What happened
On November 11, 2013, at the EPKK aerodrome, a Boeing 737-800 was undergoing refueling operations when a fuel leak was detected. Approximately 10 minutes after the refueling process began, fuel started leaking from the right-side fuel drain vent. The refueling operator immediately halted the operation and notified the airport fire brigade, which arrived to secure the area and neutralize the spill.
Roughly three hours later, the same aircraft was scheduled for another refueling session. The refueling vehicle operator notified the new aircraft commander that a leak had occurred during the previous session due to a technical fault. Despite this warning, the aircraft commander configured the refueling control panel, and upon the captain's explicit instruction, the fuel flow from the tanker truck was initiated. This resulted in a second fuel leak from the right wing overflow tank, forcing the airport fire brigade to respond once again to manage the spill.
The investigation
The investigation established that the aircraft's fuel system was subject to a recurring malfunction. Investigators confirmed that the refueling operator had proactively informed the new crew of the previous incident involving the shut-off valve. Furthermore, it was determined that the aircraft had been scheduled for another flight without the necessary inspections or repairs being performed to address the known defect.