Fault Message:

RA1/WRG/HUDC COM FAULT

Fault Code:

343000EHUD

Associated CAS:

None

Head-Up-Display (HUD) System does not receive the altitude signal from the Radio Altimeter (RA) 1 System (RAD 1 off/fail, out of range, interface malfunction).

• Head-Up Flight Display Computer (HFDC) (A250)
• Radio Altimeter (RA) Unit 1 (A67)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

• Before proceeding with troubleshooting, remember that while on ground radio altitude displayed values may be affected by the ground surface material or surrounding equipment near the antennas. If the condition is only present on ground, the aircraft may me moved to another location to monitor the effect
• The radio altimeter (RA) supplies altitude signals to other systems. When one of these signals does not show, the smart LRU will send a fault (CAIMS) report about the RA. You can get access to the active faults on the CAIMS PMAT to find the fault messages and the fault isolation procedure. If there are more than one CAIMS fault message reported by the Flight Control Unit (FCU), DAU, HUD, GPWS about a RA 1 loss of communication, that Radio Altitude system itself (Radio altimeter, antennas/ coax/strapping) is the most possible cause

1. Swap RA 1 with RA 2.

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

2. Perform a wiring check between RA 1, JB3 and HUDC as follows:
   NOTE: Wh en short circuit is detected, remove all interface components and reinstall one at a time to isolate short.

   From	To	Result
   A67P1-2	A250BP1-G6
   A67P1-10	A250BP1-H6
   GM43-C	A250BP1-J5
   GND	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.

3. Replace HUDC.
4. Do close out.