The new software upgrade for the PSEU is now available making it a “-5 PSEU”. According to Boeing it improves the recording of faults, reduces nuisance faults and improves troubleshooting
The Dispatch/No Dispatch Fault Annunciation Logic has changed as follows:
1. Dispatch/No Dispatch Fault Annunciation Logic
A flight cycle begins 5 seconds after takeoff (Airplane transitions from Ground to Air). At this point, the PSEU begins recording faults for the current flight cycle.
The PSEU checks for faults detected during the current cycle (to announce) thirty seconds after landing (Air to Ground).
If Non-Dispatchable Faults are detected, the PSEU light in the Aft P5 panel will illuminate spontaneously and remain illuminated until the condition is resolved, or the PSEU is reset. This process did not change from -4. These faults are always viewable through the PSEU BITE display.
If Dispatchable Faults are detected, the PSEU light in the Aft P5 panel will illuminate spontaneously thirty seconds after landing and remain illuminated until both engines are shutdown, or the parking brake is set. The Dispatchable Fault Indication will remain disabled until the next landing. This process changed from -4. These faults are always viewable through the PSEU BITE display.
There are also changes to the following:
• Door Indication and Warning System
• Takeoff Warning System
• Fault History
• BITE Changes