TM 5-4220-231-14&P NOTE Indications are that the Primaryregulator has failed, either closed or  open.     As  air  is  breathed by  divers   the   pressure will naturally    fall. b. EP-2 Primary    Air  Supply    is  contaminated: (1)    Close   DACC  HP  IN PRIMARY   (AHP-V405). (2)    Open    DACC  HP  IN SECONDARY    (AHP-V401). (3)    Remove    protective     cap   corresponding to  ALP-V508. (4)    Open    BLEED  VALVE  (ALP-V508)    on  VTA Control   Panel.    Ventilate Volume    Tank   for  1  minute. WARNING During     ventilation, do    not   allow    the    VTA  SUPPLY PRESSURE Gage (ALP-G510) to    drop below set over-bottom pressure. Failure to  observe this   warning could    cause death to  personnel. (5) Close BLEED   VALVE  (ALP-V508). Allow  Volume   Tank   to  fill.   Repeat steps (4)  and    (5)  one   time,   so   that   Volume    Tank   is  vented twice. Replace cap. (6)  Notify   divers to  ventilate helmets. (7)  Abort   dive. Recover divers. c. EP-3 Sudden drop   in  pressure on   VTA  SUPPLY PRESSURE Gage (ALP-G51 0): (1) Close    DACC   HP  IN  PRIMARY   (AHP-V405). (2) Open    DACC   HP  IN SECONDARY (AHP-V401). (7) Abort  dive. Recover divers. NOTE Indications are that    the Primary regulator has failed closed or possibly that   the   interconnecting hose from   the   DACC   to   the   VTA has    ruptured. As   air   is  breathed down    by   divers the   pressure will naturally fall.   Comparison should be  made with  DACC   CONSOLE PRESSURE gage ALP-G423. Change 6 2-81