Narrative:

While in cruise at FL370; the EICAS spontaneously displayed the 'AC ess bus' caution message. A few seconds later; the cockpit went completely dark. The original caution message was then accompanied by several other caution messages. The captain (pilot flying) took the radios and began to call for QRH. However; the flight attendants called on the intercom before we could continue. The captain asked me to take control of the aircraft and the radios while he spoke to the flight attendants. After a brief call; he took the aircraft and radios from me and asked for the QRH. I opened up the QRH and found the checklist for 'AC ess bus.' I verbalized the title and confirmed the checklist with the captain. We then followed the procedure which directed us press the AC ess xfer button which did not restore power. We then referenced the AC synoptic page and found that gen 1 was magenta as mentioned in the QRH. We set gen 1 to the off/reset position and then coordinated a descent to fl 310. Upon leveling off; we started the APU. The 'AC ess bus' message disappeared as soon as the APU generator came online. Once the situation had calmed down; the captain once again gave me control of the aircraft and radios so that he could brief the flight attendants in greater detail and make an announcement to the passengers. The remainder of the flight was uneventful.the cause of the incident was the sudden and unexpected failure of a major component of the electrical system.

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Original NASA ASRS Text

Title: CRJ-900 First Officer reported the cockpit went totally dark due to a generator failure.

Narrative: While in cruise at FL370; the EICAS spontaneously displayed the 'AC ESS BUS' caution message. A few seconds later; the cockpit went completely dark. The original caution message was then accompanied by several other caution messages. The Captain (Pilot Flying) took the radios and began to call for QRH. However; the flight attendants called on the intercom before we could continue. The Captain asked me to take control of the aircraft and the radios while he spoke to the flight attendants. After a brief call; he took the aircraft and radios from me and asked for the QRH. I opened up the QRH and found the checklist for 'AC ESS BUS.' I verbalized the title and confirmed the checklist with the Captain. We then followed the procedure which directed us press the AC ESS XFER button which did not restore power. We then referenced the AC synoptic page and found that GEN 1 was magenta as mentioned in the QRH. We set GEN 1 to the OFF/RESET position and then coordinated a descent to FL 310. Upon leveling off; we started the APU. The 'AC ESS BUS' message disappeared as soon as the APU generator came online. Once the situation had calmed down; the Captain once again gave me control of the aircraft and radios so that he could brief the flight attendants in greater detail and make an announcement to the passengers. The remainder of the flight was uneventful.The cause of the incident was the sudden and unexpected failure of a major component of the electrical system.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.