2. Performance Center Maintenance in 4 steps
PCM, based on RBM, is a way of looking at maintenance in
such a way that optimal maintenance is executed given
customer (rolling stock operators) demands on performance and cost. Since customer demands are not static but dynamic
given the time of the year, economic climate etc., maintenance
will also be dynamic.
In this chapter we will present a 4 step approach to deal with
this dynamic maintenance concept.
2.1. Step 1: agree on risks
Risks on safety are obvious, but there are also risks on
reliability loss, availability, image, quality and cost. In fact,
the responsibility for these risks aspects is not NedTrain’s, but
primarily the Transport Operator’s. The first question to be
asked is: ”what risks is the operator prepared to accept”?.
Knowing these risk limits NedTrain is able to set up and
modify the necessary maintenance policy. This first step might
be obvious, but is hard to take in practice.
x In general, rolling stock performance, and thus
maintenance, is contracted on a high level, in terms of
‘number of safety issues’, ‘number of unavailable train
sets’, ‘number of unplanned depot entries’. These KPI’s
are mostly interrelated, but are all these relations known?
And what does this mean in terms of a risk matrix or
other methods such as Fine and Kinney (F&K) [1])? Is
safety equally important as availability or reliability?
x How strong is the gut-feeling on safety, related to image?
When transforming the number of safety issues into
number of fatalities, as is used in the F&K-method, it will
lead to a given acceptance level. When - unfortunately -
an incident occurs, public opinion and politicians will try
to increase this safety level without accepting a higher
cost level for maintenance.
In practice we work with an officially excepted safety risk
matrix between the operator and NedTrain, combined with the
agreed performance criteria and cost, whilst improving the
risk matrix on management level. Important point is that there
is a mutual understanding of the starting point of maintenance.
2.2. Step 2: to train Maintenance Engineers
In our opinion one of the reasons many RBM approaches
fail, is because of a ‘jumping to expensive software tools’,
without knowing exactly what to do with it. For this reason
we started with developing our own tools in Excel, and
training our maintenance engineers (in the specific NedTrain
case we consider at least two roles in maintenance: the
maintenance engineer, responsible for the cost efficient and
effective ‘maintenance manual’ of a train type, and the
reliability engineer, responsible for the analysis and
improvement of the performance of a certain train type).
Although time consuming, it gave us the correct insights in
the details of FMECA (Failure Modes, Effects, Criticality
Analysis), of maintenance interval optimization and rolling
stock performance improvement, paying off in quick wins on
performance.
2.3. Step 3: Prioritize
A RBM-approach tends to be time-consuming. To
complete the analysis, technical data need to be gathered on
each component involved in a certain function, its failure rate,
understanding of its function, failure mechanisms,
consequences of failures in terms of risks, optimal
maintenance strategy etc. In one function of a system several
hundred components might be involved, taking it months of
study, capacity of engineers and mechanics.
In our approach we start with answering the question what
systems and subsystems, which function losses contribute
most to performance, cost and risks, thus creating a natural
order of handling. In case of cost, figure 2 shows a typical
order.
2.4. Step 4: take the operation plan into account
When preparing maintenance for new train types, decisions
are made on work to be done during daily inspections, short
term maintenance and overhaul. This distribution of work will
normally be done based on expertise, available equipment and
tooling.
While performing an PCM-analysis on maintenance, the
question may be posed whether earlier choices are still valid
Could it be possible for instance to gain on availability by
inspecting more frequently during natural off-service periods
rather than during planned maintenance in a depot? When
utilizing a depot, train sets normally will be unavailable for
approximately 60-70 hours, influenced by inspection based
maintenance and successive unplanned maintenance. For this
reason, during the analysis we assess the possibilities of
rescheduling work to other locations.