
 
capabilities.  They also have to respond to unplanned 
breakdowns as part of their support mission.  
  
The R&O planning process starts with the 
equipment fleet manager supplying the R&O facility 
with a list of equipments to be overhauled in the 
future. Requirement’s horizon can range from 
months to 10 years depending on the nature of the 
projects.  As part of their business and budgeting 
plan, each R&O facility defines the maintenance 
content to be performed and then it uses them to 
determine the sequence of all activities in a project.  
Based on its current capacity, the facility establishes 
a maintenance program that specifies the estimated 
starting and ending dates of every project and a 
detailed budget.   
 
When all the maintenance program budgets are 
approved at the fleet manager level, a detailed 
production plan is built by allocating the limited 
pool of resources to each project.  Different 
production plans using different resource and 
equipment levels are simulated and tested in order to 
obtain a feasible plan that results in good utilization 
of resources and also meets the customer’s 
expectations.  When the proposed plan is approved 
by the customers, it is used as the master production 
schedule for the next fiscal year.
 
3.2 R&O execution process 
The R&O execution process includes the realization 
of both unplanned repairs and planned 
remanufacturing projects.  For a typical overhaul 
project, work starts with a disassembly activity.  The 
project content is defined as the main equipment is 
inspected (Gharbi et al., 1998).  The next step, the 
most important in terms of workload, includes the 
replacement and repair of a large number of parts 
and components. At the same time, the main 
structure of the equipment can be overhauled and 
modified to accept the new components and the 
repaired ones.  The remanufacturing process then 
ends with the assembly and a final inspection. Such 
projects may also include paint stripping and 
painting operations.   
 
The network or routing topology of a 
remanufacturing project is therefore divergent at its 
start, followed by many parallel paths representing 
the repair of systems or components, and converges 
at the end (Gharbi et al., 1999).  It is important to 
note that not all MRPII or ERP systems can support 
that type of work sequence and its related bill of 
material (Pellerin, 1997).   
 
The other element of complexity when executing 
and controlling a repair and overhaul project resides 
in the nature of each maintenance operation.  The 
amount of work depends on the specific condition of 
the component being repaired or rebuilt.  Therefore, 
the exact duration of any repair is never known 
before its end.  The highly stochastic behavior of a 
repair operation is also responsible for a high 
variability in material consumption.  Inventory 
management for spares parts is extremely difficult in 
that context.  Parts usage must be planned according 
to the maintenance program and based on historical 
consumption data.
   
3.3 Integrating R&O management 
process into ERP 
Maintenance has always been considered as a supp: 
ort function and rarely as a core enterprise process.  
Consequently, most software development 
companies have spent relatively little time and 
efforts at integrating the maintenance processes into 
their MRPII (Ip et al., 2000) or ERP applications 
(Nikolopoulos et al., 2003).   
 
Although the role of maintenance has become 
more important in the last few years, most ERP 
providers still position their maintenance 
management system or module as an execution 
system.  This may be acceptable for traditional 
manufacturing companies but it comes short to 
satisfy all the needs of purely maintenance 
organization such as a remanufacturing or an R&O 
plant.  These organizations need to integrate all 
levels of their planning activities, from the strategic 
business plan to the actual detailed maintenance 
plan. This process requires planning, negotiating, 
sourcing, inventory controlling, scheduling, 
monitoring, quality assurance, and dispatching of the 
necessary resources (Nikolopoulos et al., 2003).  
They also need to be able to translate a customer 
requirement into a firm order with an expected 
delivery date.    This is not an easy task because of 
the stochastic nature of any major maintenance 
request, as described earlier. 
 
 In the case of a defense R&O organization, the 
management complexity increases with the length of 
the planning horizon. Remanufacturing and overhaul 
projects are planned at the fleet level and with 
relatively few information at the equipment level.  
The generic sequence of work is known with 
certainty but this is not the case with the material 
consumption and the work duration.  In practice, 
ERP applications are usually good at composing 
with the changing nature of a maintenance order but 
ADAPTING ERP SYSTEMS FOR SUPPORTING DEFENSE MAINTENANCE PROCESSES
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