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Reliability and
Maintainability Engineering Program Approach
The approach to a reliability and
maintainability program is dependent upon many factors that
include the customer's requirements, the business strategy
of the company, and the size of the project etc. The
effective implementation of an R&M Engineering Program
must take into consideration these and other factors.
Detailed in Mil-Std-785 and Mil-Std-470 are various tasks
associated to the reliability and maintainability
engineering program. Careful task selection must be made for
each particular program, to ensure that the reliability and
maintainability requirements and objects are achieved. How
do you determine the reliability of a system, taking into
consideration the mission operation profiles? How do you
optimize the reliability (and availability) of a system
with respect to the life cycle cost? Where should you focus
your engineering efforts to minimize program cost? These are
just a few of many questions that need to be asked and
answered prior to implementing a reliability and/ or
maintainability program.
Reliability and
Maintainability Program Requirements
Program requirements can be derived
from the customer or the company's business
strategy.
For
example:
Customers
requirements:
The customer may request
specific R&M engineering tasks to be implemented.
This may include the development of reliability and
maintainability models, or reliability and
maintainability testing, to collected field data.
Availability analysis could also be a requirement.
From the view point of a
customer, R&M performance characteristics may be
critical in terms of the impact upon a system
availability, safety and cost. In one scenario the end
user of a military product requires a certain amount of
confidence that a product will perform its operational
function when required to do so and for a set duration.
In another scenario a commercial enterprise who releases
a product to market with an inadaquate reliability,
whether it is a television or an automobile, would be
severely penalized with warranty costs. It is also true
that any expected unreliability issues can be off-set by
augmenting the warranty charge in a product. This only
serves to dull the competitive edge of the manufactures
product. This is also true for the maintainability
characteristics of a product. Inadequacies here could
result in excessive downtime, affecting the overall
availability and/ or repairs cost to a consumer,
impacting directly the product and the company's
reputation.
Company Strategy:
The main concern to a
company could be to adopt a strategy to develop a
reliable and maintainable product. A key business
objective must be to provide a product, which is highly
reliable and maintainable, as these two characteristics
have a direct impact on a product's operational and
maintenance cost to the end user. This is commonly
referred to Life Cycle Cost of Ownership, and can be of
great importance to the company, in the event it invests
in a single product or multiple products for more than
one customer. This may include relatively simple
standalone products such as a television, to more complex
electronic and mechanical systems, such as a ground based
early warning radar system.
It should also be realised that
these days, many government and commercial organisations,
when requesting bids are asking for LCC data elements to
be provided with a proposal submission. The LCC data
elements consist of key costs drivers, such as the
reliability and maintainability performance
characteristics. It is quite obvious from this, that
these organisations are not just placing the selection
criteria emphasis on functional performance, but also on
R&M and LCC attributes and characteristics. If
reliability and maintainability are not considered and
integrated into in the product design, it is highly
unlikely that the product will stand out from the
competition.
Reliability and
Maintainability Program Plan
For more complex R&M programs,
the need to develop a R&M program plan presents itself
as a must. The R&M program plan will identify as a
minimum the following
Program requirements:
Specify what the program R&M requirements are, in
terms of quantitative and qualitative objectives and also
the required R&M engineering activities;
Program scope and
objectives:
Define the limitation of
the program in terms of scope, detailing the main
objectives;
Program Management:
Detail the general program management effort, in
terms of Work Breakdown Structure (WBS) and program
schedule, showing relationships through organization
charts to other key program players and with the customer
etc.;
Program Tasks: Detail the
actual R&M program tasks that will be implemented,
making reference to the specific requirements and
specifications;
Interface with design
engineering and other
groups:
Identify the interface
particularly where critical inputs are required. These
inputs could be in the form of program milestones and
engineering support data;
Interface with the customer
or end user: This interface can be captured by
working group reviews, telephone hot lines and status
reports;
Interface with
Subcontractors: Depending on the involvement and
level of effort required from a subcontractor, key
information required may be the Point-of-Contact, their
deliverables and the schedule tied to their deliverables;
and
Delivery
schedules:
List the deliverables
that are required this maybe the results or reliability
and maintainability analyses and testing
results.
Reliability and
Maintainability Program Tasks
The R&M program tasks can be
broken out into the following categories;
Program
Control:
Has to take into
consideration what is required to be done, when is it
required to be done and who shall implement the required
tasks.
What is required; Will
depend upon what the customer's requirements are and/ or
what the company strategy is. Again, it has to be take
into consideration the type and size of the project. Is
it a developmental, commercial or a hybrid design
solution? Is it a simple product or a more complex
system? This leads to several activities that may be
implemented:
Program
reviews:
These would include
Design Kick-off Meetings, Design Reviews, working groups
and Test Readiness Reviews.
Customer
Liaisons:
These can be conducted
as part of a formal program review or in some cases in
adhoc fashion as required.
Subcontractor
Controls:
Depending upon the type
of program and the level of support required from a
sub-contractor, will dictate the hows, whats and whens of
their involvement. They themselves could be required to
implement a R&M program and be required to undertake
the same program tasks, or in the case of less
complicated projects/ programs they could be required to
perform some basic analytical tasks and/or provide basic
engineering data.
Engineering
Interface:
The R&M program
generally has to be coordinated and synchronized with
other engineering efforts.
Design Impact and Evaluation:
To ensure that R&M is an inherent design
characteristic, the greatest influence is achieved as
early as possible in the concept and design phase. This
can be implemented and monitored through the
implementation of key R&M analyses.
Design Criteria: This is
one of the more import aspects of the design process.
Based upon the product requirements, careful
consideration must be given to the approach of defining
the R&M design criteria, to ensure that the
required R&M characteristics are achieved.
Trade-off
analyses:
This effort is
particularly important where certain elements in the
equipment/ system architecture consist of COTS or NDI
elements and/ or components. These analyses can be both
quantitative and qualitative. The output of these
analyses will provide an understanding if one
configuration solution compared to another is more
reliable and/ or maintainable.
R&M Modeling: This
effort will identify potential reliability and
maintainability performance characteristics of the
equipment/ system design. The modeling can be simplistic
in nature, or more complicated depending on the
configuration of the system with respect to redundant
elements.
Failure Modes and Effects
Analyses:
This is a widely used
analysis and if completed correctly can provide very
useful feedback to the designers and other engineering
activities, such as safety and logistics
engineering.
Design
Verification:
The design verification
of the R&M characteristics can be achieved in
several ways. One would be to validate it by the analyses
performed during the design process. An issue associated
with the analyses, which must be overcome, are the
assumptions made, or conclusions based upon engineering
judgement. Thus a validation effort may be extended and
implemented to gather actual performance data. The real
R&M performance of an equipment/ system will be
revealed once it is deployed and operating in its
intended environment. This could be too late for some
programs, as a validation effort maybe required prior to
a full-scale production. An approach could be implemented
through reliability and maintainability testing. These
tests can include a combination of reliability and
maintainability demonstration (or qualification),
environmental stress screening and/ or reliability growth
tests.
Reliability and
Maintainability Interaction with other
organizations
The importance for the interaction
between reliability and maintainability engineering and that
of other related engineering disciplines cannot be over
emphasized. The more prominent engineering disciplines are:
- Program Management and
Engineering
- Logistics Support
Engineering
- Safety
Engineering
- Testability
Engineering
- Configuration
Management
- Quality
Assurance
Program Management and
Engineering
Program Management and Engineering
are key to a successful reliability program. Generally it is
the program manager that will rely on the reliability
engineering effort. The program manager will normally be
aware of the value and importance of a well planned and
executed reliability and maintainability program, in
particular when there are liquidated damages associated with
a contract. Otherwise some program managers can display an
attitude that the whole reliability and maintainability
effort may be a nice luxury which cannot be afforded nor
required.
Logistics Support
Engineering
Reliability Engineering Analysis
and tasks are instrumental in supporting the Logistics
Supporting Engineering functions. These include reliability
analyses such as the Failure
Modes and Effect Analysis
and Reliability
Predictions. Additional
tasks that may be of importance to the Logistics Support
Engineering is the Failure Reporting and Corrective Action
System (process), commonly know as FRACAS.
Safety
Engineering
Reliability Engineering Analysis
and tasks are instrumental in supporting the Safety
Engineering functions. These, like Logistics Engineering
includes reliability analysis such as the Failure Modes and
Effect Criticality Analysis (FMECA) and Reliability
Predictions. The output of these analyses may serve as
inputs to the safety analysis, such as the FMECA may
identify failure modes which would be shown as basic events
in a Fault Tree Analysis (FTA)
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