Global 7500 fly-by-wire system – OMS – REU internal fault
Effectivity: Global 7500 aircraft
ATA: 27
By: Daniel Genois – Technical Support The Global 7500 aircraft has complex logics associated to the Remote Electronic Unit (REU) internal faults in the Onboard Maintenance System (OMS).
The “REU internal fault” reported in the OMS can influence/mislead troubleshooting efforts because it can be generated by conditions that are either internal or external to the REU.
The OMS allows to visualize which labels and bits have triggered an OMS fault equation. This is applicable to all OMS active faults, but also to faults logged in the fault history.
As an example, listed below are all labels and bits associated to the “2711006RIBREU – RIB AIL REU (A414) INTERNAL FAULT/REPORTED BY PFCC IN CONTROL” OMS fault logic.
In the example below, the PFCC_1-2 024 14 ROB RIB AIL CCDL Stale Fault = 1 suggests at the CCDL data bus between the ROB and RIB Aileron REUs. The ROB Aileron REU could also be at fault, causing the RIB AIL REU (A414) INTERNAL FAULT to be reported.
PFCC_1-2 027 22 RIB AIL REU Int Pwr Fault = 0
PFCC_1-2 030 15 ROIB Ail EHSV Cmd Fault = 0
PFCC_1-2 031 11 RIIB Ail EHSV Cmd Fault = 0
PFCC_1-2 376 28 RIB AIL REU PBIT Fail REU = 0
PFCC_1-2 264 17 RIB AIL ABIT FAIL Csol = 0
PFCC_1-2 027 24 RIB AIL REU Wrap CCDL 10 Fault = 0
PFCC_1-2 027 25 RIB AIL REU Wrap CCDL 2 Fault = 0
PFCC_1-2 024 15 ROB RIB AIL CCDL Input Fault = 0
PFCC_1-2 024 14 ROB RIB AIL CCDL Stale Fault = 1
PFCC_1-2 311 12 RIIB AIL DM Cmd Flt = 0
PFCC_1-2 311 14 ROIB AIL DM Cmd Flt = 0
PFCC_1-2 312 17 RIB AIL REU RIIB AIL DM Cmd Flt = 0
PFCC_1-2 312 18 RIB AIL REU ROIB AIL DM Cmd Flt = 0
PFCC_1-2 351 19 RIB AIL TTP2 Stale Fault = 0
PFCC_1-2 352 26 RIB AIL TTP2 Internal Fault = 0
PFCC_1-2 234 1.FBW MISC REU MAINT FAULTS 3 22 RIB Ail REU Wrap TTP Fault = 0
To visualize the labels and bits that have set an OMS equation, please refer to "FBW FAULTS - TIPS AND RESETTING METHODS" Section 9.a in SmartFix Plus.
Summary:
Do not take for granted that an REU internal fault OMS message requires an REU replacement. When an REU internal fault is present in the OMS, look for other OMS faults that may have a link to the above labels and bits and follow the associated SFP before replacing an REU. Please refer to AW700-27-0873 that includes REU internal faults scenarios.
The REU internal faults OMS logics will be improved in future OMS software updates for clarity. Please note that the above article will be included in SmartFix Plus under Fly by Wire Tips and the resetting method document will be accessible from most of the FBW faults (Troubleshooting Tips section).