Narrative:

At approximately xa:45Z, FL390 I began to notice the cockpit lights (overhead and panel lights background) flicker as if there was a power interruption, there weren't any ECAM msgs associated with it. The purser called and informed us that the right side cabin lights were flickering on and off. Additionally, the video screens on the right side were retracting and extending on their own. At the same time the first officer's nd and pdf flickered on and off including moments of loss of flight data to the displays. The ECAM began to cycle msgs about the number 2 yaw damper, pack control, pitch trim, fwc, autoplt and possibly others. The purser then informed us that she smelled smoke. The first officer agreed that he also smelled smoke. While none was visible it had an electrical arcing smell to it. At this time we were approximately 30 NM from ZZZ. Considering the report of smoke and or smell I suggested to the first officer that we begin an immediate diversion as a precaution, he agreed. ZZZ was considered and used for the following reasons: close proximity, WX was VFR, it was an air carrier base, it was in our database, good airport facility, and the size of the town was conducive to having acceptable emergency facility. He agreed. After donning our oxygen masks and completing the initial qrc 'smoke and fumes' checklist we began our descent and then declared an emergency. I informed the purser that we would be landing at ZZZ, she reminded me that we had a deadheading pilot on board and would we like for him to come to the cockpit and help. Great idea, I had him come to the cockpit and help run the required checklists for us. I handed him the qrc/checklist card and the A320 flight manual to complete the current checklist and back us up on the approach and final checklist. He did a great job. The descent from FL390 to landing took about 10+ min. ATC provided great vectors to final and had called the ZZZ tower telling them of our possible problem. They, the ZZZ tower, subsequently called the fire and crash crews to the airport and were there when we landed. I considered the possibility of an evacuate/evacuation however, because the smell had dissipated and the ECAM's had subsided I conferred with the purser and felt it was not necessary. I believe I also informed her that this was 'cabin advisory' and to be ready should we need to evacuate/evacuation on landing. While talking to the tower I told them we would probably not need the crash equipment. The landing was normal and there were no problems taxing in to the ramp area. A normal shutdown was completed. Callback conversation with reporter revealed the following information: the reporter stated all the right cockpit and cabin lights were flickering and the cabin passenger video screens were retracting and extending continuously. The reporter said the first officer experienced loss of flight data to the primary displays and the ECAM began to cycle msgs about the yaw damper, pack control, pitch trim and numerous other systems. The reporter stated the first officer smelled smoke associated with electrical arcing and the same smell was reported by the purser, but no smoke was visible. The reporter said the decision was made to declare an emergency and divert immediately. The reporter stated at no time during this event did the ECAM indicate this was a generator loss of phase problem. The reporter said maintenance found a feeder wire pin in the firewall connector burned with evidence of severe arcing. The reporter stated the failure of the ECAM system to warn of a right bus intermittent loss of phase was reported and discussed with the company.

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Original NASA ASRS Text

Title: AN A320 IN CRUISE AT FL390 DECLARED AN EMER AND DIVERTED DUE TO R AC BUS CAUSING FLICKERING LIGHTS IN COCKPIT AND CABIN. FO FLT INSTRUMENTS INTERMITTENT AND NUMEROUS ECAM ALERTS.

Narrative: AT APPROX XA:45Z, FL390 I BEGAN TO NOTICE THE COCKPIT LIGHTS (OVERHEAD AND PANEL LIGHTS BACKGROUND) FLICKER AS IF THERE WAS A POWER INTERRUPTION, THERE WEREN'T ANY ECAM MSGS ASSOCIATED WITH IT. THE PURSER CALLED AND INFORMED US THAT THE R SIDE CABIN LIGHTS WERE FLICKERING ON AND OFF. ADDITIONALLY, THE VIDEO SCREENS ON THE R SIDE WERE RETRACTING AND EXTENDING ON THEIR OWN. AT THE SAME TIME THE FO'S ND AND PDF FLICKERED ON AND OFF INCLUDING MOMENTS OF LOSS OF FLT DATA TO THE DISPLAYS. THE ECAM BEGAN TO CYCLE MSGS ABOUT THE NUMBER 2 YAW DAMPER, PACK CTL, PITCH TRIM, FWC, AUTOPLT AND POSSIBLY OTHERS. THE PURSER THEN INFORMED US THAT SHE SMELLED SMOKE. THE FO AGREED THAT HE ALSO SMELLED SMOKE. WHILE NONE WAS VISIBLE IT HAD AN ELECTRICAL ARCING SMELL TO IT. AT THIS TIME WE WERE APPROX 30 NM FROM ZZZ. CONSIDERING THE RPT OF SMOKE AND OR SMELL I SUGGESTED TO THE FO THAT WE BEGIN AN IMMEDIATE DIVERSION AS A PRECAUTION, HE AGREED. ZZZ WAS CONSIDERED AND USED FOR THE FOLLOWING REASONS: CLOSE PROXIMITY, WX WAS VFR, IT WAS AN ACR BASE, IT WAS IN OUR DATABASE, GOOD ARPT FAC, AND THE SIZE OF THE TOWN WAS CONDUCIVE TO HAVING ACCEPTABLE EMER FAC. HE AGREED. AFTER DONNING OUR OXYGEN MASKS AND COMPLETING THE INITIAL QRC 'SMOKE AND FUMES' CHKLIST WE BEGAN OUR DSCNT AND THEN DECLARED AN EMER. I INFORMED THE PURSER THAT WE WOULD BE LNDG AT ZZZ, SHE REMINDED ME THAT WE HAD A DEADHEADING PLT ON BOARD AND WOULD WE LIKE FOR HIM TO COME TO THE COCKPIT AND HELP. GREAT IDEA, I HAD HIM COME TO THE COCKPIT AND HELP RUN THE REQUIRED CHKLISTS FOR US. I HANDED HIM THE QRC/CHKLIST CARD AND THE A320 FLT MANUAL TO COMPLETE THE CURRENT CHKLIST AND BACK US UP ON THE APCH AND FINAL CHKLIST. HE DID A GREAT JOB. THE DSCNT FROM FL390 TO LNDG TOOK ABOUT 10+ MIN. ATC PROVIDED GREAT VECTORS TO FINAL AND HAD CALLED THE ZZZ TWR TELLING THEM OF OUR POSSIBLE PROB. THEY, THE ZZZ TWR, SUBSEQUENTLY CALLED THE FIRE AND CRASH CREWS TO THE ARPT AND WERE THERE WHEN WE LANDED. I CONSIDERED THE POSSIBILITY OF AN EVAC HOWEVER, BECAUSE THE SMELL HAD DISSIPATED AND THE ECAM'S HAD SUBSIDED I CONFERRED WITH THE PURSER AND FELT IT WAS NOT NECESSARY. I BELIEVE I ALSO INFORMED HER THAT THIS WAS 'CABIN ADVISORY' AND TO BE READY SHOULD WE NEED TO EVAC ON LNDG. WHILE TALKING TO THE TWR I TOLD THEM WE WOULD PROBABLY NOT NEED THE CRASH EQUIP. THE LNDG WAS NORMAL AND THERE WERE NO PROBS TAXING IN TO THE RAMP AREA. A NORMAL SHUTDOWN WAS COMPLETED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED ALL THE R COCKPIT AND CABIN LIGHTS WERE FLICKERING AND THE CABIN PAX VIDEO SCREENS WERE RETRACTING AND EXTENDING CONTINUOUSLY. THE RPTR SAID THE FO EXPERIENCED LOSS OF FLT DATA TO THE PRIMARY DISPLAYS AND THE ECAM BEGAN TO CYCLE MSGS ABOUT THE YAW DAMPER, PACK CTL, PITCH TRIM AND NUMEROUS OTHER SYSTEMS. THE RPTR STATED THE FO SMELLED SMOKE ASSOCIATED WITH ELECTRICAL ARCING AND THE SAME SMELL WAS RPTED BY THE PURSER, BUT NO SMOKE WAS VISIBLE. THE RPTR SAID THE DECISION WAS MADE TO DECLARE AN EMER AND DIVERT IMMEDIATELY. THE RPTR STATED AT NO TIME DURING THIS EVENT DID THE ECAM INDICATE THIS WAS A GENERATOR LOSS OF PHASE PROB. THE RPTR SAID MAINT FOUND A FEEDER WIRE PIN IN THE FIREWALL CONNECTOR BURNED WITH EVIDENCE OF SEVERE ARCING. THE RPTR STATED THE FAILURE OF THE ECAM SYS TO WARN OF A RIGHT BUS INTERMITTENT LOSS OF PHASE WAS RPTED AND DISCUSSED WITH THE COMPANY.

Data retrieved from NASA's ASRS site as of July 2007 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.