Availability and Maintainability in Engineering
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SENG 5232
ENGINEERING SPECIALTY INTEGRATION
AVAILABILITY
MAINTAINABILITY
RAM CASE STUDY
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Last Week:
Brief Recap
•
Availability
•
Maintainability
•
RAM Case Study
Today…
What is Availability?
Measure of the degree to which an item is in an
operable state and can be committed at the
start of a mission when the mission is called for
at an unknown (random) point in time.
What is Availability?
Simple Translation:
The probability that the
system is operation or available at time t.
A function of:
1.
How often failures occur and corrective maintenance
is required
2.
How often preventative maintenance is performed
3.
How quickly indicated failures can be isolated and
repaired
4.
How quickly preventative maintenance tasks can be
performed
5.
How long logistics support delays contribute to down
time.
What is Availability?
Availability
Requires a description of how the item/system is to
be used.
How item will be operated
Maintenance policy
Maintenance concept
Adequacy and responsiveness of the supply system
Affected by how often a system becomes unusable
and how long it takes to restore
Availability Metrics
Elements that determine availability
Failures
Inherent level of reliability built into the system
Maintenance
Corrective and preventative
Length of time required
Resources
Maintenance personnel available
Skill and K of personnel
# and availability of spare/repair parts, support
equipment, etc.
Availability
Three types of availability
Inherent Availability
Achieved Availability
Operational Availability
Inherent Availability
Probability the system (when used properly) will
operate satisfactorily for a period of time
without
maintenance
Does not include preventative or scheduled
maintenance
AI = MTBF(MTBF + MTTR) – 1
MTBF: Mean Time Between Failure
MTTR: Mean Time To Repair
Achieved Availability
Probability the system (when used properly) will
operate satisfactorily for a period of time
Preventative or scheduled maintenance is included
AA = MTBM(MTBM + MAMT) – 1
MTBM – mean time between maintenance
MAMT – mean active maintenance time
Operational Availability
Probability the system (when used properly) will
operate satisfactorily for a period of time
when it is
called upon
Preventative or scheduled maintenance is included
AO = MTBM(MTBM + MMDT) – 1
MTBM – mean time between maintenance
MMDT – mean maintenance down time
Inherent vs. Operational Availability
Availability, Simplified
Availability is measured in terms of uptime and downtime.
Operational availability:
Downtime
Waiting for spare parts to arrive via supply chain (logistics
downtime)
Time to repair (maintenance time, queue for maintenance)
Time during which system was
capable of performing all
required functions in a given
interval
Time during which system was
supposed
to be up during a
given interval
(Uptime + Downtime)
Module 5 Exercise 5
Can a product with identical failures (rates and events) have
different perceived or measured availability for different
customers?
Question:
What is Maintainability?
The probability that an equipment will be retained
in, or restored to, a specified condition in a given
period of time, when maintenance is performed in
accordance with prescribed procedures and
resources.
What is Maintainability?
The
probability
that an equipment will be retained in, or restored to,
a specified condition in a given period of time, when maintenance is
performed in accordance with prescribed procedures and resources.
What is Maintainability?
Probability: Proportion (or %
of the time) that a
maintenance task is performed in a specified time.
This probability will
depend on?
Probability
The way equipment is designed
The tools available
The skill of the person doing the repair
The environment
Technical manuals
Ease of doing trouble shooting
Getting access to the critical area
Motivation of the person doing the repair
The probability that an equipment will be
retained
in, or restored to
, a specified condition in a given
period of time, when maintenance is performed in
accordance with prescribed procedures and
resources.
What is Maintainability?
Retained
in, or restored to: Preventative or
corrective maintenance. With either, the
equipment is brought back to original condition.
The probability that an equipment will be retained
in, or restored to, a
specified condition
in a given
period of time, when maintenance is performed in
accordance with prescribed procedures and
resources.
What is Maintainability?
Condition:
Original design level.
Some degradation
of system is expected, e.g.
car.
The probability that an equipment will be retained
in, or restored to, a specified condition in a given
period of
time
, when maintenance is performed in
accordance with prescribed procedures and
resources.
What is Maintainability?
Time:
Time it takes to perform the maintenance.
Is a function of equipment design.
Time
When equipment is designed, length of time
maintenance is going to take must be considered.
Average time
to perform maintenance
Maximum time
to repair equipment (high probability)
Ex: User of equipment may have a requirement that
the equipment be designed so that
Average repair time = 2 hrs
95% of all possible repair actions can be completed in
5 hrs
Overall maintenance time will depend
on?
Time
Time it takes:
Getting access to specific parts
Diagnosing
Repair or replacement
Calibration
Testing
Closing up
The probability that an equipment will be retained
in, or restored to, a specified condition in a given
period of time, when maintenance is performed in
accordance with prescribed
procedures and
resources.
What is Maintainability?
Procedures
Instructions and methods used to perform
maintenance
Manuals on how to perform maintenance
Standard procedure for maintenance
Resources
Skills of individuals performing maintenance
Tools used
Skill level and type of tool
Quantitative Measures
Maintainability Metrics
Maintainability Metrics
Mean Time to Repair (MTTR)
Sample of repair actions
Composite value, arithmetic average of maintenance cycle
times for individual actions
Aka Mean Corrective Maintenance Time
Maximum Active Corrective Maintenance Time (M
max
)
Value of maintenance downtime below which one can
expect a specified percent of all corrective maintenance
actions to be completed.
Maintainability Metrics
Mean Preventative Maintenance Time
Mean Time to Restore System (MTTRS)
For highly redundant systems, the average time needed to
switch to a redundant backup unit
Mean Downtime (MDT)
Average time that a system is not operational due to repair
or preventative maintenance (includes logistics and
administrative delays)
Maintenance Ratio (MR)
Measure of total maintenance labor burden required to
maintain an item
Maintainability Engineering Formulas
Maintainability Functions
Mean Active Maintenance time
λ
= Failure Rate
fpt = Frequency of Preventative Maintenance
Logistics Delay Time (LDT)
Admin Delay Time (ADT)
Categories of Maintenance
1.
Corrective Maintenance:
Unscheduled actions as a result of failure
Necessary to
restore
a system
Troubleshooting, disassembly, repair, remove and
replace, reassembly, alignment and adjustment
2.
Preventative Maintenance:
Scheduled actions necessary to
retain
a system
Periodic inspections, servicing, calibration, condition
monitoring, replacement of designated critical items
Maintainability Measurables
Time
Labor Hours
Maintenance Frequency
Logistical Support Factors
Time
Uptime
Standby/Ready Time
System Operating Time
Downtime
Active Maintenance Time
System not active because of corrective and/or
preventative maintenance activities
Logistics Delay Time
System not active because of logistics delays
Administrative Delay time
System not active because of administrative delays
Active Maintenance Time
1.
Corrective Maintenance
Preparation for Maintenance
Localization and Fault Isolation
Disassembly
Repair Item – Remove Faulty Item and Replace
Reassembly
Adjust, Align, and Calibrate
Verification
Active Maintenance Time (cont.)
2.
Preventative Maintenance
Preparation Time
Inspection Time
Servicing Time
Verification or Check out
Time Relationships
Categorizing the Implementation of a
Maintainability Program
Program, Planning, Management, and Control
Design and Analysis
Test and Evaluation
Program, Planning, Management, and
Control
Maintainability Program Plan
Review and Control of Suppliers or Subcontractors
Maintainability Program Reviews
Data Collection, Analysis, and a Corrective-Action
System
Design and Analysis
Maintainability Modeling
Maintainability Allocation
Maintainability Prediction
Failure Mode, Effect, and Critical Analysis
Maintainability Analysis
Maintenance Task Analysis
Level of Repair Analysis
Maintainability Data for the Detailed Maintenance
Plan and the Supportability Analysis
Test and Evaluation
Maintainability Demonstration
The
Big
Picture
Reliability, Availability and
Maintainability (RAM)
DoD 5000 Series Acquisition Management
Framework
Key Steps to Achieve RAM
1.
Understand and Document User Needs and
Constraints
2.
Design and Redesign for RAM
3.
Produce Reliable and Maintainable Systems
4.
Monitor Field Performance
1. Understand/Document User Needs
and Constraints
Customer: operate, maintain, support capability being acquired
Define desired capabilities to guide development
Mission, system performance, structure, readiness, sustainability,
constraints (logistics, affordability)
Within capability, determine reliability, availability, maintainability
needs of user
Users, system/design/manufacturing engineers, testers develop RAM
Rationale to establish boundaries and guidelines
Consider interaction of system reliability, logistic support, operation
Compare desired RAM levels to RAM performance of current
systems, assess feasibility
Translate operational RAM terms into contractual terms
Provide reliability and maintainability incentives
2. Design and Redesign for RAM
Objectives
Develop comprehensive program for designing and
manufacturing for RAM
Develop conceptual system model (system, subsystem,
components, performance requirements, etc.)
Identify critical failure modes and degradations
Use data from component-level testing to characterize
distribution of times to failure
Conduct analysis to determine if design is capable of
meeting RAM requirements
Design in: diagnostics for fault detection,
isolation/elimination of false alarms
2. Design and Redesign for RAM
Key activities
1.
Implement the right activities at the right time in the right
way
2.
Conduct formal design reviews for reliability and
maintainability
3.
Use an impartial, competent peer for perform the design
review
4.
Use a closed-loop design review process
5.
Emphasize systems engineering design analysis and rely
less on RAM predictions
6.
Fully understand the implications using COTS equipment
2. Design and Redesign for RAM
Key activities
7.
Focus on maintainability and provide sufficient resources
to mature the diagnostic capability
8.
Link design testing and reliability testing
9.
Manage the failure mode mitigation process
10.
Assess the risks and operational impacts before trading
RAM for cost, schedule or other requirements
11.
Address RAM considerations in pre-systems acquisition
technology development activities
12.
Avoid delaying corrective actions
13.
Provide meaningful oversight in executing the contract
3. Produce Reliable and Maintainable
Systems
Focus now on process control, quality assurance,
environmental stress screening
Data provides insight on how well production units
are performing in operational environment
1.
Testing
2.
Quality Assurance
3.
Achieving Initial Operational Capability
3. Produce Reliable and Maintainable
Systems
1.
Testing
2.
Quality Assurance
3.
Achieving Initial Operational Capability
3. Produce Reliable and Maintainable
Systems
1.
Testing
If system has satisfactory levels of RAM
Purpose: learning
Verify if problems from previous phases have been
fixed, solutions incorporated.
3. Produce Reliable and Maintainable
Systems
2.
Quality Assurance
Main RAM concern during manufacturing is to prevent
degradation of inherent reliability, availability and
maintainability design into system during design
phase
Quality & product assurance works with RAM team
More on quality assurance next week!
3. Produce Reliable and Maintainable
Systems
3.
Achieving Initial Operational Capability
Within lifecycle, units are receiving trained manpower,
systems, equipment, support
Working to achieve initial operational capability and
operational availability
Possible problems
Inadequate maintenance training
Unanticipated failure modes
Differences in operational environment from anticipated during
design
RAM team should anticipate, monitor, identify resources to
asses, resolve problems
Key Steps to Achieve RAM
1.
Understand and Document User Needs and
Constraints
2.
Design and Redesign for RAM
3.
Produce Reliable and Maintainable Systems
4.
Monitor Field Performance
4. Monitor Field Performance
Ensure that necessary levels of RAM are sustained
during lifecycle
Reliability and maintainability are drivers of support
and cost of support
Support
Support equipment and tools
Technical data
Training and training support
Computer resource support
Facilities
Packaging, handling, storage, transportation
4. Monitor Field Performance
Performance measures
Mission success rate
Operational availability
Operations and support cost
Do not indicate specific causes of problems
Data collection and analysis will help identify and
prioritize specific RAM problems
Idaho National Laboratory
System Verification through RAM Analysis and
Technology Readiness Levels
Opare Jr. and Park, 2010
RAM Case Study
Introduction
•
Next Generation Nuclear Plant (NGNP) Project
•
The Hydrogen Production System (HPS) Project
•
Identifying and tracking system vulnerabilities during maturation
•
Validating system operational requirements with the end-user in
mind
•
Objective of the RAM guide
•
ensure end-user needs are identified and noted during
system design
•
minimize the risk of developing a system that does not
meet end user operational needs
•
Early stages
of RAM in system development
•
Identify vulnerabilities in the system when deployed
•
Provides decision makers and customers to make early design
alterations
Background
The HPS will utilize a high temperature steam electrolysis (HTSE) system
which uses high temperature heat from a nuclear reactor to split water
into hydrogen and oxygen with no consumption of fossil fuels, no
production of greenhouse gases, and no other forms of air pollution.
High temperature electrolytic water-splitting supported by nuclear
process heat and electricity has the potential to produce hydrogen with
purity levels of 99.99%.
The hydrogen production system is in the conceptual phase of
development and it is during this early design phase that risk mitigation
and RAM improvement activities can be most beneficial to the customer
•
Operational availability of system – most important metric to
customer
•
To track RAM improvement as the system matures while mitigating
risks; a RAM Roadmap was developed
RAM Process Development
A Project-phased process within the Department of
Energy (DOE)
Review conducted to identify documents that contain
requirements for RAM analysis
Documents like INL operations and Management Contract,
DOE orders and guides and international codes and
standards
Requirements extracted from documents and compiled
Some requirements were duplicative or contradictory
Finally a consolidated and reconciled set of applicable
requirements was developed
RAM Process Development –Cont’d
Requirements are time-phased and complicated
necessary to develop a RAM roadmap that diagrammed
the RAM activities
integrated with DOE critical decisions for authorization and
funding
NGNP Project Technology Readiness Levels (TRLs) were
added to guide and correlate technical maturity in
RAM activities
RAM Analysis methods and tools were highlighted with
key deliverable documents to support effective Systems
Engineering.
Technology Readiness Assessment
RAM process provides a visual representation of the
sequential and interrelated activities
HPS project uses Technology Readiness Assessment
(TRA) process to determine technology maturity of
critical systems, subsystems and components.
Technology development activities are done
concurrently along select RAM activities at each
phase of system development
Reliability improves as technology is studied, tested
and matured through design
High Level Technology Maturation Process
Quantification of Customer
Requirements
To translate all loose requirements into quantifiable metrics
Provides the capability to trace system design requirements
through development
In the case of the HPS, system requirements were too broad to
be useful for verification and validation
It implies the consolidation of requirements with similar themes
into some measurable metrics like RAM for verification and
validation purposes
Thus verification and validation work is performed as system
matures through TRL space
Inter-relationship of quantifiable metrics
Mitigating Operational Risk through
RAM Analysis
Reliability
is the probability of an item to successfully
perform a required function under stated conditions
without failure for a specified period of time
Availability
measures the degree to which an item is in
an operable state can be committed to operate at any
point in time
Availability is a function of
How often system failure occurs
How quickly failures can be isolated and repaired
How long logistics support delays contribute to down time
How often preventative maintenance is performed
RAM Inter-relationship Matrix
Mitigating Operational Risk through
RAM Analysis – continued
When system RAM is improved with system development,
system operational risks are reduced
Potential consequences that could result if operational risks
are not mitigated:
Inability to operate the system due to regulatory standards
Increase in system operational cost due to poor system
operational availability
Loss of system throughput due to poor system availability caused
by frequent system failures
Loss of customers for the end-user due to inability to meet
customer demand caused by poor system operational availability
Outputs of RAM analysis
Major outputs of RAM analysis
FCI – Failure Critical Index
TOC – Total Ownership Cost
FCI
identifies the critical entities within the system responsible for majority of
system failures
important to improve system robustness and minimize the availability
challenges of the system when constructed and deployed
TOC
TOC helps estimate the operational cost of the system when in operation
to estimate the cost of owning and operating the system provides the
end-user a way to influence system design and development
Outputs of RAM analysis - continued
The purpose of RAM analysis is to verify that
potential operational risks are mitigated before the
system is constructed and deployed
RAM analysis identify vulnerabilities within the
system which prevent it from fulfilling its mission
Risk Priority Number = (PE x PC) x C x W
where
PE = Probability of occurrence
PC = Probability that consequence occurs at level of severity noted
C = Consequence of occurrence (loss if event occurs)
W = Weighting factor, function of the probability of the event times
consequence
Risk of a system
Operational Risks Graph
Technology Readiness Level (TRL)
and RAM Integration
Technology Readiness Assessment process evaluates the
deployment readiness of a technology and its readiness
to function in an integrated environment
The 10 scale rating allows the project to assess readiness
for full commercialization following the construction and
successful operation
provide input to inform project management of the
readiness of a particular technology, component, or system
As the system matures through TRL space, RAM metrics are
verified to ensure that system maturity equates to RAM
improvement
TRL Scale and Criteria
Application of RAM Analysis at
Conceptual Design
RAM simulation uses real data to simulate the future state of a
system based on current design configurations and component
failure characteristics
Iterative process is used to track the progress of the system towards
stated target operational requirements
RAM analysis at the early stages are challenging, especially when
system components are not clearly defined
Current operational availability requirement of the HTSE is 90% i.e.
the system after construction and development should be
operational 90% of the time during its life.
Application of RAM Analysis at
Conceptual Design - continued
When RAM is adopted at early stages of system development it
drives system design toward an established reliability and
operational availability.
To create a systems description document which identifies the
functions of all the sub-entities of the system and highlights the
interfaces between them
To capture the anticipated performance metrics of the system’s
entities, critical for RAM inputs
In cutting edge HPS system technology, RAM analysis was possible
because the various entities within the system were fundamentally
similar to technologies commercially available today.
RAM complete system process:
Questions?
•
Next Week: Human Factors and Safety
References
The following references are used to compile the slides for this module:
DOD Guide for Achieving Reliability, Availability, and Maintainability
(2005).
Blanchard and Fabrycky (2010). Systems Engineering and Analysis (5
th
Edition). Published by Prentice Hall.
Faulconbridge and Ryan (2003). Managing Complex Technical Projects: A
Systems Engineering Approach. Published by Artech House, Inc.
Blanchard (2008). Systems Engineering Management. 4
th
Ed., Published by
Wiley Series
Kossiakoff, Sweet, Seymour and Biemer (2011). Systems Engineering
Principles and Practice. Wiley.
Buede (2009). The Engineering Design of Systems: Models and Methods.
Wiley.
Sage and Armstrong (2000). Introduction to Systems Engineering. Wiley.
NASA Systems Engineering Handbook, 1995, 2007
Availability and maintainability are crucial aspects in engineering, defining the system's operable state and its ability to fulfill missions. Availability is the probability of the system being operational when called for, contingent on factors such as failure occurrence, maintenance frequency, and repair efficiency. It necessitates a clear understanding of operational guidelines, maintenance policies, and supply system responsiveness. Availability metrics encompass factors like failures, reliability, maintenance resources, and personnel skills. The concept of availability is further categorized into three types: inherent, achieved, and operational. Inherent availability signifies the system's operational duration without maintenance, calculated using mean time between failures and mean time to repair.
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Presentation Transcript
SENG 5232 ENGINEERING SPECIALTY INTEGRATION AVAILABILITY MAINTAINABILITY RAM CASE STUDY
Today Availability Maintainability RAM Case Study
What is Availability? Measure of the degree to which an item is in an operable state and can be committed at the start of a mission when the mission is called for at an unknown (random) point in time. Simple Translation: The probability that the system is operation or available at time t.
What is Availability? A function of: 1. How often failures occur and corrective maintenance is required 2. How often preventative maintenance is performed 3. How quickly indicated failures can be isolated and repaired 4. How quickly preventative maintenance tasks can be performed 5. How long logistics support delays contribute to down time.
Availability Requires a description of how the item/system is to be used. How item will be operated Maintenance policy Maintenance concept Adequacy and responsiveness of the supply system Affected by how often a system becomes unusable and how long it takes to restore
Availability Metrics Elements that determine availability Failures Inherent level of reliability built into the system Maintenance Corrective and preventative Length of time required Resources Maintenance personnel available Skill and K of personnel # and availability of spare/repair parts, support equipment, etc.
Availability Three types of availability Inherent Availability Achieved Availability Operational Availability
Inherent Availability Probability the system (when used properly) will operate satisfactorily for a period of time without maintenance Does not include preventative or scheduled maintenance AI = MTBF(MTBF + MTTR) 1 MTBF: Mean Time Between Failure MTTR: Mean Time To Repair
Achieved Availability Probability the system (when used properly) will operate satisfactorily for a period of time Preventative or scheduled maintenance is included AA = MTBM(MTBM + MAMT) 1 MTBM mean time between maintenance MAMT mean active maintenance time
Operational Availability Probability the system (when used properly) will operate satisfactorily for a period of time when it is called upon Preventative or scheduled maintenance is included AO = MTBM(MTBM + MMDT) 1 MTBM mean time between maintenance MMDT mean maintenance down time
Inherent vs. Operational Availability Measure Equation Factors MTBF + = Ai MTBF: Mean Time Between Failure MTTR: Mean Time To Repair MTBF MTTR Inherent MTBM = A MTBM: Mean Time Between Maintenance MDT: Mean Downtime 0 + MTBM MDT Operational
Availability, Simplified Availability is measured in terms of uptime and downtime. Operational availability: Time during which system was capable of performing all required functions in a given interval Uptime 0= A Total Time Time during which system was supposed to be up during a given interval (Uptime + Downtime) Downtime Waiting for spare parts to arrive via supply chain (logistics downtime) Time to repair (maintenance time, queue for maintenance)
Question: Module 5 Exercise 5 Can a product with identical failures (rates and events) have different perceived or measured availability for different customers?
What is Maintainability? The probability that an equipment will be retained in, or restored to, a specified condition in a given period of time, when maintenance is performed in accordance with prescribed procedures and resources.
What is Maintainability? The probability that an equipment will be retained in, or restored to, a specified condition in a given period of time, when maintenance is performed in accordance with prescribed procedures and resources. Probability: Proportion (or % of the time) that a maintenance task is performed in a specified time. This probability will depend on?
Probability The way equipment is designed The tools available The skill of the person doing the repair The environment Technical manuals Ease of doing trouble shooting Getting access to the critical area Motivation of the person doing the repair
What is Maintainability? The probability that an equipment will be retained in, or restored to, a specified condition in a given period of time, when maintenance is performed in accordance with prescribed procedures and resources. Retained in, or restored to: Preventative or corrective maintenance. With either, the equipment is brought back to original condition.
What is Maintainability? The probability that an equipment will be retained in, or restored to, a specified condition in a given period of time, when maintenance is performed in accordance with prescribed procedures and resources. Condition: Original design level. Some degradation of system is expected, e.g. car.
What is Maintainability? The probability that an equipment will be retained in, or restored to, a specified condition in a given period of time, when maintenance is performed in accordance with prescribed procedures and resources. Time: Time it takes to perform the maintenance. Is a function of equipment design.
Time When equipment is designed, length of time maintenance is going to take must be considered. Average time to perform maintenance Maximum time to repair equipment (high probability) Ex: User of equipment may have a requirement that the equipment be designed so that Average repair time = 2 hrs 95% of all possible repair actions can be completed in 5 hrs Overall maintenance time will depend on?
Time Time it takes: Getting access to specific parts Diagnosing Repair or replacement Calibration Testing Closing up
What is Maintainability? The probability that an equipment will be retained in, or restored to, a specified condition in a given period of time, when maintenance is performed in accordance with prescribed procedures and resources.
Procedures Instructions and methods used to perform maintenance Manuals on how to perform maintenance Standard procedure for maintenance
Resources Skills of individuals performing maintenance Tools used Skill level and type of tool
Maintainability Metrics Quantitative Measures
Maintainability Metrics Mean Time to Repair (MTTR) Sample of repair actions Composite value, arithmetic average of maintenance cycle times for individual actions Aka Mean Corrective Maintenance Time ct M Maximum Active Corrective Maintenance Time (Mmax) Value of maintenance downtime below which one can expect a specified percent of all corrective maintenance actions to be completed.
Maintainability Metrics Mean Preventative Maintenance Time Mean Time to Restore System (MTTRS) For highly redundant systems, the average time needed to switch to a redundant backup unit Mean Downtime (MDT) Average time that a system is not operational due to repair or preventative maintenance (includes logistics and administrative delays) Maintenance Ratio (MR) Measure of total maintenance labor burden required to maintain an item M pt
Maintainability Engineering Formulas Maintainability Functions Mean Active Maintenance time = Failure Rate fpt = Frequency of Preventative Maintenance Logistics Delay Time (LDT) Admin Delay Time (ADT) ( )(Mct) + (fpt)(Mpt) M= + fpt
Categories of Maintenance Corrective Maintenance: Unscheduled actions as a result of failure Necessary to restore a system Troubleshooting, disassembly, repair, remove and replace, reassembly, alignment and adjustment Preventative Maintenance: Scheduled actions necessary to retain a system Periodic inspections, servicing, calibration, condition monitoring, replacement of designated critical items 1. 2.
Maintainability Measurables Time Labor Hours Maintenance Frequency Logistical Support Factors
Time Uptime Standby/Ready Time System Operating Time Downtime Active Maintenance Time System not active because of corrective and/or preventative maintenance activities Logistics Delay Time System not active because of logistics delays Administrative Delay time System not active because of administrative delays
Active Maintenance Time 1. Corrective Maintenance Preparation for Maintenance Localization and Fault Isolation Disassembly Repair Item Remove Faulty Item and Replace Reassembly Adjust, Align, and Calibrate Verification
Active Maintenance Time (cont.) 2. Preventative Maintenance Preparation Time Inspection Time Servicing Time Verification or Check out
Reliability, Availability and Maintainability (RAM) The Big Picture
DoD 5000 Series Acquisition Management Framework
Key Steps to Achieve RAM 1. Understand and Document User Needs and Constraints 2. Design and Redesign for RAM 3. Produce Reliable and Maintainable Systems 4. Monitor Field Performance
1. Understand/Document User Needs and Constraints Customer: operate, maintain, support capability being acquired Define desired capabilities to guide development Mission, system performance, structure, readiness, sustainability, constraints (logistics, affordability) Within capability, determine reliability, availability, maintainability needs of user Users, system/design/manufacturing engineers, testers develop RAM Rationale to establish boundaries and guidelines Consider interaction of system reliability, logistic support, operation Compare desired RAM levels to RAM performance of current systems, assess feasibility Translate operational RAM terms into contractual terms Provide reliability and maintainability incentives
2. Design and Redesign for RAM Objectives Develop comprehensive program for designing and manufacturing for RAM Develop conceptual system model (system, subsystem, components, performance requirements, etc.) Identify critical failure modes and degradations Use data from component-level testing to characterize distribution of times to failure Conduct analysis to determine if design is capable of meeting RAM requirements Design in: diagnostics for fault detection, isolation/elimination of false alarms
2. Design and Redesign for RAM Key activities 1. Implement the right activities at the right time in the right way 2. Conduct formal design reviews for reliability and maintainability 3. Use an impartial, competent peer for perform the design review 4. Use a closed-loop design review process 5. Emphasize systems engineering design analysis and rely less on RAM predictions 6. Fully understand the implications using COTS equipment
2. Design and Redesign for RAM Key activities 7. Focus on maintainability and provide sufficient resources to mature the diagnostic capability 8. Link design testing and reliability testing 9. Manage the failure mode mitigation process 10. Assess the risks and operational impacts before trading RAM for cost, schedule or other requirements 11. Address RAM considerations in pre-systems acquisition technology development activities 12. Avoid delaying corrective actions 13. Provide meaningful oversight in executing the contract
3. Produce Reliable and Maintainable Systems Focus now on process control, quality assurance, environmental stress screening Data provides insight on how well production units are performing in operational environment Testing Quality Assurance Achieving Initial Operational Capability 1. 2. 3.
3. Produce Reliable and Maintainable Systems 1. Testing 2. Quality Assurance 3. Achieving Initial Operational Capability
3. Produce Reliable and Maintainable Systems 1. Testing If system has satisfactory levels of RAM Purpose: learning Verify if problems from previous phases have been fixed, solutions incorporated.
3. Produce Reliable and Maintainable Systems 2. Quality Assurance Main RAM concern during manufacturing is to prevent degradation of inherent reliability, availability and maintainability design into system during design phase Quality & product assurance works with RAM team More on quality assurance next week!
3. Produce Reliable and Maintainable Systems 3. Achieving Initial Operational Capability Within lifecycle, units are receiving trained manpower, systems, equipment, support Working to achieve initial operational capability and operational availability Possible problems Inadequate maintenance training Unanticipated failure modes Differences in operational environment from anticipated during design RAM team should anticipate, monitor, identify resources to asses, resolve problems
Key Steps to Achieve RAM 1. Understand and Document User Needs and Constraints 2. Design and Redesign for RAM 3. Produce Reliable and Maintainable Systems 4. Monitor Field Performance
4. Monitor Field Performance Ensure that necessary levels of RAM are sustained during lifecycle Reliability and maintainability are drivers of support and cost of support Support Support equipment and tools Technical data Training and training support Computer resource support Facilities Packaging, handling, storage, transportation
