Incident Details
On December 8, 2013, after connecting a ground power unit to an Embraer 170 aircraft at EP PO (Poznań-Ławica Airport), a ground crew member observed a flash at the power receptacle. The ground power unit was immediately shut down. Inspection revealed that external parts of the ground power connection panel, including the receptacle contacts, control panel, fuses, and the cover housing these components, were damaged by heat and fire. The plug of the ground power unit was also destroyed by high temperature and fire. Internal wiring of the aircraft's power system was not damaged. Testing of the ground power unit and its protective devices showed no abnormalities. The incident occurred after dusk with light rain.
Investigation Findings
The investigation, concluded on February 22, 2016, was conducted by the operator under the supervision of Edward Łojek. The cause was determined by analyzing the circumstances and subsequent similar incidents (registered under numbers 116/14, 148/14, 159/14, 167/14, 168/14, 92/16). The commission noted that earlier suspected causes were excluded, and the root cause was identified as the ground power plug being connected without adequately verifying the cleanliness of its contacts, leading to a short circuit between the plug contacts.
Probable Cause
The probable cause of the incident was connecting the ground power plug without sufficiently checking the cleanliness of its contacts, which led to a short circuit between the contacts in the power plug.
Recommendations
No safety recommendations were issued by the investigation commission.