What happened
On December 8, 2013, during ground operations at EPPO, an incident occurred while connecting an external power source to an Embraer 170. After the aircraft's power source was connected and the generator set was started, ground personnel observed a flash within the power socket. The generator was immediately shut down to prevent further damage.
Following the flash, an inspection of the aircraft revealed that the external components of the ground power connection panel had been burned. Specifically, damage was found on the socket contacts, the control panel, the fuses, and the compartment cover. While the external interface was damaged, the internal wiring and installation remained intact. The generator plug was also destroyed by high temperatures and fire. The incident took place after dusk during light rain.
The investigation
The investigation examined the condition of the aircraft's electrical interface and the functionality of the generator set. Testing of the generator's parameters and all integrated safety protections showed no malfunctions or irregularities. The investigation also reviewed several subsequent, nearly identical incidents occurring at different airports and involving different organizations to identify patterns in ground handling errors.
Findings
- The primary cause of the incident was the connection of the ground power plug without sufficiently verifying the cleanliness of the contacts, which led to a short circuit between the contacts within the power plug.
- The investigation noted that despite existing instructions in ground power unit procedures, similar events have recurred, suggesting a potential lack of adequate supervision over personnel performing ground handling tasks.