Post on 30-Jun-2020
Introduction to Reliability Centred Maintenance
Keith Ashington
M.Eng CM.EngNZ C.Eng M.ICE
Summary
• Background
• What is RCM2?
• The RCM2 process
• Application to track assets
• Benefits
Background
Initial assumptions
• Every aircraft has a specific ‘life’
• Every major component has a specific ‘life’
• Servicing carried out just before ‘life’ reached
• Life can be predicted / defined
• Reducing service life increases reliability
Study findings
What is RCM2?
“A process used to determine what must be done to ensure that any physical asset
continues to do what is users want it to do in its present operating context”
Further publications
RCM2 in the UK rail network
• NR/L2/SIG/10662
• NR/L2/MTC/10662
The RCM2 Process
FMECA+
Workshop
RCM2
Facilitator
Engineering Supervisor
Operative
External specialist
Operator
Operations Supervisor
Operating Context
Stage 1 - Function
• “What are the functions and associated performance standards of the asset in its present operating context?”o “To…
o …Verb…
o …Noun…
o …Performance Standard”
• Primary Function
• Secondary function
Stage 2 - Functional Failure
• In what ways does it fail to fulfil its functions?
Stage 3 - Failure modes
• What causes each functional failure?
Stage 3 - Failure modes
Stage 4 - Failure effects
• What happens when each failure occurs?
• Identifies potential failure points
• Defect may not become observable
100% Capability
Starts to degrade
Defect becomes
observable
Further degradation
Failure
Stage 5 - Failure Consequences
• Hidden Consequence • Safety / Environmental consequence
Stage 5 - Failure Consequences
• Operational • Non-operational
Stage 6 - On-condition tasks
• Predictive / Preventative
• Defects lead to Faults
o P = potential for failure identified (Defect)
o F = failure identified (Fault)
o P-F = inspection interval + rectification period
Typical on-condition tasks
KiwiRail example – track geometry
• Rectification periodso P4 = 13 weeks
o P3 = 2 weeks
o P2 = 3 days
o P1 = 1 days
o U1 = FAIL
• BUT P2 requires TSR, so failure.
• Very little time to plan rectification
• Inspection Intervalso Class A(M) = 17 weeks
o Class A(NM) = 26 weeks
o Class B = 35 weeks
o Class C = 52 weeks
KiwiRail P-F Intervals
P4 P3 P2 P1 U1
Class A(M) 30 weeks 19 weeks 17.3 weeks 17.1 weeks 17.0 weeks
Class A(NM) 39 weeks 28 weeks 26.3 weeks 26.1 weeks 26 weeks
Class B 48 weeks 37 weeks 35.3 weeks 35.1 weeks 35 weeks
Class C 65 weeks 54 weeks 52.3 weeks 52.1 weeks 52 weeks
• P-F Interval = inspection interval + rectification period
• More time needed to rectify
o Reduce inspection interval
o Find P5
Stage 7 - Scheduled tasks
• On-condition tasks not possible
• Still a risk of failure
• Discard
• Restoration
Stage 8 - Default Actions
• Hidden Consequenceso Failure finding tasks
• Safety / Environmental consequenceso Compulsory re-design
• Operational / Non-operationalo Desirable re-design
o Do nothing
Implementation
• Improved Maintenance Regime
o On-condition Tasks
o Scheduled Tasks
o Re-designs
o Failure finding tasks
Improved Maintenance
Regime
Professional Head Approval
Implementation
Review
RCM2 analysis of track assets
• Exeter - Barnstaple
• Bristol - Exeter
• Euston – Rugby
• Bletchley – Bedford
• Paddington -Heathrow
• Etc
RCM2 analysis - findings
• Consequences o Hidden – Low (Buffer stops, guard rails)
o Safety / environmental - high (Wrong side failures)
o Operational – low (Right side failure, IBJ)
o Non-operational – low (Wheel squeal)
• On-condition taskso Already in place
o Changes in frequency
o Changes in rectification periods
Changes to on-condition tasks
• All inspections intervals and periods justified
Inspection Change
Patrolling Removed
SM(T) Inspections Replaced with verifications
TME Inspections Maintained (Assurance)
Track Geometry recording
Non-mandated AL faults became mandated
Ultrasonic inspections Non-mandated faults became mandated, all suspects verified
Structure Gauging No change (ORR mandated)
Grinding No change
Lubrication No change
Impact on traditional track
• On condition taskso Small P-F
o Worth doing?
• scheduled restorationso Screw tightening
o Lubrication
o Joint adjustment
o Fastening maintenance
• Default actionso Redesign (Modern track)
• Operating context
o Low tonnage
o Low speed
o Low spend!
Impact on modern track
• On-condition taskso Automated
o Fewer visual inspections
• Scheduled Restorationso Grinding
o Rail lubrication
• Scheduled Discardso Re-padding
• Default actionso Turnout redesigns
Results of RCM2 analysis
• Greater reliance on automated systems
• Targeted track patrolling / verifications
• Maintenance backlog reduced
• Opex reduction
• Risk reduction
Do we need to patrol at all?
• Safety risk on site
• Safety risk travelling to site
• Age / fitness
What can be achieved?
Thank you!
Questions?
Keith Ashington CM.EngNZ, C.Eng M.ICE