Transcript Repeating Design Errors or “Where`s the History?”

Repeating Design Errors
or
“Where’s the History?”
Randal D. Bennett
University of Maryland
University College
805 Montview Dr
Escondido CA 92025
[email protected]
Crystal D. Sloan
EagleRidge Technologies, Inc.
114 Ledgerwood Lane
Rockwood, TN 37854
[email protected]
Copyright © 2003 Randal Bennett and Crystal
Sloan
History in the Making:
The Original Error:
Oliver Hazard Perry-Class Frigates
1977
Fault-prone
Engineering Control System
Copyright © 2003 Randal Bennett and Crystal
Sloan
Engineering Control
System (ECS)
• Shielded wire-braid cable with
shielding that naturally degrades
over time
• Ungrounded, interconnected busses
• Low-voltage digital alarm/control
systems
Copyright © 2003 Randal Bennett and Crystal
Sloan
Boundary Condition –
Setup
Exterior
Exterior
Insulation
Insulation
Wire
WireBraid
Braid
Sheathing
Sheathing
Shielding
Shielding
Individual
Individual
Insulated
Insulated
Conductors
Conductors
Copyright © 2003 Randal Bennett and Crystal
Sloan
Boundary Condition –
Boundary Condition
Setup
Result – Result
Copyright © 2003 Randal Bennett and Crystal
Sloan
Focus on Nominal Behavior:
Collocation of Redundant Elements
Propulsion
Control
Console
Bus
Wiring
Harness
Auxiliary
Control
Console
Alarm on
ACC
Bus
Wiring
Harness
Electric Plant
Control
Console
Copyright © 2003 Randal Bennett and Crystal
Sloan
Grounded
Shield
Focus on Nominal Behavior:
Requirements vs. Usage
• Requirement: sea water (heat sink)
temperature - Design: 85F, Actual: 95F
• Support system impacted: air conditioning
plant
• Impact: reduced heat rejection
• System impact: elevated cabinet
temperatures
• Result: degraded circuit cards,
processors and power supplies
Copyright © 2003 Randal Bennett and Crystal
Sloan
Focus on Nominal Behavior:
Failure to Anticipate System
Deterioration Over Time
• Causes of cable deterioration
– Vibration
– Retention of a low-cost vessel
– Insufficient allocation of
maintenance funds
Copyright © 2003 Randal Bennett and Crystal
Sloan
History Repeats:
Arleigh Burke-Class
Destroyers
1991
Repeated design error:
Fault-prone Machinery Control
System
Copyright © 2003 Randal Bennett and Crystal
Sloan
Machinery Control System
• Shielded wire-braid cable
• Ungrounded, interconnected
busses
• Low-voltage digital alarms/controls
• Reliance on air conditioned spaces
Copyright © 2003 Randal Bennett and Crystal
Sloan
Machinery Control System
• Prerequisites for failure duplicated
• Failures evident now
• Design activity – strong
performance
• Why the repetition?
Copyright © 2003 Randal Bennett and Crystal
Sloan
Studying History
“Those who cannot remember the past
are condemned to repeat it.”
Jorge Santayana (1905)
• Lack of accessible history
Copyright © 2003 Randal Bennett and Crystal
Sloan
Current Maintenance Data
Collection System
• Resistant to data mining
– Information buried in text blocks
– Lack of refined hierarchical structure
– Inconsistent naming practices
• Violates Degregorio’s critical
elements
– “… information architecture with
internal structures …”
• Self-perpetuating
Copyright © 2003 Randal Bennett and Crystal
Sloan
Other Tools
• Casualty Reporting (CASREP)
System
• Quality Deficiency Report (QDR)
• Parts Usage
• Troubled Systems Process (TSP)
• Management processes
– Top Management Attention
– Top Management Interest
Copyright © 2003 Randal Bennett and Crystal
Sloan
Solutions
• For legacy and future data: index and
make available using search engine
technology
– Very low cost solution
• For future data: System design
change
Copyright © 2003 Randal Bennett and Crystal
Sloan
Search Engine Technology
• Establish view to data
• Dynamic web page
– Search string text box
– Embedded link to first record
– Link to next record
• Search appliance
– “Crawls” database
– Maintains data security
Copyright © 2003 Randal Bennett and Crystal
Sloan
System Design Change
• Data architecture discipline
• Scripted Standardized Assessment
Procedures
Copyright © 2003 Randal Bennett and Crystal
Sloan
Data Architecture Discipline
• Realignment of Hierarchical Structure
Code (HSC)
– Identical code for same equipment in
same application
– Standardized across classes and ships
– Expanded to cover all components
• Standardized nomenclature
Copyright © 2003 Randal Bennett and Crystal
Sloan
Benefits of Discipline
• Ensures visibility of common issues
• Reduces configuration labor at ship
design time
• Foundation for data warehousing
• Supports Standardized Scripted
Assessment Procedures
Copyright © 2003 Randal Bennett and Crystal
Sloan
Benefits of SSAP
• Ensures correct equipment
reported
• Reduces maintenance-induced
failures
• Provides management functions
– Tool inventory
– Materials requirements
Copyright © 2003 Randal Bennett and Crystal
Sloan
Data Warehousing
• Stores results of SSAP
• Organized structure promotes
mining
• Renders history available
Copyright © 2003 Randal Bennett and Crystal
Sloan
End Result
• Fleet-wide view of ship material
condition
• Universal material condition assessment
process
• Improved accuracy and drill-down detail
• Iterative improvement in existing data
collection
• Continuum of assessment process
improvement
Copyright © 2003 Randal Bennett and Crystal
Sloan