• Single Channel Speed Trim Fault:

  If a single channel failure occurred, there is no annunciation until you push the System Status Annunciator panel assembly (recall). When you push the annunciator panel, these annunciations show:

  
  *Speed Trim Light Illuminated.
  *System Status Annunicator (6-Pack) "FLT CONT" illuminated.
  *Both Master Caution Lights Illuminated.
  
  

  When you release the annunciator panel assembly, the SPEED TRIM light goes out but the FLT CONT light and Master Caution lights stay on. Push either the left or right Master Caution light (reset) to reset all the annunciations.

  
  Single Channel Speed Trim Fail Possible Causes:

  Before replacing any component perform BITE if available. Go to DFCS/Fault Review/Current Status/Channal A&B/Speed Trim.

  
  

  1.Flight Control Computer (FCC)

  
  Notes:

  The single channel speed trim fault may reset and clear when DFCS Current Status Speed Trim BITE is run.

• Dual Channel Speed Trim Fault:

  If dual channel failure occurred, these annunciations show:

  
  *Speed Trim Light Illuminated
  *System Status Annunicator (6-Pack) "FLT CONT" illuminated.
  *Both Master Caution Lights Illuminated.
  
  Dual Channel Speed Trim Fail Possible Causes:

  Before replacing any component perform BITE if available. Go to DFCS/Fault Review/Current Status/Channal A&B/Speed Trim.

  
  

  1.Stab Trim Electric Motor

  
  

  2.Stab Trim Relay (R384)

  
  

  3.Column Switching Module

  
  

  4.A/P Trim Cutout Switch (S149)

  
  

  5.Flight Control Panel

  
  

  6.Wiring

  
  

  7.Flight Control Computer (FCC)

  
  Flight Contol Panel:

  

  
  

  

  
  Circuit Breakers:

  AFCS SYS A FCC (DC): P18-1 = D2.

  AFCS SYS B FCC (DC): P6-2 = B3.

  
  
  Applicable deferrals 22-10=Speed Trim System (Single Channel Only).
  22-9=Speed Trim Fail Light System.

Training Only