• Heading Flag (HDG): Notes:

  Before trouble shooting a HDG flag, make sure the IRU’s are in NAV mode, the fault lights on the MSU are not illuminated, and status codes 02, 05 or 06 are not displayed on the ISDU. If the fault light is on and/or any of these codes are indicated, replace the IRU or DAA’s first.

  
  HDG Flag-in-view:

  1.Move compass XFR switch on P5 overhead panel to "Both on 1" or "Both on 2" (Depending on the indicator that is flagged).
  
  2.If the HDG flag pulls when XFR switch is moved to the secondary compass source then replace the DAA that normally feeds the indicator.
  
  3.If the HDG flag stays in view when the XFR switch is moved to the secondary source then replace the indicator.
  
  4.If the DAA or indicator does not fix the problem check wiring between them.

  
  More Notes:

  The DAA that normally feeds heading information to the respective HSI’s also sends data to the opposite RDDMI on the majority of -300/500’s. Check your specific prints for on-side or off-side configuration.

  
  ADI INFORMATION:

  

  
  Circuit Breakers:

  F/O XFMR (ALT): P18-2 = B4.

  Capt cmps xfmr (ALT): P6-1 = B12.

  Instrument Transformer 2: P6-1 = A12.

  Instrument Transformer 1: P18-2 = A1.

  DAA IRS #1 DC: P18-2 = D3.

  DAA IRS #1 AC: P18-2 = D2.

  DAA IRS #2 DC: P6-1 = D10.

  DAA IRS #2 AC: P6-1 = D9.

  
  
  More Notes:

  The DAA has separate synchro outputs to each indicator. The output can fail to the HSI for instance, and not the RDDMI. This is typical. If the DAA fails in such a way that both indicators are affected, then you most likely will have a DAA fault code on the ISDU.

  
  Applicable deferrals None.

Training Only