copyright © 2003 randal bennett and crystal sloan randal d. bennett university of maryland...

Copyright © 2003 Randal Bennett and Crystal Sloan

Randal D. BennettUniversity of MarylandUniversity College805 Montview DrEscondido CA [email protected]

Crystal D. SloanEagleRidge Technologies, Inc.

114 Ledgerwood LaneRockwood, TN 37854

[email protected]

Repeating Design Errorsor

“Where’s the History?”


The Original Error:Oliver Hazard Perry-Class Frigates1977

Fault-proneEngineering Control System

History in the Making:


Engineering Control System (ECS)

• Shielded wire-braid cable with shielding that naturally degrades over time

• Ungrounded, interconnected busses• Low-voltage digital alarm/control

systems


Boundary Condition – Setup

ExteriorInsulation

Wire BraidSheathing

Shielding

IndividualInsulated

Conductors

ExteriorInsulation

Wire BraidSheathing

Shielding

IndividualInsulatedConductors


Boundary Condition – SetupBoundary Condition – ResultBoundary Condition –

Result


Focus on Nominal Behavior:Collocation of Redundant Elements

Propulsion ControlConsole

Electric PlantControl Console

Bus Wiring

Harness

GroundedShield

Bus Wiring

Harness

Au

xili

ary

Co

ntr

ol

Co

nso

le

Alarm onACC


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


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


Repeated design error:Fault-prone Machinery Control System

History Repeats:

Arleigh Burke-Class Destroyers1991


Machinery Control System

• Shielded wire-braid cable

• Ungrounded, interconnected busses

• Low-voltage digital alarms/controls

• Reliance on air conditioned spaces


Machinery Control System

• Prerequisites for failure duplicated

• Failures evident now

• Design activity – strong performance

• Why the repetition?


“Those who cannot remember the past are condemned to repeat it.”

Jorge Santayana (1905)

• Lack of accessible history

Studying History


Current Maintenance DataCollection 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


Other Tools

• Casualty Reporting (CASREP) System

• Quality Deficiency Report (QDR)

• Parts Usage

• Troubled Systems Process (TSP)

• Management processes– Top Management Attention– Top Management Interest


Solutions

• For legacy and future data: index and make available using search engine technology– Very low cost solution

• For future data: System designchange


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


System Design Change

• Data architecture discipline

• Scripted Standardized Assessment Procedures


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


Benefits of Discipline

• Ensures visibility of common issues

• Reduces configuration labor at ship design time

• Foundation for data warehousing

• Supports Standardized Scripted Assessment Procedures


Benefits of SSAP

• Ensures correct equipment reported

• Reduces maintenance-induced failures

• Provides management functions– Tool inventory– Materials requirements


Data Warehousing

• Stores results of SSAP

• Organized structure promotes mining

• Renders history available


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 randal d. bennett university of maryland...

Documents

crystal sloan randal

randal bennett

crystal sloan focus

history slide

acc slide

system deterioration

sloan eagleridge technologies

power supplies slide