Fault Message:

GEN4 LINE CT OPEN/SHORT FAULT

Fault Code:

2424123LPS

Associated CAS:

GEN 4 FAIL
(Advisory)

Variable Frequency Generator (VFG) 4 has tripped off-line or will not come on-line.

• Generator Control Unit (GCU) 4 (A59)
• Variable Frequency Generator (VFG) 4 (G4)
• AC Power Center (ACPC) (A54)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

A GCU patch cable (GSE REF # 24X-24-02) can be used to swap GCUs 1, 4 and 5 into position 2 or 3 (for troubleshooting only).

The GCU NVMs can only be downloaded at position #2 or #3.

1. Swap GCU 4 with GCU 3 (physically or using the GCU patch cable).
   NOTE: Use PMAT to monitor the fault on GCU.

   1. If system checks are good, replace GCU 4 and do close out.
   2. If fault remains, continue with next step.

2. Disconnect connector PL4 on LCTA 4. Perform continuity check (open circuit= failure) within LCTA 4 as follows:

   From	To	Result
   PL4-1	PL4-4
   PL4-2	PL4-4
   PL4-3	PL4-4

   1. If there is continuity, go to step 4.
   2. If there is no continuity, continue with next step.

3. Replace LCTA 4.

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

4. Disconnect connector GCU 4 (A59P2). Perform continuity check between GCU 4 and LCTA 4 as follows:

   From	To	Result
   A59P2-49	PL4-1
   A59P2-57	PL4-2
   A59P2-63	PL4-3
   A59P2-62	PL4-4

   1. If there is continuity, go to step 7.
   2. If there is no continuity, continue with next step.

5. Disconnect connector ACPC (A54P4). Perform continuity check (open circuit= failure) between GCU 4 and A54P4 as follows:

   From	To	Result
   A59P2-49	A54P4-E
   A59P2-57	A54P4-F
   A59P2-63	A54P4-G
   A59P2-62	A54P4-H

   1. If there is continuity, go to step 8.
   2. If there is no continuity, continue with next step.

6. Repair aircraft wiring between GCU 4 and A54P4 as follows:

   From	To	Result
   A59P2-49	A54P4-E
   A59P2-57	A54P4-F
   A59P2-63	A54P4-G
   A59P2-62	A54P4-H

   1. If system checks are good, do close out.
   2. If fault remains, continue with next step.
      NOTE: Call Bombardier for decision to repair ACPC wiring or replace ACPC.

7. Disconnect connector ACPC (A54P4) and leave PL4 disconnected. Perform wiring checks (short circuit= failure) at connector A54J2 as follow:

   From	To	Result
   A54J2-H	A54J2-E
   A54J2-G	A54J2-E
   A54J2-F	A54J2-E

   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.

8. Replace ACPC.
9. Do close out.