Download - 20_RAMS_03

7/17/2019 20_RAMS_03

http://slidepdf.com/reader/full/20rams03 1/22

RAMS-CONMANAGEMENT CONSULTANTS

Loitersdorf 15 D-85617 Assling Tel +49 8092 7082 77 Fax +49 8092 7082 85 [email protected] 31, 2000 of 22

Wolfgang Ansorge

R eliability

AvailabilityMaintainability

Safety

InScientific-

Technical

ProjectsJanuary 2000

7/17/2019 20_RAMS_03


RAMS-CON RAMS in Scientific-Technical Projects

MANAGEMENT CONSULTANTS


Table of Contents

TABLE OF CONTENTS ................................................................................................2

1 SCOPE .......................................................................................................................... 3

2 INTRODUCTION ........................................................................................................ 3

3 DEFINITIONS..............................................................................................................5

4 APPLYING RAMS TECHNOLOGIES TO SCIENTIFIC-TECHNICAL

PROJECTS..................................................................................................................6

4.1 BASIC CONSIDERATIONS ..........................................................................................6

4.2 PHASING OF RAMS ACTIVITIES ...............................................................................7

4.2.1 Organisational Aspects ....................................................................................9

4.2.2 Concept and Definition Phase..........................................................................94.2.3 Design and Development Phase ( Final Design Phase)................................. 13

4.2.4 Manufacturing Phase..................................................................................... 16

4.2.5 Installation Phase .......................................................................................... 18

4.2.6 Operation and Maintenance Phase ................................................................20

4.3 DISPOSAL PHASE....................................................................................................22

7/17/2019 20_RAMS_03





1 Scope

This document is intended to supply additional information to a lecture on the subject

“RAMS in Scientific-Technical Projects” held at CERN in the framework of the Academic

Training Programme. It was prepared to give an introduction to the relevance and the

application of RAMS management and engineering processes to projects related to the

acquisition and operation of technical facilities and equipment needed to facilitate

scientific research projects.

The goal of the author is to attract the attention of the scientists, managers and engineersinvolved in these kinds of projects to a modern, state of the art technology, and to

encourage them to apply this technology also in their projects as a means to optimise thefacilities’ and equipment’s functionality and to achieve the scientific goals most efficiently

and at affordable costs.

Since it is the authors’ personal interest to promote and foster the application of the RAMS

technology in new scientific-technical projects and those already under execution, and to

already existing facilities and equipment, the booklet may be copied or otherwise

distributed without any special agreement by the author.

2 Introduction

The term RAMS stands for all aspects concerning the

Ø R eliability

Ø Availability

Ø Maintainability, and

Ø Safety

performance characteristics of a product, whereby the term “product” is used in this

booklet as synonym for systems, subsystems, equipment etc.

The RAMS characteristics of a product determine essential parameters of the product suchas the user satisfaction, the usability and acceptability of the product, the operation and

maintenance costs, and last not least the users’ safety and health risk when operating the

product.

The RAMS technology is a recognised management and engineering discipline for the

purpose to guarantee the specified functionality of a product over its’ complete live

cycle, and to keep the operation, maintenance and disposal costs at a predefined

accepted level, by establishing the relevant performance characteristics at the

beginning of the procurement cycle, and by monitoring and control of their

implementation throughout all project phases.

7/17/2019 20_RAMS_03





Despite the fact that the basic RAMS technologies were already established nearly a

generation ago, the attempt to achieve high level reliability, availability, maintainability

and safety was in the past very often limited to the aerospace and military industries and tocomplex industrial systems. Today the world-wide competition, the increasing system

complexity leading to high investment and operation and support costs, and the decreasingfinancial budgets promote the wider distribution of the RAMS technologies and their

application also by industries reluctant in the past to apply these resources and efforts

saving techniques.

The RAMS characteristics are by their very nature closely connected with each other. For

an unreliable product the maintenance support and the number of necessary maintenance

activities will be high in order to keep the product in an operational condition and available

for its intended use. Failures of the product or hazardous maintenance operations may

impair the operators’ health and safety. Modifications of one of these characteristics in anydirection have an immediate impact on the other three RAMS characteristics.

Predetermining and influencing the RAMS performance characteristics of a product during

its design and development phase is quite a frequently used method in commercial serial

production industries, to influence the products’ lifetime, the production costs and thereby

indirectly also the production quantity and the profit the company makes with that specific

product, e.g. the lifetime of washing machines is perfectly controlled, and spare parts and

maintenance activities are main income sources for car manufacturers and service stations.

RAMS performance characteristics not only influence the life cycle costs and usability of

the commercial serial products. They are equally important to facilities and equipment of scientific research programmes, where the achievement of the scientific goals and the

efficiency of the research programme depend to a large extent on the high availability of

the facilities and equipment at affordable costs.

7/17/2019 20_RAMS_03





3 Definitions

In the following some basic definitions and explanations are given to create a common

basis for the understanding of this document.

• Acquisition Phase : The first part of the product life cycle covering the

- Concept and Definition Phase

- Manufacturing Phase, and the

- Installation Phase

• Availability (performance)1: The ability of an item to be in a state to perform

a required function under given conditions at a given instant of time or over agiven time interval, assuming that the required external resources are provided.

Note: there are two types of availability, the inherent availability of a product

and the operational availability.

Inherent Availability2: Inherent availability reflects the percentage of time a

product would be available if no delays due to maintenance, supply, etc. (i.e.,

not design-related) were encountered.

MTBF is the mean time between failures, and MTTR is the mean time to repair

Operational Availability: Operational availability is similar to inherent avail-

ability but includes the effects of maintenance delays and other non-design

factors. The equation for operational availability Ao is:

where MTBM is the mean time between maintenance, and MDT is the mean

downtime.

Note that MTBM addresses all maintenance, corrective and preventive, whereas

MTBF only accounts for failures. MDT includes MTTR and all other time

involved with downtime, such as delays. Thus, Ao reflects the totality of the

inherent design of the product, the availability of maintenance personnel andspares, maintenance policy and concepts, and other non-design factors, whereas

Ai reflects only the inherent design.

1 from ESA document Glossary of Terms

2 from MIL-HDBK-470

MDT MTBM

MTBM Ao

+

=

%100* MTTR MTBF

MTBF Ai

+

=

7/17/2019 20_RAMS_03





• Dependability3: The collective term used to describe the availability

performance and its influencing factors: reliability performance, maintain-ability performance, and maintenance support performance.

• Life Cycle: The time interval from product’s inception until its ultimate

disposal and removal from use.

• Life Cycle Costs: The summary of all costs associated with procurement of a

product, its operation and maintenance and its disposal.

• Maintainability4: The relative ease and economy of time and resources with

which an item can be retained in, or restored to, a specified condition when

maintenance is performed by personnel having specified skill levels, using

prescribed procedures and resources, at each prescribed level of maintenance

and repair. In this context, maintainability is a function of design.

• Product Support: A collective term for all operation and RAMS activities

performed for operation, maintenance and disposal.

• RAMS : Reliability, Availability, Maintainability, Safety

• Reliability: The probability that an item will perform its intended function for a

specified interval under stated conditions.

• Safety5: The freedom from those conditions that can cause death, injury

occupational illness, or damage to or loss of equipment or property, or damageto the environment.

• Scientific-Technical Project: A project established in the framework of ascientific research programme for the acquisition of the technical facilities

and/or equipment necessary for the execution of the research work.

4 Applying RAMS Technologies to Scientific-Technical Projects

4.1 Basic Considerations

The facilities, tools and equipment designed, developed and manufactured within the

framework of scientific research programmes are in most cases highly complex so called“prototypes”. These facilities, tools and equipment will built and installed only once,

without actually having the chance to benefit from the large know how and the capabilitiesavailable in high-tech and commercial serial production industries for the production of

3

from ISO 9000-4/ IEC 300-14 from MIL-HDBK-470

5 from Mil-STD-882C

7/17/2019 20_RAMS_03





complex, highly valuable, reliable products at moderate prices. Other particularities of

large-scale research facilities and equipment are the generally extremely long lifetime

expectancies and the required ability to be easily adapted to new scientific goals, programmes and needs. They very often serve as a kind of “research platform”, where the

detailed research activities are not known yet at the start of the procurement.

Prototypes are by their nature more expensive than serial products not only with respect to

their acquisition but also with respect to the operation and maintenance costs, and last not

least with respect to the costs for their ultimate disposal. If these costs are not carefully

watched and controlled from the early start of the acquisition project, the operation,

maintenance and disposal costs will sum up to an amount which is factors between ten and

hundred higher than the initial costs for buying and installing the prototypes; money which

is lost for the intended scientific research or new research activities.

One of the most effective ways to minimise the acquisition, operation, maintenance anddisposal costs, i.e. the total Life Cycle Costs, is the early and thorough consideration of the

reliability, availability, maintainability and safety performance characteristics of the

facility or equipment. These characteristics have not only a major influence on the life

cycle costs, they also determine the efficiency of the actual research work for which the

items are built.

Summary :

The technical facilities and equipment built in the framework of a scientific

research programmes have to be considered — as is done in industry — as ahighly reliable, efficient and safe production lines, or parts thereof, installed

to produce a predefined output quantity and quality of scientific data. They

have to be available for the production at each moment when needed at low

operation and maintenance costs. This means that the RAMS performance

characteristics of these production lines are of paramount importance for the

scientific research work and the achievement of the scientific results. Last

not least, beside the actual research results, also the efficiency with which

the results were obtained, reflect the thoroughness and the responsibility of

the scientists towards the economic and efficient use of the resources needed

for their work.

4.2 Phasing of RAMS Activities

“ Reliability, maintainability and safety have to be designed into the product ” is not just a

pure statement, but a fundamental philosophy in reliability, maintainability and safety

management and engineering. In order to be able to execute the work successfully, strong

support from the general management and a clear management commitment based on the

understanding of the principles of the RAMS technology, its advantages and benefits are

substantial prerequisites.

7/17/2019 20_RAMS_03





PRODUCT LIFE CYCLE

Design & Development Activities Life Cycle Phase RAMS Mgmt. and Engineering Activities

The product life-cycle phase during which the need for the product is established and (usually) its requirements arespecified

Transformation of user needs into realistic, achievable, testableRAMS characteristicsDefinition of product support requirementsAnalysis of alternative solutionsEstablishment of RAMS Programme Plans

The product life-cycle during which the product’s hardwareand/or software is created and documented as detailedmanufacturing/coding specifications, and other productdocumentation such as operation and maintenance instructionsare produced

Design analyses and compliance verifications Contractor &

subcontractor management and controlLife cycle cost analysisPreparation of product support plan including training

programmes and user documentation, support equipment, tools,spare parts, manpower, etc

The product life-cycle phase during which the product is produced, software replicated and the product assembled

Support in parts material procurementContractor & subcontractor management and controlVerification of product and .user documentationUser training during assembly, integration testProcurement of product support equipment, tools, etc

The product life-cycle phase during which the product isinstalled

RAMS performance characteristics verificationsProduct acceptance, transfer of ownershipEstablishment of product support organisation (maintenance,safety, maintenance-support)Safety certifications of integrated product

The product life-cycle phase during which the product is usedfor any purpose and is maintained and supported

Product support : Preventive, corrective maintenance,Safety activities,Analyses of modifications, updatesInitialisation of parts, materials, equipment replacement

programme

The product life-cycle phase, after the operation andmaintenance phase, during which the product is removed fromits use site and decommissioned, dismantled, destroyed or stored if necessary in protected environment.

Concept and

Definition Phase

Design & Deve-

lopment Phase

Manufacturing

Phase

Installation

Phase

Operation &

Maintenance Phase

Disposal

Phase

Safe and economic material disposalControl of hazardous materials disposal

7/17/2019 20_RAMS_03





The above flow diagram illustrates the life cycle phases definition6 as used today — with

some minor differences in the nomenclature — in nearly all modern industries and

international standards and norms. Since these definitions are of too general nature for the purposes of this document some more details will be used in the following text.

4.2.1 Organisational Aspects

For large and complex facilities and equipment it is advisable to implement RAMS Project

Management as key function in the overall project management organisation. The RAMS

Manager needs the close and intensive contact with all project management team members,

but especially with those responsible for systems engineering, quality assurance, andconfiguration management. He is with respect to the RAMS aspects the contact person for

the client/user and contractors, and he co-ordinates, monitors and controls the involvedreliability, maintainability and safety engineering departments.

4.2.2 Concept and Definition Phase

Since the Concept and Definition Phase is the most critical phase in the whole product life

cycle, it is recommended to do some further dividing of this phase into the sub-phases

“Initial Planning Phase “ and “Concept Definition Phase (Preliminary Design Phase)”

6 the definitions are take from the IEC Standard 300-2

INITIAL PLANNINGPHASE

CONCEPTDEFINITION

DESIGN &

DEVELOPMENT

PHASE

Definition of

• expected life time

• failure classification

• reliability, MTBF

• acceptable downtimes

• available resources

Definition of valid,complete, achievable

needs, operationconstraints & modes,interfaces, resources

Definition and comparisonof alternative concepts,

trade-off studies, selectionof proven final concept,final specifications

• Preliminary reliability,

maintainability and safetyanalyses of alternative

concepts

• Requirement definition &allocation for selected

concept

• RAMS Program & Plan fosubsequent phase

Project Activities Project Phase RAMS Activities

7/17/2019 20_RAMS_03





The Initial Planning Phase is the very beginning, the start of a project and the initiation of

a new product. A valid need for a product that shall help to solve an existing problem is

formulated by the scientist or group of scientists. Together with the functional performanceneeds other characteristics like interfaces, operational scenario etc. are defined. The clear

definition of the needs is fundamental for the success of the project. How can a productmeets the original needs if this needs are not carefully defined ? And if the product does

not meet the real needs, the money spent to build the product is wasted.

During this phase first thoughts have to be spent on the requirements reliability,

availability, maintainability and safety performance characteristics. Not just the functional

characteristics should be of interest, but also the operational, administrative and financial

aspects for the long operation phase. What is the affordable effort to keep the product in

operational and safe status? Already at this stage a RAMS expert must be consulted to help

to investigate and to define carefully relevant factors like

• expected total life time,

• frequency of use,

• operational modes

• acceptable number and frequency of failures (reliability, MTBF)

• acceptable system downtimes,

• available time, financial and other resources

• who will operate and maintain the product, (quantity and skill level of people)

• basic safety requirements (applicable legislation, standards, norms, etc.)

• possible location for the installation and operation of the product (access, environ-mental conditions)

An extensive sense of reality and of financial consequences is necessary in order not to killthe project already at this stage due to excessive requirements leading to an explosion of

the necessary financial budget. Also unrealistically low reliability requirements or norequirements at all concerning the maintainability and safety of the product will lead -

although not immediately at this status of the project — to a catastrophic situation at the

beginning of the operational phase if not before when it turns out that more time and

money have to be spent for keeping the system operational than for the main purpose, the

production of scientific data at a high production rate.

The subsequent requirement analysis and review work is an important interim task to

consolidate the defined needs and to prepare the first system specification.

The Concept Definition Phase -also called Preliminary Design Phase- is the period of

searching for, and establishing of alternative concepts for the product. Trade studies and

the different proposed concepts have to be analysed (preliminary analyses) with respect to

the fulfilment of the reliability, availability, maintainability and safety performance

requirements.

7/17/2019 20_RAMS_03





By comparison of the different concepts with respect to their performance capabilities,

their financial consequences on the acquisition, operation and maintenance costs, and the

realisation schedule, the most promising solution is selected for further development.

For the realisation of the selected concept the specification needs to be updated to includethe experiences gained from the comparison of the proposed concepts, and the final, agreed

and accepted performance characteristics.

The RAMS performance characteristics are specified on system and subsystem specifi-

cation level in the following typical form

a. Chapter Reliability

This chapter shall contain quantitative requirements in the form of overall reliability or

Mean Time Between Failure (MTBF) including the operational conditions andenvironmental under and the duration for which the requirements shall be meet. If applicable availability requirements may be specified like mission reliability or similar.

b. Chapter Maintainability

Because of the very close functional connection this chapter should follow immediately

after the chapter reliability. This chapter shall specify the quantitative maintenance

requirements. The requirements shall apply to maintenance in a planned maintenance

and support environment, and shall be stated in quantitative terms, like

• Mean time between maintenance actions

• Mean down times

• Man-hours per specified maintenance action

• Frequency of permissible preventive maintenance

• Maintenance complexity, e.g. number and skill level of people, variety of

maintenance equipment

c. Chapter SafetyThis chapter shall specify requirements to preclude or limit hazards to personnel and

equipment. To the extent practical, the requirements shall be imposed by citing

established legislation, and recognised standards. Limiting safety characteristics

peculiar to the item due to hazard in assembly, disassembly, test, transport, storage,operation and maintenance shall be stated. “Fail-safe” and emergency operations shall

be included where applicable. These shall include interlocks and emergency circuitsrequired either preventing injury or providing recovery of the equipment in the event of

failure.

The definition of these characteristics is a task to be performed in close co-operation with

systems engineering in order to reflect the real operational needs, and to be able to identify

those kinds of deviations of the product from its normal operating which are considered as

failure or fault situation. A failure of one measurement channel might not be considered as

a failure of the complete product, if e.g. another channel with lower accuracy can be used

instead.

7/17/2019 20_RAMS_03





In the case of different operational modes, one possible way to be able to use the product

even if one particular mode is not working anymore, is to switch to another operational

mode and/or to use the system for alternative scientific activities (operation scheduling).

When specifying the related requirements, utmost care has to be taken not to over-specifythem. The requirements should reflect realistic needs and state of the art technology. A

correct and complete specifying process includes also the definition of those methods and

procedures necessary for demonstrating in all project phases, that the product meets or is

capable to meet the specified performance requirements.

The main RAMS engineering activity during this project phase are the analysis of the

different proposed concepts and the support of the design and system engineers for finding

the optimum solution. The main task of the RAMS Project Manager is to define and plan

in close co-operation with the responsible project managers the future system andsubsystem level RAMS activities, the work procedures and processes to be applied, and therequired financial and other resources. Depending on the size and complexity of the

product, the RAMS activities will be planed in form of a separate document :

Ø Reliability and Availability Programme Plan

Ø Maintainability Programme Plan

Ø System Safety Programme Plan

or the subjects will be merged into one single System RAMS Program Plan. In relatively

small projects it might be more convenient to include the RAMS activities in the normal

project planning.

Since all the plans serve the same purpose, namely to define, manage and execute the

necessary RAMS work in the most efficient and economic way, they use similar basic

layouts and table of contents :

• Basic approach

• Organisation and responsibilities

• List of Activities

a) What has to be done ?

b) Why is the activity necessary ?c) Who is responsible ?

d) Which procedure has to be applied ? and

e) What are the expected results ?

7/17/2019 20_RAMS_03





CONCEPT AND

DEFINITION

PHASE

MANUFAC-TURING

PHASE

Summary :

At the end of the Concept and Definition Phase the reliability, availability,maintainability and safety performance characteristics valid for the entire life

time of the product are defined and accepted, based on, and in compliancewith the scientific needs and the intended scientific research activities, and

under strict considerations of the financial and other resources available and

affordable. He characteristics are complemented by a description of the

appropriate compliance demonstration methods applicable to each life cycle

phase. The detailed man-power, schedule and resources planning for an

effective execution of the RAMS tasks completes the RAMS activities of this

phase:

A sound basis for the subsequent Design and Development Phase !

4.2.3 Design and Development Phase ( Final Design Phase)

.

Design/Development Project Phase RAMS Engineering

Activities Activities

• Full scale engineeringand development,

• Verified manufactur-ing drawing sets,

•

Operation and

maintenance manuals

DESIGN AND

DEVELOPMENTPHASE

• Evolution of prelim-inary reliability/availa

bility, maintainabilityand safety analyses tofinal versions.

• RAMS compliansedemonstrations

• Planning of future

compliance

demonstrations• Parts &materials

selection

• Safety instructions for operaton andmaintenance

Fig. 4.2.2 Design and Development Phase

7/17/2019 20_RAMS_03





The Design and Development Phase is defined by the IEC Standard 300-2 as :

“That product life-cycle phase during which the product’s hardware and/or software is created and documented as detailed manufacturing/coding

specifications, and other product documentation such as use andmaintenance instructions produced.“

This is the full-scale engineering and development phase for the product that has been

selected and specified at the end of the previous phase. The engineering and development

activities are nearly in parallel analysed and supported by the RAMS engineering process:

• Break down of system level requirements to and lower level requirements

• Tailoring of verification methods to subsystems, unit, assemblies, etc

• Performance of reliability, availability, maintainability and safety analyses to

evaluate the design with respect to its capability to meet the specified RAMS performance characteristics as soon as the first design drawings, concepts etc. are

available

• Collection and combining of lower level analyses results to system level reliability,

maintainability and safety analyses.

• Feedback to and support to the design and development engineers for necessary

design changes and improvements.

• Generation of RAMS documentation for the Operation and Maintenance Phase

• Review of operation and maintenance manuals,

• Initiation of the legal safety compliance process

Some basic tools generally used in RAMS engineering are

A. General RAMS Engineering

Functional Analysis

Life Cycle Cost Analysis

B. Reliability Engineering

Reliability Apportionment/Allocation

Reliability Modelling and Prediction

Reliability AnalysisFailure Mode and Effects and (Criticality Analysis), FME(C)A

Fault Tree Analysis, FTA

C. Maintainability EngineeringMaintainability Allocation

Maintainability Prediction

Maintainability Assessments/Analysis

Maintainability Tests

7/17/2019 20_RAMS_03





D. Safety EngineeringPreliminary Hazard List

Preliminary Hazard AnalysisSubsystem Hazard Analysis

System Hazard AnalysisSafety Compliance Assessment

Operating and Support Hazard Analysis

Workplace Safety Analysis

Software Hazard Analysis

Some of the above analyses and lists may serve only for the specific purpose they are

performed for, like a workplace safety analysis or maintainability analysis. A large fraction

of the results of the analysing work are however of interest to all RAMS disciplines.Typical analyses of this type are the reliability analyses, the functional analyses or theFMEAs and FTAs.

Monitoring and control of contractors’ and subcontractors’ reliability, maintainability and

safety activities is an important activity of the RAMS Project Manager. The RAMS

programme plans prepared during the Concept and Definition Phase form the basis for

RAMS related internal work as well as for the work of the contractors and subcontractors.

Depending on the type, criticality, complexity, and the technical and financial amount of

the work contracted, and the contractors experiences, separate reliability, maintainability,

and safety related programme plans tailored to the particular subject of the contracted work

have to be prepared by the contractor. These plans should carefully be reviewed by theclients RAMS Project Manager for compliance with the overall RAMS approach. Also the

results obtained by the contractors during this period should be reviewed to identify any

deviations from the specification and to be able to launch corrective actions on time.

Summary :

The design and development activities and the RAMS engineering are

iterative processes ending with the manufacturing documentation of a

product. If the RAMS programme plans are strictly applied, the functional performance characteristics of the product and its and agreed life cycle

costs are also during this project phase perfectly under control. Even if it

turns out, that a certain requirement cannot be fulfilled due to technical

problems, financial or schedule constraints, or a combination of these

factors, and the respective requirement has to be changed, the impacts of

the change on the functionality, the operation and maintenance, and the

total life cycle costs are immediately analysed. The results serve a basis for

the project management’s decision finding process.

7/17/2019 20_RAMS_03





4.2.4 Manufacturing Phase

The Manufacturing phase is from the RAMS point of view again a critical phase. While in

the previous phase theoretical analyses where the main tool to verify the compliance with

the specified requirements, this theoretical work is now confirmed -or not- by actual failure

rates values of the ordered components and materials and/or practical experiences from

inspections and tests.

Changes of the design might be the only possible consequence if it turns out, that the

RAMS performance characteristics of the ordered parts, materials or equipment differ in an

unacceptable amount from the specified behaviour.

Note: AIT = Assembly, Integration and Test

Manufacturing Project Phase RAMS Engineering


DESIGN AND

DEVELOPMENT

PHASE

LOWER LEVEL

MANUFACTURING

& INSPECTIONS

SUBSYSTEMLEVEL

AIT

SYSTEM

LEVEL

AIT

• Parts & MaterialsProcurement

• Manufacturing

• Off the shelf equip-ment Procurement

• Assembly,

• Integration

• Test

• User Training

•

Acceptance Tests

• Assembly,

• Integration

• Test

• User Training

• Acceptance tests

• Input to ProcurementSpecifications

• Incoming Inspections

• Definition of in-manufacturing tests

• Burn In

• Maintainabilityverifications

• Maintenance training,

• Safety verifications

•

Safety training

• Reliability monitoring programme

• Maintainabilityverifications

• Maintenance training

• Safety verifications

• Safety training

Fig. 4.2.4 Manufacturing Phase

7/17/2019 20_RAMS_03





There are four fundamental principles for a successful manufacturing of highly reliable

systems and components :

• Use standard parts and materials with known reliability wherever possible

• Order parts materials and equipment only from well known reliable sources

• Use stable and reliable manufacturing methods and procedures whenever possible

• Use experienced people to perform the work

These principles do not only reduce the risks due to new parts and materials without any

traceable history. They also increase the confidence in the results of the reliability,

maintainability and safety analyses, and they minimise the in-manufacturing and end-item

inspection and control effort.

“Reliability tests “ of parts and components or even integrated units or subsystems should

normally not be considered in a scientific–technical project as verification method and

reliability compliance demonstration. They are too expensive and there should actually not be a need for this kind of tests if the above fundamental principles are carefully considered.

A realistic and practical way to bring the end product into a failure rate stable condition

right from the start of the operation is the execution of Environmental Stress Screening.

“ Environmental stress screening is a test or a series of tests specially designed to disclose

weak parts and workmanship defects for correction. It should be applied to parts,

components, ... or equipment ... to remove defects which would otherwise cause failureduring higher level testing or early field service.”7

The assembly, integration and test periods on subsystem and system levels are the ideal

opportunities to perform operator and user training programmes. Using the operation,

maintenance and safety plans and manuals prepared during the Design and Development

Phase the operation and maintenance staff becomes familiar with the operation and

maintenance activities and with the relevant safety precautions and procedures.

Proper testing at the end of the manufacturing process is an effective means to eliminate

material and workmanship defects before shipping the equipment to the installation site.

However,

testing does not improve reliability or safety. Only correctiveactions that prevent the reoccurrence of the failures actually

improve the reliability and safety characteristics !

7 from MIL-STD-785

7/17/2019 20_RAMS_03





Summary :

Starting with the Manufacturing Phase the RAMS activities change fromtheoretical, analytical, and specifying work to practical, verifying,

reassurance work. From now on detected non-compliance’s result — if notaccepted- in expensive and time consuming hardware and/or computer

software changes. Therefore the results obtained from the RAMS activities

of the previous phases have to be sound, realistic and without ambiguities.

Excellent co-operation and information flow with all participants including

the contractors and subcontractors are essential.

A perfectly functioning “Failure Reporting and Corrective Action System“

combined with a well functioning “Configuration Control System” and a

well organised Quality Assurance System are a fundamental prerequisiteto avoid undetected and not acceptable alterations of the reliability,availability, maintainability or safety characteristics, and to keep also

during this phase the functional performance characteristics and thereby

the life cycle costs under control.

4.2.5 Installation Phase

During this project phase the product is installed at its operation site, tested and handed

over to the client and the clients’ operation and maintenance staff.

Installation Project Phase RAMS Engineering


PRODUCT

INSTALLATION

& TEST

• Installation

• Tests• Preparation for opera-

tion and maintenance

• Operation, mainte-

nance, safety training

MANUFACTURING

PHASE

PRODUCT ACCEPTANCEAND TRANSFER OF

OWNERSHIP

• Final compliance verifi-

cations :

-Reliability/Availability-Maintainability

-safety

• System safety compli-ance certification

• Safety training

Fig.4.2.5 Installation Phase

7/17/2019 20_RAMS_03





No intensive reliability engineering work is related to this phase, except the review of non-

compliance reports, change requests, etc.

From the maintenance and the associated logistic support point of view this phase is quite

important. It includes the preparational work for the subsequent operation and maintenance phase, like storing of spare parts and maintenance support equipment, setting up of the

maintenance organisation and crew, implementation of work schedules, safety plans and

procedures, etc.

Summary:

The acceptance of the product by the client and the handing over of the

product are legally important acts. Not only that the client becomes theowner of the product, the client is from this moment on totally responsiblefor the correct and safe operation and maintenance of the product in

accordance with the plans, instructions and manuals delivered by the

supplier as part of the product.

For non-serial systems and products of “prototype characteristic”, like

large complex facilities for scientific research, the deliverable

documentation must include a status list (Configuration Item Data List)

showing the actual configuration status of the product at the moment of the

acceptance by the client. Any modification of this status by the client/user

after the acceptance without formal agreement by the supplier may free thesupplier from his liability for the product.

7/17/2019 20_RAMS_03





4.2.6 Operation and Maintenance Phase

Although the best efforts have been spent to design and manufacture a reliable, highly

available, maintainable and safe product, some problems may not evidence themselves

until the product will be used in the real environment and is operated by the foreseen users.

Functional problems will occur, and it is important to determine their criticality and

whether the problems are serious enough to require corrections. If the problem is still

covered under the warranty, the supplier must take the necessary actions.

If the problem is due to misuse of the product or lies in the client’s maintenance policy

and procedures, these factors have to be changed.

OPERATION &

MAINTENANCE

PRODUCT ACCEPTANCE

AND TRANSFER OF

OWNERSHIP

• Operation for scienticicresearch includingalredy initially foreseen

adaptations

• Standard preventive and

corrective maintenance

Operation and Maintenance Project Phase RAMS Engineering


• Monitoring of RAMSevolution of characte-

ristics

• Improvements wherenecessary

• corrective maintenence

UPDATINGS&

MODIFICATIONS

• Selection of adequate

equipment for replace-ments

Assesment of proposed

modifi• ations with respect to

• Updates due to wear outand new techno-logies

• modifications due tomalfunction, improve-ments,ornew research projects

DISPOSAL

Fig. 4.2.6 Operation and Maintenance Phase

7/17/2019 20_RAMS_03





The generally very long lifetime of large and complex research facilities leads automati-

cally to necessary updates of equipment because the old equipment is outdated, a new

equipment with increased performance characteristics will drastically reduce the researchefforts, and similar. Computers and their increasing speed and memory capacities are a

typical example. But not all equipment which is on the market and promise to do miraclesis adequate for fulfilling the availability demands and/or other RAMS characteristics. In

this context reference is made to one of the four fundamental principles mentioned in

chapter 4.2.4 Manufacturing. “use only parts and materials with known, verified reliability

characteristics.

Even if spare parts are provided for equipment which was specially designed and

manufactured for the product, replacement problems will occur in 5, 10. 15 years. The

originally used technologies are not available anymore, the original supplier does not exist

anymore, etc.. This means, that in order to guarantee the specified availability of the product for the entire life time, modification programmes have to be initiated relativelyearly in the operation and maintenance phase. Their starting date depends on one hand on

the critical life time of the equipment but on the other hand also on the general evolution of

the technologies used in the original equipment.

Summary :

Modifications, modernisation, updates, and equipment replacements, as

well as adaptations to changing research goals have to be considered from

the beginning of a project although these aspects may only become

relevant in 5 years or later. In a period of 5 years two or three generationsof new computers and associated parts and materials will be on the market.

To find spare components for the “old“ equipment will not be trivial. A

close monitoring of the failure occurrence frequencies, and the

implementation of special update programmes to be able to start

procurement activities well in advance of increasing failure rates are

mandatory parts of the overall maintenance planning.

Since product modifications and updates will occur during the long life

time Configuration Management and Control must be performed by owner

to keep the product safety and consequently the safety of the user andmaintenance personnel in a controlled status. It goes without saying that all

modifications need to be analysed and approved by RAMS experts.

Provisions have to be taken in advance to make sure, that not only a

general RAMS expert is available, but an expert familiar with the product,

the specific product (logistic) support, and the constraints generated by the

scientific programmes and the environment of scientific institutes.

7/17/2019 20_RAMS_03




L it d f 15 D 85617 A li T l +49 8092 7082 77 F +49 8092 7082 85 @t li d

4.3 Disposal Phase

The disposal or phaseout of a product or parts of it has to be considered as sub-phase of the

product’s life cycle from the beginning of the project.

In connection with the expiry of the product’s useful life, wear-out or if the product

becomes obsolete, the owner will be faced with the critical question what to do with the

material :

Ø Dismantling of the product or parts thereof

Ø Recovery of precious metals or other valuable, recyclable materials

Ø Salvage of equipment and components for use in other products

Ø Safe disposal of hazardous materials

Ø Logistics support of disposal

The most elegant and advanced solution is to answer these questions already during the

Concept and Definition Phase and to include corresponding requirements in the product

specification. Thereby everybody involved in the procurement is forced to take the

disposal already into account during the design and development phase, and to generate

safe, efficient and economic methods and procedures for activities which will be

performed in the far future.

Download - 20_RAMS_03

Top Related