October - Library - Central Queensland University

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Backlog
Backlog is one of the key metrics that indicates how well the maintenance organization stays on top of its workload level. A backlog
of demand driven jobs gives the Planner/Scheduler the opportunity to properly balance and distribute the workforce to meet all
operational requirements. A backlog that is too high means that the workforce cannot do the work within a reasonable period and
that some important jobs, such as preventive maintenance, are not done. On the other hand, a backlog that is too low means that
the workforce cannot be effectively utilized and the probability of excessive manpower is fairly high. A backlog of 2 to 4 week of
ready to work jobs is a reasonable level to keep the workforce occupied and still meet the equipment demands.
Backlog is derived by dividing the total estimated man-hours on all ready to work jobs by the available man-hours for the week.
The backlog trend is the key factor, and a chart such as shown in Figure 5 will help the Maintenance Manager make personnel
adjustments as necessary. If the backlog has a tendency to peak during short intervals, outside contracting is the best way to
stabilize the backlog trend. The backlog trend also indicates where to schedule preventive maintenance jobs to best take advantage
of dips in the workload level. While Figure 5 only shows total backlog, the Maintenance Manager would find it advantageous to
show backlog by individual crafts or areas of the plant.
The metric is calculated as follows:
Figure 5
Total Estimated Hours Ready to Work
Backlog in Crew Weeks = ------------------------------------------------------
Total Hours Available for Week
A long-term rise in the backlog indicates the need for additional craftspeople; conversely, a long-term drop in the backlog indicates
the possible need to reduce staff. Decisions of this magnitude must take into consideration future expansion or alterations plans
of the facility or production operations.
A second helpful backlog figure is the total crew weeks of work waiting to be executed, including those jobs for which all the
resources are not yet available. This backlog should average between 5 to 6 crew weeks of work.
Emergencies and Overtime
The percent of emergencies and the percent of overtime are key factors in judging the perf o rmance of the maintenance org a n i z a t i o n .
The chart shown in Figure 6 shows these metrics. Overtime should be kept within 5% of all regular hours worked. Emergencies
re p resent an interruption to the weekly work schedule and work efficiency is decreased. There f o re, jobs classified as emerg e n c i e s
should be kept to less than 10% of all work executed by the maintenance organization. Otherwise, the benefits of the planning and
scheduling process cannot be achieved. (It is decidedly unlikely that true emergencies will routinely amount to more than 10% of
all work, otherwise there are reliability issues that need to be addressed).
Figure 6