What happened
On 12 March 2014, an Airbus A319, registered F-GRHT, was operating a commercial flight from Marseille to Paris - Charles de Gaulle. During the flight preparation, the crew noted a previous technical log entry regarding fluctuating fuel quantities. Based on the aircraft's gauges, which indicated a fuel on board (FOB) of 5,080 kg, the crew requested additional fuel, bringing the total to 5,000 kg for the leg.
During the climb, the crew observed that the fuel transfer valves from the outer tanks to the inner tanks were open. Shortly after, an ECAM "FUEL L WING TK LO LVL" warning appeared. The crew observed that the fuel quantity indications were fluctuating and, after performing the associated procedure, the warning disappeared. The crew attributed this to a known intermittent sensor issue and decided to monitor the fuel levels manually every few minutes.
As the aircraft descended through FL110, a low-pressure warning for both left engine fuel pumps was triggered. The crew followed the associated procedures but did not open the cross-feed valve. During the descent, the left engine failed and shut down. The crew declared an emergency and landed the aircraft with one engine operative. Upon landing, it was discovered that the left tank was empty, while the right tank contained approximately 1,100 kg of fuel.
The investigation
The BEA investigation focused on the discrepancy between the fuel quantity indicated at departure and the actual fuel on board. Investigators found that the Fuel Quantity Indicating Computer (FQIC) had overestimated the fuel weight by approximately 1,270 kg. The investigation also examined the technical logs and maintenance history, noting that the FQIC had been replaced only nine days prior to the incident.
Technical examinations of the FQIC revealed a solder defect that caused intermittent failures due to voltage variations in an oscillator. Furthermore, the investigation reviewed the crew's use of the Aircraft Technical Log (ATL) and the procedures for managing fuel imbalance and low-level alerts.