Applied
R&M Manual for Defence Systems
(GR-77 Issue 2011)
Part
C - R&M Related Techniques
The activities
above are achieved by applying R&M techniques. There are many techniques that have been
developed over the years. This section aims
to present a fairly comprehensive set of techniques but can
not guarantee to cover all techniques.
Chapter
1 Operational Needs Analysis
In terms of
R&M, Operational Needs Analysis addresses the effect of various levels of
R&M on the delivery of functionality.
The levels of R&M considered will be influenced by the practicality
and cost of their achievement. It
therefore contributes to the determination the appropriate R&M requirements
to be specified.
Chapter
2 Environmental Conditions Analysis
The environmental
conditions are not really within the remit of the R&M function. However they do affect the R&M
performance and this aspect is usefully included in this manual. Additionally, leaflets 1, 2 & 3 within
this chapter address specific areas, namely; Leaflet 1 – The Impact of
Environmental and Terrain on Reliability, Leaflet 2 – Impact of Environmental
and Terrain on Equipment Reliability – Land, and Leaflet 3 – Environmental
Failure Modes within the Maritime Domain.
Chapter 3 Modification Impact Analysis
Any modification
carried out on a system will impact upon other system performance parameters in
addition to those that are key to the purpose of the modification. The R&M performance is very likely to be
altered by every modification. Impact
analysis aims to determine the extent of this alteration at a stage when this
can be considered in the decision on proceeding with the modification. (This
chapter is presently being developed)
During the
specification and design stages, a number of solutions are likely to be under
consideration. A number of factors
should be considered in deciding between solutions. One of these is R&M. This chapter concentrates on the R&M
aspects of trade-off studies.
Chapter
5 R&M Allocation and
Apportionment
Once R&M
requirements have been set against high level functions or equipment assemblies
it is necessary, as part of the design process, to identify the allowable
contributions from the lower level items of equipment. This is particularly so when these items are
being produced under separate or sub- contracts.
Chapter 6 High Integrity Specification (of all
types of system and equipment)
The design of
equipment (particularly software) with a reliability requirement beyond that
which is practically testable during the pre-delivery and early service stages
of a systems life has been addressed in recent years. Although the solutions currently available
can not be seen as perfect, best practice should be followed. This applies to both the specification area,
where appropriate wording is required, and the design, where appropriate
techniques must be used in order to make the necessary claims in the acceptance
phase. (This chapter is presently being developed)
Part derating is a
long established reliability technique although perhaps now with different
justification to that applied in the past.
Recent research has shown that the relation of reliability and
temperature is not as defined by the Arrhenius equation. However derating is still valuable in
ensuring that elements of the system are operated within their specification
even when subjected to external events beyond the limits defined in the
specification.
The designation of
certain items as ‘lifed’ remains a valuable tool in controlling mechanisms of
failure. Its use is not popular from a
logistical viewpoint, particularly when built in test can detect failure of the
lifed item. This section explains their
operation and discusses their use.
Critical items
lists are another valuable tool that are often misused. This section explains
their operation and discusses their use.
Chapter 10 High Integrity Design
The best point to
introduce high reliability is in the specification and design phases (a right
first time approach). This is
particularly so in the software area where Def-Stan 00-55 requires specific
activities to be performed during design.
This chapter addresses the usage of detailed techniques and references
appropriate literature. (This chapter is presently being developed)
Chapter 11 Redundancy Optimisation
The use of
redundancy needs to be well thought out.
This chapter addresses the need, benefits and pitfalls. (This chapter is
presently being developed)
Chapter
12 R&M Design Criteria
On a large project
it is useful to define criteria for the design process to follow. This chapter addresses the setting,
monitoring and dealing with deviations from such criteria.
Chapter
13 Test, Analyse and Fix
Test, analyse and fix
is a practical approach to identifying and resolving the weak areas of a
design. This chapter discusses the
application of the technique.
Chapter
14 Step Stress Testing
This chapter
discusses the application of the step stress technique and comments on its
advantages, applicability to situations and the constraints.
Chapter
15 Reliability Growth Testing
This chapter
addresses the technique of reliability growth testing, its application, its
advantages and problems that may be encountered.
Chapter
16 Highly Accelerated Stress Testing
The benefits and
short comings of highly accelerated stress testing, together with the process
are addressed in this chapter.
Chapter
17 Ease of Maintenance Assessment
Ease
of Maintenance Assessment (EMA) is the means whereby the Project Team confirms
whether equipment can be maintained in-service and meets the maintainability
and ease of maintenance criteria within the maintenance strategy. This chapter provide guidance for the
production and publication of EMA Reports.
Chapter
18 Data Reporting, Analysis and
Corrective Action System
This chapter
addresses the DRACAS process, the collection flow and storage of relevant data,
its analysis and closing the loop to achieve improvements.
Chapter
19 Sneak Circuit Analysis
Sneak circuits are
circuits (normally electronic although the principle applies to electrical,
pneumatic and hydraulic) outside the main functional path that might affect the
function. An example includes the
passage of a signal through monitor connections, power supply lines and the
capacitative coupling of an amplifier’s input and output causing oscillation. This chapter discusses the aims, application
and benefits of such analysis.
Chapter 20 Tolerance Analysis
Any design is
implemented using components with actual values slightly different from the
ideal. Statistical consideration of the
effect of these inaccuracies on the accuracy of the output is of benefit to the
design review process and can lead to changes that reduce production cost and
increase reliability. The chapter
addresses the process, aims and benefits. (This chapter is presently being developed)
Chapter 21 Built-In-Test Effectiveness Analysis
The effectiveness
of built in test is important to availability in that the built in test
initiates corrective maintenance. This
chapter addresses the appropriate examination of the system and the application
and extension of the FMECA technique to elicit the relevant results. (This
chapter is presently being developed)
Chapter 22 Testability Analysis
Poor testability
increases the probability of equipment going into service with latent
faults. This can reduce the exhibited
reliability from that exhibited during design testing. This chapter discusses the ways of performing
such analysis and the benefits thereof. (This chapter is presently being
developed)
R&M checklists
provide a rapid check of important aspects of a design. This chapter addresses their content,
tailoring them to a particular review and the benefits obtainable.
Chapter 24 Physics of Failure
The physics of failure
technique aims at identifying the optimum location in a design to apply
resource in order to improve reliability.
This chapter discusses the process, the benefits and the use of the
results. (This chapter is presently being developed)
Chapter 25 Worst Case Stress Analysis
All prediction work
becomes invalid if any part of the system (however small and seemingly
insignificant) is used outside its operating envelope. Worst Case Stress Analysis looks for such
‘weak links’ in the system. The chapter
addresses the application and benefits of the technique. (This chapter is
presently being developed)
Chapter
26 Goal Structuring Notation
Goal Structuring
Notation (GSN) is a graphical notation for presenting the structure of engineering
arguments. The approach may be used to
present any situation where one wishes to make a claim and where the support
for that claim will be based upon evidence and argument. This would include situations such as
R&M, safety, support or legal based cases.
Chapter 27 Fault Tolerance Analysis
This chapter
discusses the application, benefits and use of the results of Fault Tolerance
Analysis. (This chapter is presently being developed)
Chapter
28 Dependent Failure Analysis
This chapter
discusses the application, benefits and use of the results of Dependent Failure
Analysis.
Chapter
29 Fault / Success Tree Analysis
This chapter
discusses the application of Fault Tree Analysis and the modifications to
perform Success Tree Analysis.
Chapter
30 Reliability Block Diagrams
This chapter
discusses the application of the RBD technique.
Chapter
31 Human Impact on R&M
Human impact on
R&M is a separate technique to Human Reliability Assessment but a major
support to it. The chapter addresses the
application and use of the technique.
Chapter 32 Human Reliability Assessment
Human reliability
is an area of growing concern. The
chapter looks at the technique for assessing human reliability and using the
results to achieve positive improvement. (This chapter is presently being
developed)
Chapter
33 Failure Mode, Effects (and
Criticality) Analysis (FMEA/FMECA)
FMECA is a well
known technique but needs explaining with emphasis on the purpose, tailoring of
worksheets and use of the results.
Chapter 34 Event Tree Analysis
ETA is a well
established technique. The chapter
explains its use and how to link it to FTA for an overall cause-consequence
view. (This chapter is presently being developed)
Chapter 35 Availability Prediction
Availability is
predicted by combining reliability and maintainability. This chapter concentrates on ensuring that all
the correct elements are combined and the methods of combination. (This chapter
is presently being developed)
Chapter
36 Reliability Prediction
Reliability
Prediction has been the subject of much discussion in recent years. This chapter will attempt to present a
balanced view of the arguments such that the reader can decide on the
applicability for a given application.
The chapter will also emphasize appropriate use of the results and
address the misunderstandings held by many engineers and engineering managers.
Chapter 37 Maintainability Prediction
Maintainability
Prediction has not been discussed as vociferously as Reliability Prediction
mainly due to its lower prominence.
However a similar approach is appropriate with an emphasis on the
understanding of the meaning and usefulness of the results. (This chapter is
presently being developed)
Markov Modelling is
a useful technique for the analysis of more difficult situations and the
determination of generic results (such as those in Part D Chapter 6). This chapter presents the method.
Chapter
39 Availability Demonstration
Demonstration,
here, is the practical determination of the truth of a hypothesis. In this case that the availability is greater
than a certain value with a given level of confidence. This chapter addresses the way of designing
and carrying out such a demonstration
Chapter
40 Reliability Demonstration
As for availability
but substituting reliability.
Chapter
41 Maintainability Demonstration
As
for availability but substituting maintainability.
Chapter 42 Testability Demonstration
As
for availability but substituting testability.
(This chapter is presently being developed)
Chapter
43 Assurance Through
the R&M Case
This chapter
presents an overview of the R&M Case with reference to the Def-Stan and ways of satisfying the requirements.
Chapter
44 Production Reliability Acceptance
Testing
This chapter
discusses the techniques applicable to testing the reliability through the
production run.
Chapter
45 Environmental Stress Screening
This chapter
addresses the benefits of ESS and the ways of generating and carrying out an
effective programme.
Chapter
46 Data Classification
This chapter
provides background and discussion on the implementation of the Defence
Standard.
Chapter
47 In-Service Data Collection
The uses and
benefits of collection are stressed in this chapter while addressing the
available methods. CuSum
is one technique addressed under this chapter.
Chapter
48 Monitor/Control of
Subcontractors/Suppliers
In most systems the
prime contractor contracts out much of the work to sub-contractors. The extent to which the main contract
requirements for R&M should be passed through and the extent to which an
allocation process should be carried out is addressed for different situations
in this chapter.
Chapter
49 R&M Plans & Programmes
R&M Plans &
Programmes are an important element of managing for the achievement of R&M.
This chapter looks at the similarities
and differences of R&M Plans to other project plans and why (or if) a
separate plan is needed. The provision
of R&M procedures within an organization is also discussed.
Chapter 50 R&M Data Storage
Data storage is central
to the long term improvement of R&M for specific systems and systems in
general. This chapter looks at the types
of data to be stored, the degree of detail required and the period of time for
which data remains valid. (This chapter is presently being developed)
Chapter
51 Software Reliability Techniques
This chapter
contains guidance on the two complementary approaches to the achievement of
software reliability at the design and implementation phase; Fault Avoidance
and Fault Tolerance. Fault avoidance
requires taking steps to avoid faults during software development, and to
detect and correct those faults that do occur. Fault tolerance requires
designing software to correct or tolerate errors in service.
Chapter
52 Software Reliability Evaluation
This chapter
describes the methods that can be adopted to evaluate the software reliability
that has actually been achieved, including evidence from testing, field data, fault
data and analytical arguments.
Chapter 53 Fishbone
Analysis
Fishbone analysis
is a form of cause and effect analysis and is used to explore the causes of a singe effect. The
fishbone diagram enables the relationships and hierarchy of events to be arranged
and depicted in a logical order proving a means for their relative importance
to be conveniently compared. (This
chapter is presently being developed)
Chapter 54 BIT
Effectiveness Analysis
BIT effectiveness
analysis is a form of testability analysis that embraces the relative virtue
and outcomes (effects) of two or more courses of action. Bit effectiveness analysis is commonly used
in the fields of electronic and system engineering where it may be inappropriate
or impractical to practically determine the effectiveness of BIT under all
system conditions particularly when that system is a subset of a much larger
host system or whose interfaces and/or functionality may change subject to
application. (This chapter is presently being developed)
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