Since  only  the  month  and  year  are  used  in computing   service-life   dates,   the   date   the hermetically sealed container is opened and the expiration date must be computed to the last day of  the  month  involved.  If  the  date  the  sealed container   was   opened   is   not   available,   the installed-life must be computed from the date of manufacture as determined from the lot number. Marking Expiration Dates Before installing a CAD in an aircraft system, both CAD service-life expiration dates (shelf-life and installed-life) should be computed. The time limit that is exceeded first will be the service-life expiration  date  of  the  CAD.  The  service-life expiration  date  must  be  entered  in  the  aircraft logbook. Use  permanent  ink  for  marking  CADs  with container  opened  dates  and  service-life  expiration dates. Do not scribe, scratch, or eletroetch these dates,  as  damage  will  occur  to  the  CAD’s corrosion  resistance  surface.  The  marking  pen, NSN  7520-00-043-3408,  is  available  from  GSA supply,  and  is  recommended  for  this  purpose. When you install a CAD in an aircraft system, a  log  entry  must  be  made  on  OPNAV  Form 4790/26A,  as  directed  by  OPNAVINST  4790.2 (series).   When   a   CAD’s   hermetically   sealed container  is  opened,  the  container  opened  date and  the  service-life  expiration  date  (month  and year) must be marked with indelible ink on the container  and  on  each  CAD  in  the  container. Service-Life   Extension Contingency   service-life   extensions   for   the CADs listed in the NAVAIR 11-100-1 (series), not to   exceed   30   days,   may   be   granted   by   the commanding  officer  or  his  authorized  repre- sentative.  The  extensions  may  be  applied  to  a specific   CAD   on   a   one-time   only   basis   when replacements  are  not  available  and  failure  to extend   the   service-life   would   disrupt   flight operations. The contingency authority is granted on  the  condition  that  Naval  Ordnance  Station, Indian   Head,   Maryland;   NAVAIRSYSCOM, Washington,  D.C.;  and  SPCC,  Mechanicsburg, Pennsylvania,  be  immediately  notified  by  message or speed letter when such authority is exercised. When  the  situation  warrants,  an  additional service-life   extension   beyond   the   30-day contingency   extension   may   be   requested   by message   from   NAVORDSTA.   All   extensions beyond  30  days  must  be  approved  by  the NAVORDSTA   or   NAVAIRSYSCOM.   All   ap- proved  additional  service-life  extensions  will  be transmitted by message to the activity making the request. When a service-life extension is granted, an  entry  must  be  made  in  the  aircraft  logbook. When  an  aircraft  is  transferred  with  a  service-life extension in effect, the gaining activity must be notified,   and   no   new   contingency   service-life extensions  may  be  granted  by  the  commanding officer  of  the  gaining  activity. Service-life  Change The  permanent  service  life  of  a  CAD  maybe changed  only  by  a  rapid  action  change  (RAC), interim  rapid  action  change  (IRAC),  or  formal change to NAVAIR 11-100-1 (series) as directed by  COMNAVAIRSYSCOM,  Washington,  D.C. If the change affects those items installed in an aircraft,  the  change  will  be  recorded  in  the aircraft’s  logbook.  A  line  will  be  drawn  through the  service-life  expiration  date  shown  and  the  new computed   expiration   date   entered,   citing   the authority  for  the  change;  for  example,  message number, rapid action change number, or change number. Each new expiration date will supersede the  previous  date.  The  latest  expiration  date entered in the aircraft logbook will always be the final date the CAD may remain installed in the aircraft. When a contingency service-life extension has been  authorized  for  a  specific  CAD,  the  new computed service-life expiration date (month and year)  will  be  added  to  the  original  aircraft  logbook entry for that CAD. When an additional service- life  extension  has  been  granted  for  a  specific CAD, the new service-life expiration date (month and  year)  will  be  added  to  the  original  aircraft logbook   entry. CAD Maintenance Policy CAD maintenance policy prohibits unauthor- ized maintenance or adjustments to a CAD at any of  the  three  levels  of  maintenance:  organizational, intermediate, or depot. Authorized maintenance actions  are  limited  to  removal,  inspection,  and replacement,  unless  specifically  detailed  in  the aircraft  MIM  or  by  a  technical  directive. CADs  and  items  of  equipment  in  ejection systems  are  for  one-time  use  only.  They  are  never to be refurbished or used again after firing. This is equally true of functional equipment, rigid lines, plumbing  lines,  and  hoses.  Ejection  seats  and escape system components that have been used 1-10