Fishbone has worked closely with Porterbrook Leasing Company and South Western Railway to investigate maintenance optimisation on legacy fleets. Significant operational and financial benefits were achieved on the Class 458/5 fleet by extension of the C4 overhaul mileage.


Client: Porterbrook Leasing Limited

Location: UK

Services: Engineering

Fishbone was asked by Porterbrook to develop a methodology to evaluate the existing C4 overhaul, and through a risk-based process and trial running, recommend and gain approval for achieving a significant mileage increase between C4 overhaul periods.

Fishbone delivered a 120,000 mile C4 overhaul increase by:

  • Reviewing current C4 component maintenance and condition at overhaul.
  • Establishing a safe, monitored mileage extension trial
  • Reassessing component condition at extended mileages and presenting a case for extension based on expert condition assessment and mitigations
  • Overhaul maintenance tasks were reviewed for suitability to run to extended mileages themselves based on unit maintenance histories and failure modes
  • A controlled programme of trial running was conducted to ascertain any requirements for change to wear limits, component inspections, and task periodicity
  • Proposal for changes to C4 periodicity was presented to the TOC / ROSCO supporting the changes and other interventions required to optimise the overall benefit
  • The fleet was certified to run extend mileages for both regimes
  • The C4 overhaul periodicity was increased from 600,000 miles to 720,000 miles

Fishbone has successfully completed similar on other fleets for Porterbrook and SWR and are currently undertaking a series of maintenance optimisation reviews for Porterbrook to optimise C6 overhaul either as wholesale maintenance regime change or extended, reduced scope C6 periodicity.

How can we help?

Luke Essex

Head of Project Engineering View Profile

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