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    Is Life Ratings a different way of saying MTBF? Can an LSA database store 5 different Life Ratings?


    Answer

    I have performed extensive research to find references to “Life Ratings” including:
    ·  review of DoD 5000.01, DoDI 5000.02, and the DAG; 
    ·  accessing MIL-STD-1388-2A/2B for a Data Element Description (DED) on Life Rating;
    ·  review of NAVAIR Instructions and Guidance which might address the definition and application of “Life Rating” for this NAVAIR system/component.
     
    I have even spoken directly with the individual who submitted the question and I have been unsuccessful in finding information on “Life Ratings”.  We did discuss the Contractor’s LSAR tool, SLICWAVE, which I have had personal experience with its predecessor, SLIC III, and told the AAP submitter that as long as the Contractor’s LSAR database is compliant with SAE GEIA –STD-0007, it should be able to store five different predicted “Life Ratings”, or equivalent “Service Life”, “Useful Life” or “End of Life” values.
     
    As far as “Life Ratings” go, the best I can come up with are the terms “Service Life” or “Useful Life”.
     
    Service Life, as defined in the DAU Glossary,quantifies the average or mean life of the item” which is consistent with Mean Time Between Failure (MTBF) at the component level. Service Life often refers to the mean life between overhauls, the mandatory replacement time, or the total usefulness of the item in respect to the weapon it supports; that is, from first inception of the weapon until final phase-out. There is no general formula for the computation of service life.
     
    Here is a helpful quote about “Useable’ (i.e., “Useful”) Life from a related AAP Question about a Usable Life Period for COTS equipment:
     
    “I am not aware of any specific research completed to determine a Usable Life Period for COTS equipment in a general sense. At the following URL you can obtain the DoD Guide to COTS and NDI equipment. 
    http://www.everyspec.com/DoD/DoD+PUBLICATIONS/download.php?spec=SD-2_JAN2010.025068.pdf
     
    You should base your decision on usable life period by finding the answers to the following questions. 
     
    What is the requirement for the equipment?  How long is the forecast need for the equipment?
    What type of equipment are you purchasing (IT, radio, mechanical, tools, personal issue)? 
    What market research data is available? 
    Is this equipment currently available in the commercial market? 
    How long has it been available? 
    What is the technical refresh period for this equipment?  How often does the technology change?
    Is the equipment built with a modular design that easily accommodates upgrades/modifications? 
    Is the commercial product being used in environments/conditions similar to the intended environment/conditions it will experience in government use?
    Does it need to be integrated with other systems?
    What is the support structure for this equipment (number of vendors, financial viability of vendors)?
    What is drove the original development and production of this equipment (other government use, commercial use)?
    What new technologies are being developed relating to your requirement?
     
    Implications for choosing too short a usable life period could be lack of support/sustainment as the system ages.  Also, the cost to support the equipment may increase as it ages and requires continuing maintenance to keep it operating. 
     
    Implications for choosing too long a usable life period are life cycle cost estimates being inaccurate and budgeting for support for after the system is retired.  Also by forecasting a usable life beyond the actual may delay planning and budgeting to replace an aging piece of equipment.
     
    Two additional references which may be of help include the “Military Equipment Useful Life Study”
    http://www.acq.osd.mil/pepolicy/pdfs/OPTEMPO/OPTEMPO Phase II Final Report.pdf and the 2016-2017 and the 2016-2017 NAVAIR Acquisition Guide http://www.navair.navy.mil/nawctsd/Resources/Library/Acqguide/2016-2017-NAG.pdf 

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