A319 flight crew reported the loss of number 2 generator in flight with the bus cross tie breaker not operating caused a load shedding event. The flight crew elected to descend to improve APU in flight start performance. The flight crew elected to divert and make a precautionary landing after number 2 generator tripped again.
Synopsis
A319 flight crew reported the loss of number 2 generator in flight with the bus cross tie breaker not operating caused a load shedding event. The flight crew elected to descend to improve APU in flight start performance. The flight crew elected to divert and make a precautionary landing after number 2 generator tripped again.
Narrative
Aircraft X; ZZZ to ZZZ1; immediately after level off at FL 390; experienced an audible and visible electrical swap; followed by loss of multiple displays; lights; and multiple Electronic Centralized Aircraft Monitor cautions. Autopilot 2; Auto Thrust; First Officer Primary Flight Display; Navigation Display; and lower Electronic Centralized Aircraft Monitor were all failed. I took controls and Comms while First Officer commenced Electronic Centralized Aircraft Monitor actions. Electronic Centralized Aircraft Monitors displayed in order: Eng 2 Engine Pressure Ratio Mode fault; AC Bus 2 fail; DC Bus 2 fail; Gen 2 fault; NAV LS tuning disagree. I engaged Auto Pilot 1; while manually adjusting thrust. I performed a radio check with ATC and informed them we were dealing with an electrical fault; however no assistance was required. Lead Flight Attendant called to inform us all power and lights were out in the cabin.When [the] First Officer performed Gen 2 fault Electronic Centralized Aircraft Monitor; the Gen Reset; and we regained AC and DC bus 2. We realized then we had experienced a Gen 2 Trip and the Bus Tie had not worked; resulting in the loss of two main busses. The Eng 2 Engine Pressure Ratio MODE fault did not clear. We attempted the published FM reset for this malfunction and it did not work. With [the] situation stabilized; First Officer took controls back; and we agreed to descend to FL 310 per FM guidance to improve APU start capability. I contacted Dispatch and Maintenance Control while [the] First Officer coordinated altitude change for APU start.At this point Gen 2 failed again; however; this time; the bus tie operated correctly and we did not lose AC and DC bus2. Gen 1 powered all busses except normal galley shed. Reset of Gen 2 did not work this time. The First Officer descended to FL310 and started the APU. Bus tie worked and APU Gen successfully powered right side of electrical system. First Officer climbed aircraft back to FL350 to exit a layer of IMC at FL310. Finally able to consult with Maintenance Control after the latest Gen fault; they confirmed from their report downloads what we assessed from all of the Electronic Centralized Aircraft Monitor cautions.They asked us to attempt another reset of the Eng 2 Engine Pressure Ratio mode; which was unsuccessful. We operated the remainder of the flight with both engines in N1 degraded mode. Maintenance Control opined that; although the electrical system was currently powered; there were questions about the efficacy of the bus tie system; and any subsequent potential electrical faults made it prudent to not continue flight to ZZZ1; but rather stop short. Flight crew and Dispatch agreed. Dispatch mentioned ZZZ2; which we had just passed. First Officer and I felt it was just as safe to continue to ZZZ3.By the time we could perform all of our briefs and planning we we would be descending to ZZZ3 and we were about 45 [to] 50 minutes away. The weather was good; and it would be better for our passengers and maintenance. Maintenance Control and Dispatch agreed that a divert to ZZZ3 was a great option. I took the controls back; the First Officer coordinated clearance to ZZZ3 via the ZZZZZ arrival. We did not request priority. We conducted a visual approach and uneventful landing to Runway XXC at ZZZ3.
Second reporter narrative
I was the Pilot Flying on Aircraft X ZZZ [to] ZZZ1. We had just leveled off at our final altitude about 25 minutes after take-off. The Captain had just made a PA announcement turning off the seat belt signs. We agreed to go to speaker and as I switch my loud speaker on; I heard a power swap and I lost my (First Officer side) Primary Flight Display; Navigation Display; and the System Display screens. We immediately transferred the flight controls to the Captain and determined the Autopilot and Autothrust were off. We had multiple Electronic Centralized Aircraft Monitors and the Flight Attendants where buzzing us up front. We briefly discussed that the Captain would fly; take the radios; and I would work the Electronic Centralized Aircraft Monitors.The Flight Attendants started pounding on the Flight Deck door. Captain buzzed the Purser who informed us that the Cabin had gone completely dark. He told her we were working on it and would get back to her. I started completing the blue to do items on the Electronic Centralized Aircraft Monitor. It seemed like we had a cascading amount of Electronic Centralized Aircraft Monitors. From the best of my memory the order of the Electronic Centralized Aircraft Monitors were: Eng 2 Engine Pressure Ratio Mode Fault; Electrical DC Bus 2 Fault; Electrical AC Bus 2 Fault; Electrical Gen 2 Fault (At this point the generator came back online); Auto FLT Facility 2 Fault; NAV LS Tuning Disagree; and lastly Automatic Dependent Surveillance-Broadcast Reporting Fault.When I had completed the above Electronic Centralized Aircraft Monitors and got to the Status Page; we had the following Status (Attachment 1): Eng 2 N1 Degraded Mode; Center TK Fuel UNUSABLE. We had the following INOP Systems: Auto Throttle; Category 2 Center TK PUMPS. At this point we did Electronic Centralized Aircraft Monitor complete screens normal." The Captain checked in with the Flight Attendants and determined that power was restored in the cabin. The Captain made an announcement to the Passengers explaining that we had an electrical issue but have resolved it. The Captain and I then discussed what exactly we had lost since most of the Electronic Centralized Aircraft Monitors had gone away or fixed themselves. We started back in the Quick Reference Handbook to read the Notes/Warnings/Cautions on the items we recalled on the Electronic Centralized Aircraft Monitor.At this point; [we] decided that we had Engine Pressure Ratio Mode Fault and resulting Generator fault which resets normally; but for some reason; the left side did not properly pick up the electrical load. We made a decision to continue since the Gen was reset and decided to consult with Maintenance Control further. The Captain and I exchanged flight controls back to me and then he started coordinating with dispatch to get a VHF patch with Maintenance Control. As Maintenance Control was coming on the line; we had another Electronic Centralized Aircraft Monitor pop up: ELECTRICAL Gen 2 Fault. Captain completed the Electronic Centralized Aircraft Monitor; and this time the reset was unsuccessful. Captain and I both decided for peace of mind the get the APU running and have it as a backup generator. We briefly discussed the APU start limits; and decided the descend to 31000 ft. in order to better guarantee a start. While Captain troubleshot with Maintenance Control and Dispatch; I requested a descent to 31000 ft. and started the APU. While this was all happening; we had been traversing an area of weather below us. We ended up right near the tops at 31000 ft.; and we decided to climb back up to 35000 ft. for a better ride and less chance of a need for anti-ice while making a determination of diverting or not. After the Captain had determined with Maintenance Control that Gen 2 was completely busted we (Dispatch; Maintenance Control; Flight Crew) were all in agreement to divert instead of continue to ZZZ1. At this point in the flight; we were about 45 minutes fromZZZ3. With the weather below us and ZZZ3 VFR we decided on diverting to ZZZ3. I requested clearance from ATC to ZZZ3 while the Captain briefed the Flight Attendants and passengers. The Captain and I discussed whether to request priority handling at this point. We had come across nothing in the Quick Reference Handbook or Electronic Centralized Aircraft Monitors that suggested a sense of urgently to request priority. We had completed the Electronic Centralized Aircraft Monitors and had an extra generator with the APU. We elected not to request priority and just continue normally with the divert to ZZZ3. We exchanged the flight controls again and the Captain was Pilot Flying and I was Pilot Monitoring. The approach and landing were uneventful and we were greeted at ZZZ3 by Maintenance. Attachment 2: Final recall Electronic Centralized Aircraft Monitor screen."
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.