Stracener_EMIS 7305/5305_Spr08_04.15.08 Level-of-Repair Analysis (LORA) Dr. Jerrell T. Stracener, SAE Fellow Leadership in Engineering EMIS 7305/5305 Systems

Stracener_EMIS 7305/5305_Spr08_04.15.08

Level-of-Repair Analysis (LORA)

Dr. Jerrell T. Stracener, SAE Fellow

Leadership in Engineering

EMIS 7305/5305Systems Reliability, Supportability and Availability Analysis

Systems Engineering ProgramDepartment of Engineering Management, Information and Systems


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What is The Level Of Repair Analysis (LORA)?

• Objective To develop an optimized maintenance philosophy based upon

a cost rational.

• Purpose To establish the least cost level of repair or discard for

maintenance actions and to influence the equipment design.


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Level of Repair Analysis Process

• based on: - non-economic analysis- economic analysis- readiness objectives

• Process steps :1. Identify Level of Repair Analysis candidates. 2. Identify constraints. 3. Perform non-economic LORA evaluations.4. Perform economic LORA evaluations. 5. Conduct sensitivity analysis.


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Identify Level of Repair Analysis candidates

• LORA process is primarily applied to corrective maintenance actions after the Failure Modes and Effects Criticality Analysis (FMECA) has been performed.

• Preventive and corrective maintenance actions are analyzed separately.

MaintenanceCandidate List

Failure Modesand Effects

Criticality Analysis

CorrectiveMaintenance List

RepairAnalysis

PreventativeMaintenance

Candidate List

ReliabilityCentered

Maintenance

MaintenanceData

• Preventive maintenance decisions are usually handled by the Reliability Centered Maintenance (RCM) process.


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Identify Level of Repair Analysis candidates

Level of Repair analysis candidates must meet the following requirements:

• Level of Repair analysis candidates must be “maintenance significant items." Maintenance significant items affect the system if they fail. i.e, item failure causes some degradation of the mission capability of the system.

• LORA candidates must be “repairable.” - An item is repaired when a lower level component or assembly is removed and

replaced to bring the item back to ready-for-issue condition.- Repair parts are not repair analysis candidates because they are not repairable

by this definition. - cost of repair parts is considered when the repair cost of a candidate is

calculated. • LORA candidates must also include some supportability requirements (spares,

support equipment, manpower, documentation, or facilities) in the cost of the repair action.- the item must fail often enough or require a sufficient investment of repair

resources to make it worthwhile to plan for its failure, i.e, there must be some cost to performing maintenance on the item.


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Identify constraints

The Level of repair analysis process may be constrained by the operating environment and by cost and support resources. Such constraints include:

• Operational use and mission requirements

• Program specific cost and schedule constraints

• Non-economic preemptive factors like safety factors, policy decisions, repair feasibility, special handling factors, human factors and other non-cost based decision criteria


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Perform Non-Economic Repair analysis Evaluation

A Level of repair analysis includes an economic and a non-economic analysis - the non-economic analysis should be done first and can

preempt items from the economic analysis- cost is not considered in a non-economic analysis- non-economic factors include, but are not limited to, the

following:

Safety. Constraints on the existing logistics support structure Technical feasibility of repair Mission success (criticality and effectiveness) Security Human factors Policy (specifications and regulations pertaining to items)


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Non-Economic LORA

• This method provides a means of examining the factors that determine the maintenance level for repair analysis candidates. The purpose of the non-economic analysis is to avoid the time and expense of an economic analysis

• A non-economic LORA addresses the pre-empting factors that override cost considerations or existing repair analysis decisions on similar systems. A pre-empting factor is a restraint, stipulation, or special requirement that forces the repair or discard decision to a specific maintenance level or limits the support alternatives available


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Non-Economic LORA Continued

• It determines the maintenance level where repair or discard will be performed

- evaluation is performed without consideration of cost

- recommendations or conclusions based upon this evaluation may include an economic analysis that assigns a value to the non-economic decisions


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Non-Economic LORA

• Sequence of questions

The non-economic LORA is a logical sequence of questions concerning factors that affect the level at which repair or discard can be performed.

- questions in the following non- economic analysis table should be asked of each item on the repair analysis candidate list

- response—“yes” or “no”—reflects the maintenance level where repair or discard decisions are restricted and the reason for the restriction

- analyst determines a preliminary maintenance concept based on the “yes” responses

- “No” responses should be determined, but need not be reported


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Non-Economic Factor Yes No Maintenance Level Affected or Restricted

Reason for Restriction

Safety:Do hazardous conditions preclude the item from being repaired at any specified maintenance level?Conditions to be considered include, but are not limited to: High Voltage Radiation Temperature Extremes Chemicals for Toxic Gases Excessive Noise Explosives Excessive Weight Other: 1. 2.Security:Do security conditions preclude the item from being repaired at a specific maintenance level?Policy/existing maintenance concepts:Do existing specifications, standards, or regulations pertain to the level of maintenance at which a particular item can or cannot be repaired?(This category includes existing maintenance concepts or policies on similar systems to be used as a baseline for comparison.)

Non-Economic Level of Repair analysis


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Non-Economic Factor (continued) Yes No Maintenance Level Affected or Restricted


Warranties:Are there warranties on any item in the repair analysis candidate list which restrict the maintenance level for repair or discard?Does the warranty eliminate organic support of an item?Readiness/Mission Success:Will mission readiness be compromised if any item is repaired or discarded at a specific maintenance level?Transportation/Transportability:Are there any transportation factors which might preclude the transfer of systems from the user to the maintenance activity for repair? The factors include: weightsizevolumespecial handling requirementssusceptibility to damageother:Support Equipment & Test Measurement & Diagnostic Equipment (TMDE):Are special tools/test equipment required which would force repair to be performed at a special level of maintenance.Does the item require calibration which mandates performance of maintenance at certain levels due to system sensitivity or lack of calibration equipment at a level?



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TMDE continued:Does availability, mobility, size or weight of SE and TMDE restrict the maintenance levels? (* see footnote)Packaging, Handling, and Storage:Does the item’s size, weight, or volume, impose restrictions on storage? This may restrict the level where items/parts can be stocked. (This would include storage of support equipment and TMDE.)Are there special PH&S requirements? (i.e., packaging of computer hardware/software, hazardous material, fragile material, climate control, and packaging of materials susceptible to damage during transportation).Manpower and Personnel:Are an adequate number of skilled personnel available to perform repair at a specified maintenance level?Would repair or discard at a level create a problem with the existing workload?Facilities:Special/unique facility requirements:clean roomssize of test equipmentclimate controlcorrosion controlforging/casting/stampingsophisticated calibration equipmentnuclear hardness requirements


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Facilities, continued:Special Procedures for Repair:hermetically sealed unitsexcessive repair timesmagnetic particle inspectionx-ray inspectionTesting Procedures:vibration/shock analysiswind tunnel testingalignment Other Factors (if applicable):



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Perform Economic LORA Evaluation (ELORA)

Economic Level of Repair Analysis studies various supportability and cost factors to determine the best level of repair or discard for the items under consideration.

Level of Repair Analysis model :

Joint Aviation Model for Level Of Repair Analysis

• This model is used by NAVAIR to perform all repair analyses for NAVAIR programs. It may be used for joint programs or by other services as required.


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• The JAM for LOR A is designed to determine the best and most economical maintenance level for corrective maintenance items. - main purpose of this model is to provide a “rational

basis” for making the repair level decisions that go into a maintenance plan

- usually performed early in Engineering Manufacturing Development (EMD)

- provides recommendations on how to fashion a maintenance plan for a system


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• The model calculates the cost of several “standard” maintenance alternatives and estimates the “optimal” maintenance alternative for each input.

• “LORA Life Cycle Cost” of these alternatives and the model’s “Sensitivity Analysis” can be used to perform “regression” analyses to predict when changes in the optimal maintenance alternative will occur.


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• JAM for LORA may be used for studies to determine:

The minimum required “MTBF” to make an item economically “depot” repair

The number of pieces of “support equipment” required for each repair site

The difference in LORA life cycle cost of using an alternative other than the “optimal” LORA alternative

The cost of a “user determined maintenance alternative.” The cost difference, over the life cycle of the equipment,

if the “MTBF” or some other important parameter changes significantly


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JAM for LORA uses logistics parameters to estimate the differences in life cycle cost between various maintenance alternatives. The user enters data that describes:

The “sites” where the “items” will be repaired The interrelationship of the “repair sites” The “items” being studied The “item hierarchy” The characteristics of the “items” And the “support equipment,” “documentation,”

“facilities,” and “training” required to perform the assigned maintenance tasks


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The model uses this data to determine the number of failures for each item at each site, the quantity and cost of support equipment required at each site, and the number of spares required at each site over the life cycle for each maintenance alternatives by calculating: The number of failures, removals, scraps and discards

that occur at each site The of number of pieces of “support equipment” required

for each site The cost for inventory, labor, material, transportation and

facility space at each site And the number of replacement spares required for each

site


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Conduct Sensitivity Analysis

After an economic analysis has been performed and a maintenance concept has been selected, a sensitivity analysis is conducted.

- allows the program office to study the impact that changing various input parameters has on the maintenance concept

- used to assess how non-economic factors impact life cycle costs


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Influence of LORA Results on Other Logistics Processes

• LORA results can influence the maintenance philosophy, the logistics support cost, the total life cycle cost of ownership, and the operational readiness of the hardware system. In order to influence design

- recommendations should be made when the equipment’s preliminary design has been determined

- should be updated as required throughout the life of the system


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Influence of LORA Results on Other Logistics Processes

• LORA process interfaces with maintenance planning, reliability, and Source Maintenance and Recoverability (SMR) coding in the following ways:

Maintenance planning— LORA process identifies the maintenance level and logistics support costs

Reliability— LORA process can be used to determine if changes in the reliability of critical items will effect the maintenance decision

Recoverability coding— LORA process should be used as a basis for the maintenance portion of the SMR code by identifying - source of the item- the maintenance levels that repair and replace the item- levels that condemn and recover the item


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Example: Motor Repair/Replacement decisions flow chart


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Example: Five level of Motor Repair

Level 1 repair is a basic overhaul or reconditioning. It includes cleaning components, replacing bearings, and replenishing lubricants. It also includes inspection and testing during the incoming stage, the repair process, and during final testing.

Level 2 repairs include everything in Level 1, but add stator winding, varnish-resin treatment, worn bearing fit repair, and shaft straightening

Level 3 adds stator rewinding; that is, replacing the windings and insulation system. Smaller motors with two or four poles are relatively simple to rewind. Special windings such as two-speed, or very low-speed windings, can add considerable time and material to a repair


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Level 4 is the most comprehensive repair level; it encompasses all of

the previous levels, and adds major lamination repair and/ or rotor rebar.

- may include restacking or replacing the stator laminations, and shaft replacement

- before taking on major repairs at this level, first consider the motor replacement option. Not only will the cost of repair be high at Level 4, but the uncertainty associated with the size of the repair compounds the risk of successfully completing the job


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Level 5 repairs apply to motors that normally would be replaced except for special circumstances, such as the unavailability of a spare or replacement unit. - could apply to any of the circumstances at the other four levels

of repair - includes misapplied motors and vintage pre U-frame motors

Note: There is no simple ratio exists between the factors of repairs and costs. By recognizing that there are five levels of repairs, decision makers will understand that considering only the cost of a motor repair versus replacement can be too simplistic to yield an accurate assessment.


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References :

• NAVAIR Contracting for Supportability Guide

http://logistics.navair.navy.mil/cfsg/index.cfm• MTain Engineering services Homepage on the Internet

http://www.mtain.com/logistics/loglora.htm• Energy Efficiency and Renewable Energy

US department of energy.

http://www.eere.energy.gov

Documents

Stracener_EMIS 7305/5305_Spr08_04.15.08 Level-of-Repair Analysis (LORA) Dr. Jerrell T. Stracener, SAE Fellow Leadership in Engineering EMIS 7305/5305 Systems