What happened
On June 13, 2022, an Airbus A320-251N, registration TF-PPA, was operating a scheduled commercial flight from Malaga, Spain, to Keflavik, Iceland. During the flight, the crew received seven simultaneous ECAM advisory messages, including faults related to the autopilot, cabin pressure, and fuel quantity indication.
During subsequent fuel checks, the crew observed a hollow amber triangle on the ECAM, which they interpreted as the fuel transfer valves being in a transition position. This led to concerns that fuel could not be transferred from the outer wing tanks to the inner wing tanks. Fearing the aircraft might land with only approximately 300 kg of usable fuel—far below the planned 1,900 kg—the crew requested a higher flight level and eventually declared a Pan-Pan emergency, later upgrading to an emergency declaration with Reykjavik Control.
As the aircraft approached Keflavik, the fuel levels in the outer tanks began to decrease, and the inner tanks increased, indicating that fuel transfer was indeed occurring. The aircraft landed safely at 01:39 with 2,320 kg of total fuel on board, and no injuries or damage were reported.
The investigation
The RNSA investigation focused on why the aircraft experienced multiple simultaneous system faults and the ambiguous fuel valve indication. Investigators discovered that a specific circuit breaker, FIN 6PN, had been tripped.
Technical analysis revealed that the movement of the observer seat on the flight deck was the likely cause. When a cabin crew member moved the seat from its stowed position, the seatbelt made contact with the circuit breaker panel and tripped the breaker. This loss of power to busbar 206PP prevented the Fuel Quantity Indicating Computer and the Inter Cell Transfer Valves (ICTVs) from operating or providing clear status updates. The investigation also noted that the crew's decision-making was impacted by the ambiguous system cues provided by the ECAM.
Findings
- The tripping of circuit breaker FIN 6PN by the observer seat belt was the primary cause of the electrical fault.
- The loss of power to the relevant busbar created latent technical conditions, including misleading system indications (the hollow amber triangle).
- The flight crew's situational awareness was compromised by the ambiguity of the fuel transfer valve status messages.
- Existing Airbus service bulletins for protective covers on the circuit breaker panels did not extend far enough to cover the specific panel (124VU) where the incident occurred.