Commercial Fixed Wing
Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 159; Flight Crew Total 12176; Flight Crew Type 533
Distraction; Workload; Troubleshooting; Situational Awareness
Aircraft Equipment Problem Critical; Flight Deck / Cabin / Aircraft Event Passenger Misconduct
Air Traffic Control Provided Assistance; Flight Crew Landed As Precaution; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Diverted
Aircraft
At some point after departure EICAS indicated WINDOW HEAT L FWD and WINDOW HEAT R SIDE. As the Pilot Monitoring; accomplished the irregular checklist which resulted in primary heat being removed from the appropriate windows. Several hours later Captain and I left the cockpit to begin our break. Shortly afterword I was summoned; informed we were diverting to ZZZZ; and returned to the cockpit. I was briefed that upon further investigation it appeared that some 38 circuit breakers had tripped and upon consultation with [Maintenance Control] and Dispatch the decision to divert due to a possible issue with PECS system was made. I concurred with this decision. Also during this time there apparently was an issue with an uncooperative passenger leading to declaring a threat level 1 and law enforcement was requested to meet the aircraft upon arrival. We continued to ZZZZ and landed uneventfully. The entire crew coordination during this event was excellent.
First Officer and myself completed first rest break subsequently receiving a transition briefing on the flight deck from Captain . Our position on the route was in the area of transition to ETOPS entry and Oceanic crossing. With my taking Captain seat on the flight deck and he going on rest break; I reviewed the cockpit discovering a status message: ELEC P300 DISTR CHANNEL and ELEC P100 PANEL. Part of Captain's briefing included an INOP primary L FWD and R SIDE window heat. Curious if the status message was associated with the failure or written up separately in the electronic logbook; I reviewed the electronic log items unable to determine any association or an independent item. Further; First Officer had pulled up the electronic circuit breaker status page to note multiple pages of system discrepancies listed with circuit breaker position 'Unknown'. Unable to research the status message satisfactorily; I called Captain to inquire his knowledge of the situation. He was not familiar with the matter and chose to come up to the cockpit for review; whereby he decided to resume his seat to make a satcom call to [Maintenance Control] with his headset. First Officer and myself continued normal flight duties while listening and commenting as the conversation with [Maintenance Control] continued. The concern from the flight deck were the many critical system circuit breakers in position 'Unknown'; thus possibly affecting normal and/or back up system capabilities. Maintenance Control researched and indicated that the status was dispatchable and deferable for ETOPS. However; with specific review of individual systems queried by Captain; he was not able to ascertain the status of several individual critical systems to include systems like landing gear relays and others. Upon further review; one critical system in particular; the POWER ELECTRONICS COOLING SYSTEM (PECS); the liquid cooling system for the large motor power distribution system in the aft E/E compartment appeared and was stated by [Maintenance Control] to have a pump that was not operable. This was a standout item of concern; among several; to the 3 pilots; [Maintenance Control]; and Dispatch. For me personally having been involved as a ferry crew with [Company's] first PECS replacement involving [Manufacturer] and other lead engineers support; it is a very critical system needing to function properly. I also recalled how some of the MEL script at the time was inaccurate; unsafe; and subscript of how we were ok to continue; dispatch and defer on the ground questionable. With the [oceanic] crossing ahead of us and the status of many of our systems 'Unknown'; the Captain; with multiple sources of input; ultimately made the decision to divert to ZZZZ to address the issue on the ground. The flying First Officer arrived in the cockpit from rest break during the divert and subsequently landed the aircraft. Much of the electrical fault issue was resolved by ZZZZ Maintenance who were familiar and had dealt with the issue on 3 separate occasions. They were successful in resetting much of the faulted channels with the exception of the landing gear specifics. Meanwhile; our pilot crew duty timed out whereby Maintenance continued working to repair. As a side note; luckily with a few hours of work; the repair was complete and a [Company] cargo crew in the EMPTY terminal happened to be available to continue the flight to ZZZ with Status Normal.
Air carrier flight crew reported multiple electrical failures during cruise that resulted in a diversion.