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Level Of Repair Analysis (LORA)
The Level Of Repair Analysis (LORA) is instrumental in providing an optimized maintenance
philosophy based upon a cost rational. This analysis can be implemented as a standalone
analysis, but is
generally
integrated in the
Logistics Support
Analysis on an
iterative basis.
The LORA can be
considered as a
two-stage
process that
determines
where an item is
destined to be
repaired and to what level. The results of the LORA process are based upon an economic and
non-economic rational. The LORA can be conducted as an economical or non-economical LORA,
or both.
If an economical LORA (ELORA) is implemented, then as a prerequisite an non-economical (or
screening) process would be implemented. This screening process will minimize the candidates,
who are subject to a ELORA.
Generally the candidates would be selected and worked in conjunction with the maintenance
concept. The maintenance concept would provide details about the lines (or level) of
maintenance and what type of maintenance activities are to be implemented at each line of
maintenance.
The objective of the ELORA, when performed correctly, is to determine the optimum cost of
repair of an end item/equipment, by taking into consideration all associated support cost
drivers (e.g., manpower, support equipment, training, transportation, etc.) that would be
required at each line of maintenance. There is an element in the LORA process that must not be
overlooked, that is the Sensitivity Analysis. Varying different LCC cost drivers will determine
their impact on the model's repair decisions.
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Non-Economical LORA
The non-economic LORA is based upon a set of predefined questions, as given in the example
Logic Chart below. This logic could be modified to take into consideration, other maintenance
constraints, as dictated by a customer, or criteria such as operational environmental restriction.
Using the Logic Tree, a response is made to each question (as given below), following the logic.
This process will lead itself to establish the maintenance strategy and level of repair for each
corrective maintenance task. The questions identify which of the failed units can be removed
from their operational positions with a minimum amount of support resources.
When determining if an item or sub-item should be replaced and/or repaired at 1st line,
consideration must be given to all aspects of the maintenance task. These include fault
diagnostic techniques, accessibility requirements, task verification, elapsed task times,
disruption to the operational environment etc.
Questions for the above ELORA Logic Diagram
Question 1: Is the design of the item such that repair is feasible?
Question 2: Are the item's maintenance characteristics and installation such that a
remove/replace strategy is feasible at first line?
Question 3: Does the item have lower level subassemblies?
Question 4: Does item's maintenance characteristics permit a replacement action of the
sub-item?
Question 5: Does the item's configuration consist of subassemblies from multiple
vendors?
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Except where otherwise noted. All rights reserved. Reproduction in whole or in part without permission is prohibited
Contact email: [email protected]
www.mtain.com
Copyright © - 2001-2011: MTain
Except where otherwise noted. All rights reserved. Reproduction in whole or in part without permission is prohibited
Contact email: [email protected]
Economical Level Of Repair Analysis (ELORA)
Following the LORA, the ELORA provides a recommended repair strategy based upon economic
rational. Consideration is also given to an item's maintainability and physical characteristics.
There are many ELORA models available that can be used for simple and complex applications.
For example MIL-STD-1390 contains several model such as an Avionics Model. In the case of
this model it focuses on the following six major cost drivers:
Inventory cost - includes inventory administration cost, attrition cost, transportation,
etc.
Support Equipment (SE) - the cost of providing the necessary SE (other than standard
tools and SE) for completing a particular CM task at a given level of maintenance.
Space - required for inventory.
Labor cost - the associated cost for personnel to complete each repair task.
Training cost - the cost for upgrading and providing the necessary training to personnel
performing a maintenance task at a given maintenance site and/ or shop.
Documentation - the cost for developing the required documentation for each of the
maintenance options.
These algorithms require specific input data for the system inherent supportability
characteristics and its intended "Use" or deployment profile. System level data includes the
system's expected operational life, operational profile, and site data (distances between
operational centers and repair shop, including the total number of these facilities.). The item
data includes Mean Time Between Failures (MTBF), cost, repair time, procurement lead times
etc. It is these data elements provide the life-cycle cost data and system data used for the
ELORAs.