TM 1-1510-225-10 3C-11 information  for  at  least  30  minutes  after  a  total  failure of the aircraft electrical system. The   power   supply   contains   sealed   lead-acid batteries  with  a  rating  of  5.0  ampere  hours.    During normal operation, the aircraft 28 Vdc system supplies power  to  the  indicator  and  power  supply  batteries.  In the   event   aircraft   electrical   power   fails,   the   power supply will take over the duties of powering the attitude indicator. The   attitude   indicator   is   a   28   Vdc   powered, electrically driven gyro and contains an inverter circuit board  for  converting  the  28  Vdc  input  to  22 Vac 400 Hz  for  indicator  operation.    The  power  warning  flag  is rotated out of sight by a flag motor that allows the flag to    display    if    one    or    more    phases    of    power    are interrupted.    The  flag  motor  also  allows  the  flag  to display if the   PULL  TO  CAGE  knob  is  in  the  caged position.  The rotor speed and the mechanical erection system enable the indicator to provide a minimum of 9 minutes  of  useful  attitude  information  after  complete electrical power interruption. (2)   ANG   .   The   standby   attitude   i ndicator, located    on    the    extreme    left    center    of    the    pilot's instrument panel, is powered by engine bleed air and provides a visual reference of the aircraft pitch and roll.   The attitude indicator is comprised of a self contained gyro to erect the sphere which provides the pitch and roll  reference,  an  indicating  symbol  which  represents the aircraft, and a horizontal line behind the indicating symbol  which  represents  the  horizon.    The  moveable indicating symbol may be adjusted vertically to correct for  variations  in  level  flight  attitudes  by  a  small  knob located on the front base of the indicator. b.    Controls, Indicators, and Functions.  (1)   A    three-position    switch    and    a    three- legend  annunciator  unit,  located  below  the  indicator, provide  system  control,  test,  and  visual  indication  of the system status.  The three-position switch (normally OFF), placarded  ON  /  OFF  /  TEST,  provides  control and  test  capabilities  of  the  battery  powered  system.   While   in   the   normal   OFF   position,   the   annunciator placarded, AUX ARM, will be illuminated indicating the system  batteries  are  being  maintained  in  a  charged condition and the system is in a standby (non-active) mode.  Placing in the TEST  position activates a check of  the  battery  pack  and  illuminates  the    AUX  TEST annunciator.  Placing in the  ON position activates the Standby Horizon Indicator system and illuminates the AUX   ON   annunciator   (provided   the   system   circuit breaker is set). (2)   Standby     Attitude     Reference     Indicator Functions  OSA  .  Refer to Figure 3C-5. 1.  Roll Pointer 2.  Horizon Line 3.  Caging/Pitch-Trim Knob 4.  Trim Pointer 5.  Pitch-Trim Scale 6.  Miniature Aircraft 7.  Drum 8.  Power Warning Flag 9.  Roll Index Figure 3C-5.  Standby Attitude Reference Indicator  OSA (a)  Roll Pointer – Indicates vertical in any roll attitude. (b)  Horizon     Line     –     Indicates     earth's horizon relative to aircraft pitch attitude. (c)  Caging / Pitch-Trim Knob – Pulled to cage the indicator and rotated to adjust the miniature aircraft attitude. (d)  Trim Pointer – Indicates trim displacement. (e)  Pitch-Trim Scale – Measures displacement of miniature aircraft. (f)   Miniature Aircraft – Represents aircraft   nose   and   wings.      Indicates   roll   and   pitch attitude   relative   to   the   horizon.      Adjustable   through pitch trim knob for varying pitch attitudes. (g)  Drum   –   Directly   linked   to   the   spin motor to provide direct reading of aircraft movement in roll and pitch.  Marked each 5 in pitch.  Black area of drum  indicates  dive  and  blue  or  gray  area  indicates climb.