TM 1-1510-225-10 8-3 b.  Pitot (2), stall warning, and fuel vent heat (2) – Check on, then OFF. 13.  Cabin door annunciator light – Check on. H 14.  Oxygen  system  –  Check.    Refer  to  Table 8-1, Oxygen Duration. 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 8-1. (1)  Read    oxygen    pressure    from    the gauge. (2)  Read the OAT (with battery on). (3)  Determine    the    percent    of    usable capacity  from  Figure  8-1  (e.g.,  1100 psi at 0°C = 57%). (4)  Compute    the    oxygen    duration    in minutes from Table 8-1 by multiplying the full bottle duration by the percent of usable capacity, as in the following example. (a)  Pilot  and  copilot  with  masks  set at 100% plus 6 passengers = 10 people using oxygen. 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). (b)  Cylinder volume =115 cubic feet. (c)   Duration with full bottle = 73 minutes. (d)  Duration with 57% capacity:  .57 x 73 = 41 minutes. 15.  Annunciator lights – Check. 16.  Hydraulic fluid sensor – Check. 17.  Fire detection system – Check. 18.  Fire extinguishers – TEST. 19.  Stall and landing gear warning – Check. 20.  FLAPS – As desired. 21.  ENGINE ANTI-ICE – As desired. 22.  BATT switch – OFF. 23.  EFIS AUX POWER – Test. a.  TEST    switch    –    Hold    to    TEST    for 5 seconds  (green  TEST  annunciator  will illuminate for 5 seconds). b.  TEST switch – Release. 8-13.  FUEL SAMPLE AND OIL CHECK. CAUTION A  cold  oil  check  is  unreliable.    Oil  should be    checked    within    10    minutes    after stopping engine.  If more than 10 minutes have elapsed, motor engine for 40 seconds,  then  recheck.    If  more  than 10 hours   have   elapsed,   run   engine   for 2 minutes,    then    recheck.        Add    oil    as required.  Do not overfill. NOTE Fuel   and    oil    quantity    checks    may    be performed    prior    to    Exterior    Check    to preclude carrying a ladder and fuel sample container    during    the    balance    of    the preflight.  During warm weather, open fuel caps  slowly  to  prevent  being  sprayed  by fuel under pressure. 1.  Fuel  sample  –  Check  collective  fuel  sample from   all   drains   for   possible   contamination. (Refer to Chapter 2 for locations.)