Fault Message:

IRU/HUDC CONS FAULT

Fault Code:

343001EHUD

Associated CAS:

HUD MISCOMPARE
(Caution)

Head-Up Display System (HUD) does not receive data from the Inertial Reference Unit (IRU).

• Head-Up Flight Display Computer (HFDC) (A250)
• Inertial Reference Unit (IRU) 1 (A32)
• Inertial Reference Unit (IRU) 2 (A33)
• Inertial Reference Unit (IRU) 3 (A34)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

If more fault reports are sent by a different system about the same IRU, do the Operational Test of the Inertial Reference Units (IRU)

1. Perform wiring check between IRU 1, JB5 and HUDC as follow:

   From	To	Result
   A32BP1-E5	A250BP1-F1
   A32BP1-E6	A250BP1-G1
   GND	A250BP1- D2
   A32BP1-SH	A250BP1-SH

   1. If wiring checks are not good, repair defective wiring as required and do close out.
   2. If wiring checks are good, continue with next step.
      NOTE: When short circuit is detected, remove all interface components and reinstall one at a time to isolate short.

2. Perform wiring check between IRU 2, JB6 and HUDC as follows:

   From	To	Result
   A33BP1-E5	A250EP1-J1
   A33BP1-E6	A250EP1-J2
   GND	A250EP1-H2
   A33BP1-SH	A250EP1-SH

   1. If wiring checks are not good, repair defective wiring as required and do close out.
   2. If wiring checks are good, continue with next step.
      NOTE: When short circuit is detected, remove all interface components and reinstall one at a time to isolate short (interface component includes Satellite Receiver Transceiver SRT).

3. Perform wiring check between IRU 3, JB5 and HUDC as follows:

   From	To	Result
   A34BP1-E5	A250BP1-A1
   A34BP1-E6	A250BP1-A2
   GND	A250BP1- B2
   A34BP1-SH	A250BP1-SH
   A34BP1-G7	A250EP1-C1
   A34BP1-G8	A250EP1-C2
   GND	A250EP1- B2
   A34BP1-SH	A250EP1-SH

   1. If wiring checks are not good, repair defective wiring as required and do close out.
   2. If wiring checks are good, continue with next step.

4. Replace defective IRU(s).

   1. If system checks are good, do close out.
   2. If fault remains, continue with next step.

5. Replace HUDC.
6. Do close out.