TM  55-1510-221-10 altimeter,  and  supplies  altitude  information  to  the transponder. 2-84.  VERTICAL  VELOCITY  INDICATORS. Vertical  velocity  indicators  are  installed  sepa- rately  on  the  pilot  and  copilot  sides  of  the  instru- ment   panel   (fig.   2-29).   They   indicate   the   speed   at which   the   aircraft   ascends   or   descends   based   on changes  in  atmospheric  pressure.  The  indicator  is  a direct  reading  pressure  instrument  requiring  no  elec- trical  power  for  operation. 2-85.   ACCELEROMETER. The   accelerometer,   located   on   the   instrument panel  registers  and  records  positive  and  negative  G loads  imposed  on  the  aircraft.  One  hand  moves  in the  direction  of  the  G  load  being  applied  while  the other  two,  one  for  positive  G  loads  and  one  for  neg- ative   G   loads,   follow   the   indicating   pointer   to   its maximum   travel.   The   recording   pointers   remain   at the  respective  maximum  travel  positions  of  the  G’s being  applied,  providing  a  record  of  maximum  G loads  encountered.  Depressing  the  push-to-reset knob  at  the  lower  left  comer  of  the  instrument allows  the  recording  pointers  to  return  to  the  normal position. 2-86.   OUTSIDE   AIR   TEMPERATURE   (OAT) GAGE. The  outside  air  temperature  gage,  mounted  out- board  of  the  pilot’s  seat,  (fig.  2-8),  indicates  the  out- side  air  temperature  in  degrees  Celsius. 2-87.   STANDBY   MAGNETIC   COMPASS. W A R N I N G Inaccurate   indications   on   the   standby magnetic  compass  will  occur  while  wind- shield   heat   and/or   air   conditioning   is being  used. The  standby  magnetic  compass  is  located  below the  overhead  fuel  management  panel  and  to  the right   of   the   windshield   divider.   It   may   be   used   in the  event  of  failure  of  the  compass  system,  or  for instrument   cross   check.   Readings   should   be   taken only   during   level   flight   since   errors   may   be   intro- duced  by  turning  or  acceleration.  A  compass  correc- tion   chart   indicating   deviation   is   located   on   the magnetic   compass. 2-88.   MISCELLANEOUS   INSTRUMENTS. a.   Annunciator   Panels.   Three   annunciator panels  are  installed.  One  is  a  warning  panel  with  red fault  identification  lights,  and  the  others  are  caution/ advisory  panels  with  yellow  and  green  identification lights.  The  warning  panel  is  mounted  near  the  center of   the   instrument   panel   below   the   glareshield   (fig. 2-29)  and  one  caution/advisory  panel  is  located  on the  center  subpanel  (fig.  2-6).  The  mission  annuncia- tor  panel  is  located  on  the  copilot’s  sidewall.  Some normal   flight   operations   involve   indications   from the   mission   control   panel   (fig.   4-l).   Illumination   of a  red  warning  light  signifies  the  existence  of  a  haz- ardous  condition  requiring  immediate  corrective NOMENCLATURE COLOR CAUSE  FOR  ILLUMINATION NO.1  FUEL  PRESS RED Fuel  pressure  failure  on  left  side NO.2  FUEL  PRESS RED Fuel  pressure  failure  on  right  side L  BL  AIR  FAIL RED Left  bleed  air  warning  line  has  melted  or  failed,  indicating possible  loss  of  No.1  engine  bleed  air R  BL  AIR  FAIL RED Right  bleed  air  warning  line  has  melted  or  failed,  indicating possible  loss  of  No.  2  engine  bleed  air ALT  WARN RED Cabin  altitude  exceeds  12,500  feet INST  AC RED No  AC  power  to  engine  instruments AP  TRIM  FAIL RED Trim   inoperative   or   running   opposite   direction   commanded NO.1  CHIP  DETR RED Contamination   of   No.1   engine   oil   detected NO.2  CHIP  DETR RED Contamination   of   No.2   engine   oil   detected AP  DISC RED Autopilot  has  disengaged. action. Table  2-6.  Warning  Annunciator  Panel  Legend WARNING  ANNUNCIATOR 2-74