Narrative:

While at cruise altitude (FL380) midway through flight; right IRS dc fail EICAS displayed along with dc fail light for approximately 10-20 seconds then extinguished. QRH checklist completed and we decided to continue to [our destination]. Around the same time; we began hearing a clicking sound coming from the area right of the first officer's seat near the right circuit breaker (circuit breaker) panel; printer and AC power outlet. All cbs checked in and clicking stopped for a while. Approximately 10 to 15 minutes later; the clicking sound returned. This stopped after a few minutes and at this point we were near our top of descent. Shortly thereafter; we lost the captain's displays; FMC and the top EICAS display; as well as losing all autopilots and auto throttles. EICAS messages were plentiful...upwards of 30. Captain asked for lower altitude below rvsm airspace and asked for clearance direct to [destination] while breaking out the QRH. First officer flew the airplane. Captain determined that the left AC bus off EICAS message was the source of our problems. He then ran the QRH checklist for left AC bus off. Left AC bus would not reset. Captain selected right instrument source select panel to receive displays and managed flight from right FMS. We initially were on vectors to intercept ILS; but due to flap indicator being inoperative; we chose to back up flap operation with altn flaps. Requested delay vectors to configure properly and discuss flap indications. We decided to use flaps 20 for approach and use [a different runway] for longer landing rollout. In addition; received eqpt ovht message and captain ran appropriate checklist. Approach and landing conducted uneventfully. Maintenance debriefed and aml entry input by captain. Duty officer called and debriefed by captain.

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Original NASA ASRS Text

Title: B757 flight crew reported experiencing an electrical issue resulting in several system rendered inoperative or degraded. Flight landed normally.

Narrative: While at cruise altitude (FL380) midway through flight; R IRS DC FAIL EICAS displayed along with DC FAIL light for approximately 10-20 seconds then extinguished. QRH checklist completed and we decided to continue to [our destination]. Around the same time; we began hearing a clicking sound coming from the area right of the First Officer's seat near the right Circuit Breaker (CB) panel; printer and AC power outlet. All CBs checked in and clicking stopped for a while. Approximately 10 to 15 minutes later; the clicking sound returned. This stopped after a few minutes and at this point we were near our top of descent. Shortly thereafter; we lost the Captain's displays; FMC and the top EICAS display; as well as losing all autopilots and auto throttles. EICAS messages were plentiful...upwards of 30. Captain asked for lower altitude below RVSM airspace and asked for clearance direct to [destination] while breaking out the QRH. First Officer flew the airplane. Captain determined that the L AC BUS OFF EICAS message was the source of our problems. He then ran the QRH checklist for L AC BUS OFF. L AC BUS would not reset. Captain selected Right Instrument Source Select Panel to receive displays and managed flight from right FMS. We initially were on vectors to intercept ILS; but due to Flap indicator being inoperative; we chose to back up flap operation with ALTN flaps. Requested delay vectors to configure properly and discuss flap indications. We decided to use flaps 20 for approach and use [a different runway] for longer landing rollout. In addition; received EQPT OVHT message and Captain ran appropriate checklist. Approach and landing conducted uneventfully. Maintenance debriefed and AML entry input by Captain. Duty officer called and debriefed by Captain.

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.