Fault Message:

GEN4 DRIVE SHAFT FAIL/INVALID % N2

Fault Code:

2424200LPS

Associated CAS:

GEN 4 FAIL
(Advisory)

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

• Variable Frequency Generator (VFG) 4 (G4)
• Generator Control Unit (GCU) 4 (A59)
• Associated Wiring

Advisory Wire/Service Bulletin: 

• AW700-24-0598 - Variable Frequency Generator (VFG) GL511-1103-9 - Failure

Full Throttle Blog/Forum Articles/Infoservice/Newsletter:

• Reference Instruction Letter (RIL) GX-0198 - Return to service following VFG bearing failure and/or VFG housing rupture.

Flight Operation Notifications Manual (FONM): None

NOTES:

• Prior to T/S procedures, perform a visual of generator 4 for heat distress. Confirm if the heat exchanger is blocked with FOD.
• 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. Access CAIMS and check if the following faults are active:

   • 2424124LPS - GEN4 [DIFF PROTECTION FEEDER]
   • 2424126LPS - GEN4 OIL OVERTEMP FAULT

   Inspect the VFG for the following:

   • VFG oil filter bypass indicator tripped, and/or
   • Metal particles in the oil lines, and/or
   • VFG end frame cracked or breached, and/or
   • Oil sight glass cracked

   1. If there is a combination of the listed CAIMS active fault and VFG condition(s) perform RIL GX-0198
   2. If there is NO combination, continue with next step.

2. Do a visual inspection of the VFG. Is the drive shaft broken or sheared?

   1. If YES, investigate the cause and replace VFG 4.
   2. If NO, continue with next step.

3. Interchange the GCU 4 with GCU 2 (physically or using the GCU patch cable).
   NOTE: Use CAIMS 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.

4. Disconnect VFG 4 connector G4P1 and GCU 4 connector A59P1. Do a continuity check as follows:

   From	To	Result
   A59P1-E	Ground
   A59P1-F	Ground
   A59P1-G	Ground

   1. If there is continuity, repair defective wiring as required.
   2. If there is NO continuity, continue with next step.

5. Do a continuity check between GCU 4 and VFG 4 as follows:

   From	To	Result
   A59P1-E	G4P1-G
   A59P1-F	G4P1-C
   A59P1-G	G4P1-L

   1. If there is continuity, continue with next step.
   2. If there is NO continuity, repair defective wiring as required.

6. Interchange VFG 4 with VFG 3.

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

7. Disconnect ACPC connector A54P2 and GCU 4 connector A59P2. Perform wiring check between A59P2 and A54P2 as follow:

   From	To	Result
   A59P2-9	A54P2-a
   A59P2-15	A54P2-b

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

8. Replace ACPC.
9. Do close out.