What happened
On 31 December 2020, an Air France Airbus A330-200, registration F-GZCJ, was operating a scheduled commercial flight from Brazzaville, Republic of Congo, to Paris-Charles de Gaulle. While cruising at FL 380 over Chad, the flight crew identified a discrepancy in fuel quantities, noting a deficit of approximately 1.4 tonnes. After the captain briefly left the cockpit for a rest period, the remaining crew observed the loss increasing to roughly 2.1 tonnes.
Following the identification of a potential leak on the left side, the crew initiated the Quick Reference Handbook (QRH) fuel leak procedures. Although the procedure suggested shutting down the affected engine to verify the leak source, the crew elected to keep both engines running to maintain operational stability. The aircraft diverted to N’Djamena airport in Chad.
During the approach and landing, the Runway Overrun Prevention System (ROPS) activated due to heavy braking. Upon arrival at the parking area, the crew shut down the engines sequentially. Firefighters were on standby and applied water to the area under engine 1 to mitigate potential fire risks. There were no injuries among the 136 passengers and 11 crew members on board.
The investigation
The BEA investigation focused on the origin of the fuel loss and the crew's decision-making process. Investigators examined the aircraft's flight recorders and analyzed the fuel system components. The investigation identified a leak at the mounting flange of the Primary Fuel Hose (PFH) on the left engine. Technical analysis revealed that the aircraft was fitted with an older design of the mounting flange, which had a different internal diameter compared to a newer, updated version.
Findings
- The primary cause of the incident was a fuel leak originating from the interface between the engine pylon and the Primary Fuel Hose (PFH) mounting flange.
- The leak occurred at the mounting flange of the PFH on engine 1.
- The aircraft was equipped with an older design of the mounting flange; a newer design had been made available via a service bulletin to address alignment issues, but the old design remained in use.
- Approximately 5.7 tonnes of fuel were lost during the flight and taxiing, with 5.3 tonnes lost while in flight.
- The crew chose to continue operating on two engines rather than shutting down the left engine to confirm the leak source, a decision driven by the desire to avoid the complexities of single-engine flight.