TM 1-1510-225-10 8A-2 8A-10.  USE OF CHECKLIST. Although a good working knowledge of all aircraft procedures  is  desirable,  it  is  not  mandatory  that  they be committed to memory.  The pilot is responsible for the   initiation   and   accomplishment   of   all   required checks.    Checklist  items  will  be  called  out  orally  and the action verified using the checklist (-CL).  Normally, the  Pilot  Not  Flying  (PNF)  will  read  the  checklist  and perform  such  duties  as  directed  by  the  Pilot  Flying (PF).    "As  required"  will  not  be  used  as  a  response; instead the actual position or setting of the unit or item, such  as  "On"  or  "Up"  or  "Approach"  will  be  stated. Upon  completion  of  each  checklist,  the  crewmember reading     the     checklist     will     announce,     "Checklist complete." 8A-11.  CHECKS. a.  Listed  below  are  the   symbols   used   in   the following procedures and their associated meanings. N Indicates performance of step is mandatory for night flights. I Indicates a mandatory check for instrument flights. O Indicates if installed. H Indicates an operational check contained in the performance  section  of  the  condensed checklist. * Indicates performance of step is mandatory for all through flights.  The asterisk applies only to checks performed prior to takeoff. b.  Placarded  items  such  as  switch  and  control positions appear in boldface capital letters. 8A-12.  BEFORE EXTERIOR CHECK. * 1.  Forms/Publications  –  Check  DA  Forms  2408 -12, -13, -14, and -18, DD Form 365-4, locally required forms and publications, and availability   of   operator's   manual   (-10)   and checklist (-CL). H 2.  Oxygen   system   –   Check.      Refer   to   Table 8A-1. a.  Passenger manual drop-out – Push off. b.  Oxygen system – Crew ready. c.   Crew masks – 100%; check operation and stow. NOTE 1850  psi  at  15°  is  a  fully  charged  bottle. Read duration directly from Table 8A-1. (1)  Read oxygen pressure from the gauge. (2)  Read the OAT (with battery on). (3)  Determine     the     percent     of     usable capacity  from  Figure  8A-1  (e.g.,  1100 psi at 0°C = 57%). (4)  Compute     the     oxygen     duration     in minutes from Table 8A-1 by multiplying the full bottle duration by the percent of usable   capacity,   as   in   the   following example: NOTE For  oxygen  duration  computations,  count each  diluter-demand  crew  mask  in  use  as two (e.g., with four passengers and a crew of   two,   enter   the   table   at   eight   people using). (a)  Pilot and copilot with masks set  at 100%   plus   6   passengers   =   10 people using oxygen. (b)  Cylinder volume =115 cubic feet. (c)   Duration with full bottle = 73 minutes. (d)  Duration with 0.57% capacity:  0.57 x 73 = 41 minutes. * 3.  Flight controls – Unlock/check. * 4.  Parking brake – As required. 5.  Manual trim – Check and set to zero. * 6.  LDG GEAR CONTROL – DN. a.  Manual   gear   extension   handle   –   Down and latched. O  * 7.  EFIS POWER – OFF. H 8.  Fuel pumps/crossfeed operation – Check. a.  Fuel  FIREWALL  SHUTOFF  VALVES  – CLOSED. b.  STANDBY PUMPS – ON. c.   BATT   switch   –   ON   (L   and   R   FUEL PRESS,     L     and     R     ENG     ANTI-ICE annunciators illuminated). d.  L  and  R  FUEL  PRESS  annunciators  – Illuminated.