receptacle  for  free  water.  If  free  water  is  seen, decontaminate  the  system  according  to  applicable procedures. Contamination  Analysis Normally,  contamination  analysis  of  SE  fluid samples is accomplished by using the contamination analysis   kit. You  may  use  other  approved measurement  methods,  if  available  or  if  required. Decontamination   of   unacceptable   equipments   is performed   by   recirculation   cleaning,   purifying, flushing, or purging, as required; these actions are performed  by  the  supporting  activity. Recirculation  Cleaning Recirculation  cleaning  is  used  when  equipment  is unacceptably contaminated with particulate matter (in excess  of  Navy  Standard  Class  3),  but  the  fluid  is otherwise  considered  satisfactory.  In  recirculation cleaning,  the  equipment  is  self-cleaned  using  its internal filters, the 3-micron elements in particular. You  begin  by  operating  the  contaminated  SE  so maximum  circulation  of  fluid  through  the  equipment reservoir   and   internal   3-micron   filters   occurs. Maintain the flow long enough to allow a total flow equivalent to at least five times the total fluid capacity of  the  equipment  reservoir. Monitor  all  filter differential-pressure   indicators   throughout   the operation.  If  elements  appear  to  be  loaded,  check  and replace  them. You should resample and analyze the fluid from the reservoir. If  improvement  is  shown,  but  the contamination  level  is  still  excessive,  repeat  the process. If there is still no improvement, try to find the internal contamination source, such as a failed component. Replace any components you determine to   be   contaminating   the   fluid,   and   continue decontamination by draining, flushing, and refilling the equipment with new filtered fluid. Recirculation clean   and   resample,   as   before,   to   determine acceptability. When you find the fluid samples from the  reservoir  to  be  within  acceptable  limits, recirculation cleaning may be terminated. Flushing Flushing  is  used  to  decontaminate  SE  heavily contaminated with particulate matter, or when the fluid contains a substance not readily removed by the internal filters. To begin the flushing procedure, you drain, flush, and reservice the equipment reservoir using new filtered fluid. If contamination originated at  the  pump,  drain  and  flush  the  hoses  and  lines directly associated with the pump output separately. Operate  the  equipment  so  fluid  flows  through  all circuits. Allow output (or return line) fluid to dump overboard into a waste receptacle. Continue flushing until  a  quantity  of  fluid  equal  to  the  equipment reservoir   capacity   has   passed   through   the   unit. Closely  monitor  the  reservoir  level  during  the operation,  adding  new  filtered  fluid,  as  required.  This prevents the reservoir level from dropping below the one-third  full  point, Take a sample and analyze the output and the reservoir  fluids.  If  the  contamination  level  shows improvement  but  is  still  unacceptable,  repeat  the flushing  operation. If  extensive  flushing  fails  to decontaminate  the  equipment,  you  should  request assistance from the supporting engineering activity. Upon  successful  completion  of  system  flushing, recirculation  clean  the  equipment  for  a  minimum period. Then, take a sample from the system to verify the  contamination  level  as  being  acceptable.  When you have done this, service the reservoir. Purging Purging  of  SE  hydraulic  systems  is  performed only upon recommendation from, and under the direct supervision of, the cognizant engineering activity. It is  the  responsibility  of  the  cognizant  engineering activity to select the required cleaning agents, provide detailed  cleaning  procedures,  and  perform  tests  upon completion  of  purging  to  ensure  satisfactory  removal of all cleaning agents.    Whenever possible, purging operations  are  to  be  accomplished  at  a  naval  aviation depot  facility  (NADEP).  Intermediate  maintenance activities   are   not   authorized   to   perform   system purging  without  direct  depot  supervision. 4-40