy Space Center of the National Aeronautics and
Space Administration.



Implementing a Reliability Centered Maintenance Program at NASA's Kennedy Space Center

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