Narrative:

While climbing through FL200 we experienced an electrical malfunction which clicked off the autopilot (a/P) and autothrust (a/T); followed by loud chattering noises and all aural and visual warnings going off continually with constant chimes and all annunciator lights flashing. At the time of the failure the first officer was flying in day VFR conditions. We requested a return back to the departure airport. He continued to fly the aircraft using the stand-by instruments and outside horizon. Most of the equipment and systems on the aircraft were giving false readings; the only flight instruments available to us were the stand-by. The procedure; 'intermittent AC power interruptions'; was attempted with no real changes to the electrical systems. Due to the fact that all the annunciators were flashing; we had a difficult time determining which ones were really on. Next was rt gen off which again was difficult to proceed to completion due to all annunciators flashing. We did as much as possible to gain enough systems and flight instruments to safely conduct an approach and landing. The rt gen off; procedure was followed but without many changes. Since all communication systems were very difficult to use with the loud chattering and chiming; I opened the cockpit door and briefed the #1 flight attendant. We also tested the PA system to make sure it worked so I could brief the passenger; which I did. When I returned my attention to the cockpit my first officer informed me that now my side was working and I took control of the aircraft while he reviewed the QRH procedure again prior to setting up for the approach and landing. When we received the aircraft at the start of the flight; the rt gen off annunciator light was placarded inoperative; and was on continually. There was a history of the light coming on but normal gen operation. When trying to work through both QRH procedures; we could not proceed beyond the first notes pertaining to lights being on because all the annunciator lights were flashing. I suggest more guidance for flight crews when encountering this problem in the future.

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Original NASA ASRS Text

Title: A MD82's electrical system malfunction caused continuous false visual and aural system warnings as well as inaccurate flight instrument displays. Flight returned to the departure airport.

Narrative: While climbing through FL200 we experienced an electrical malfunction which clicked off the autopilot (A/P) and autothrust (A/T); followed by loud chattering noises and all aural and visual warnings going off continually with constant chimes and all annunciator lights flashing. At the time of the failure the First Officer was flying in day VFR conditions. We requested a return back to the departure airport. He continued to fly the aircraft using the stand-by instruments and outside horizon. Most of the equipment and systems on the aircraft were giving false readings; the only flight instruments available to us were the stand-by. The procedure; 'Intermittent AC Power Interruptions'; was attempted with no real changes to the electrical systems. Due to the fact that all the annunciators were flashing; we had a difficult time determining which ones were really on. Next was RT GEN OFF which again was difficult to proceed to completion due to all annunciators flashing. We did as much as possible to gain enough systems and flight instruments to safely conduct an approach and landing. The RT GEN OFF; procedure was followed but without many changes. Since all communication systems were very difficult to use with the loud chattering and chiming; I opened the cockpit door and briefed the #1 Flight Attendant. We also tested the PA system to make sure it worked so I could brief the passenger; which I did. When I returned my attention to the cockpit my First Officer informed me that now my side was working and I took control of the aircraft while he reviewed the QRH procedure again prior to setting up for the approach and landing. When we received the aircraft at the start of the flight; the RT GEN OFF annunciator light was placarded inoperative; and was on continually. There was a history of the light coming on but normal GEN operation. When trying to work through both QRH procedures; we could not proceed beyond the first notes pertaining to lights being on because ALL the annunciator lights were flashing. I suggest more guidance for flight crews when encountering this problem in the future.

Data retrieved from NASA's ASRS site as of July 2013 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.