Narrative:

Aircraft x- [A319]; was docked in hangar bay and mechanics were connecting ground power cable after cleaners boarded. Grounding cable was attached to left hand (lh) main landing gear (medium large transport) and floor ground point. Maintenance manager tech was in flight deck and as another tech switched on power at the wall panel an arc with heavy smoke was noted at lh medium large transport area accompanied by smoke that filled the bay. The tech at wall switch killed ground power as all personnel aboard evacuated.facility staff were summoned to investigate ground power anomaly and check the ground power cord for arcing; loss of ground circuit. A write-up was created summarizing the event and was worked by an [technician] who conducted troubleshooting. The aircraft ground power control unit was replaced and all operational testing determined no faults. The hangar ground power cord was replaced and the removed cable examined; cut for inspection then tested by [technical] staff with no faults found. The aircraft was then released to service with the approval of maintenance control after a short investigation into the matter. Statements from all involved were obtained by operation manager and foreman.the nature of this serious unheard of event is concerning. The high voltage current traveling through the air frame to ground with no known cause should be investigated to the fullest. The airbus ground power control unit should be subject to a tear-down to determine if an internal defect occurred that allowed current to short to the air frame. The grounding cable coil fused to itself with insulator melted off completely. One theory is that the ground power cable was inserted 180 degrees in reverse but that seems very unlikely. This event should be the subject of an alert bulletin for all airbus operators and ground handlers! If an unlucky person was handling this cable during this event they would have been injured or killed from the current or at minimum burned by the arc flash.

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Original NASA ASRS Text

Title: Maintenance person reported heavy smoke was noted in the left hand main landing gear area accompanied by smoke that filled the bay after connecting ground power.

Narrative: Aircraft X- [A319]; was docked in hangar bay and mechanics were connecting ground power cable after cleaners boarded. Grounding cable was attached to Left Hand (LH) Main Landing Gear (MLG) and floor ground point. Maintenance Manager Tech was in flight deck and as another tech switched on power at the wall panel an arc with heavy smoke was noted at LH MLG area accompanied by smoke that filled the bay. The Tech at wall switch killed ground power as all personnel aboard evacuated.Facility staff were summoned to investigate ground power anomaly and check the ground power cord for arcing; loss of ground circuit. A write-up was created summarizing the event and was worked by an [technician] who conducted troubleshooting. The aircraft Ground Power Control Unit was replaced and all operational testing determined no faults. The hangar ground power cord was replaced and the removed cable examined; cut for inspection then tested by [technical] staff with no faults found. The aircraft was then released to service with the approval of Maintenance Control after a short investigation into the matter. Statements from all involved were obtained by Operation Manager and Foreman.The nature of this serious unheard of event is concerning. The high voltage current traveling through the air frame to ground with no known cause should be investigated to the fullest. The Airbus Ground Power Control Unit should be subject to a tear-down to determine if an internal defect occurred that allowed current to short to the air frame. The grounding cable coil fused to itself with insulator melted off completely. One theory is that the ground power cable was inserted 180 degrees in reverse but that seems very unlikely. This event should be the subject of an Alert Bulletin for all Airbus operators and ground handlers! If an unlucky person was handling this cable during this event they would have been injured or killed from the current or at minimum burned by the arc flash.

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.