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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 inadequate
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 offset 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 realized 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 Kickoff 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 subcontractor, 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.
Tradeoff 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 judgment. 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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