adding,   deleting,   or   changing   steps   in   the   work sequence. Addendums Depending on the complexity of the task, it may be desirable to have two or more work centers working portions of the task concurrently. If so, Planning and Estimating  (P&E)  will  initiate  an  addendum  to  the original  CWP.  The  addendum  will  include  all  the headings of the CWP-references, material list, safety requirements,  work  sequence,  and  so  forth.  When  you complete the work steps, include the addendum(s) with the  CWP. LEVELS OF ESSENTIALITY, ASSURANCE, AND CONTROL To  provide  your  customers  both  repair  quality  and quality  assurance,  you  as  a  supervisor  and  your maintenance  personnel  must  understand  and  appreciate them  and  their  operational  environment.  This  will require that you and your personnel give serious thought and consideration to how a system’s nonperformance may endanger personnel safety and threaten the ship’s mission capability. For example, you are not going to be aboard the submarine as it does its deep dive to test hull integrity (and your hull packing work). You must stress to your workers how system essentiality, in an operation environment,  equates  with  mission  capability  and personnel  safety.  In  other  words,  workers  must understand how the work they perform in a maintenance or   repair   environment   can   seriously   affect   the operational capabilities of the tended unit as well as the safety of the personnel aboard the unit. This is where the assigned  levels  of  essentiality,  assurance,  and  control come into play. What do we mean by these terms? We will discuss each in the following paragraphs. LEVELS  OF  ESSENTIALITY A number of early failures in certain submarine and surface ship systems were traced to use of the wrong material. This led to a system for prevention involving levels of essentiality. A level of essentiality is simply a range of controls in two broad categories representing a certain  high  degree  of  confidence  that  procurement specifications have been met. These categories are 1.  verification  of  material,  and 2.  confirmation  of  satisfactory  completion  of  tests and  inspections  required  by  the  ordering  data. Levels of essentiality are codes, assigned by the ship according to the QA manual, that indicate the degree to which the ship’s system, subsystem, or components are necessary or indispensable in the performance of the ship’s  mission.  Levels  of  essentiality  also  indicate  the impact that catastrophic failure of the associated part or equipment would have on the ship’s mission capability and  personnel  safety. LEVELS OF ASSURANCE Quality assurance is divided into three levels: A, B, C.  Each  level  reflects  certain  quality  verification requirements of individual fabrication in process or repair items. Here, verification refers to the total of quality  of  controls,  tests  and  inspections.  Level  A assurance provides the most stringent or restrictive verification techniques. This normally requires both quality controls and test or inspection methods.  Level B assurance  provides  adequate  verification  techniques. This normally requires limited quality controls and may or  may  not  require  tests  or  inspections.  Level   C assurance  provides  minimum  or  “as  necessary” verification  techniques.  his  normally  requires  very little  quality  control  or  tests  or  inspections. LEVELS OF CONTROL Quality  control  may  also  be  assigned  generally  to any of the three levels–A, B, or C. Levels of control are the  degrees  of  control  measures  required  to  assure reliability of repairs made to a system, subsystem, or component. Furthermore, levels of control (quality control techniques) are the means by which we achieve levels of assurance. An additional category, which you will see when you work on periscopes, is Level I. This is reserved for systems that require  maximum confidence  that the composition of installed material is correct. CONTROLLED MATERIAL Some material, as part of a product destined for fleet use,  has  to  be  systematically  controlled  from procurement   through   receipt,   stowage,   issue, fabrication, repair, and installation to ensure both quality and material traceability. Controlled material is any material you use that must be accounted for (controlled) and  identified  throughout  the  manufacturing  and  repair process,   including   installation,   to   meet   the specifications  required  of  the  end  product.  Controlled material must be inspected by your CMPO for required attributes before you can use it in a system or component 6-10