What happened
On 28 August 2014, an Airbus A320-214, registration G-EZWM, was performing a commercial passenger flight from Liverpool to Naples. While climbing through FL320 over Oxfordshire, the co-pilot noticed an unusual odour. As the commander attempted to contact the cabin manager via the interphone, visible smoke was observed rising from the centre console area near the co-pilot's knee.
In response to the smoke, the flight crew donned oxygen masks. The aircraft's Electronic Centralised Aircraft Monitoring (ECAM) system subsequently displayed an avionics smoke alert, accompanied by an amber smoke light and fault indications regarding the blower and extract pushbuttons. The crew declared a PAN-PAN call and initiated a descent. To manage the emergency, the commander delegated flight controls and communications to the co-pilot, allowing the commander to focus on the Quick Reference Handbook (QRH) procedures, passenger briefings, and reprogramming the flight computer for a diversion.
The aircraft diverted to London Gatwick Airport. During the descent, the visible smoke ceased, and the aircraft landed safely on Runway 26L. Upon arrival, the Airport Fire Service escorted the aircraft to a remote stand. A thermal imaging scan of the aircraft by emergency services revealed no hot spots.
The investigation
Technical inspections following the incident identified that a static inverter, located in the avionics bay, had suffered severe overheating. This specific component is responsible for providing 115VAC and 60 Hz power to a utility socket in the cockpit, which is used for plugging in devices such as laptops. Although the inverter is a standalone unit mounted below the co-pilot's footwell, the floor is not sealed, which allowed fumes from the avionics bay to enter the cockpit.
The inverter was sent to the manufacturer for analysis. Their examination revealed that a capacitor (C306) had been destroyed by heat. While the manufacturer could not determine the exact cause of the capacitor's failure, they noted that the component was rated for temperatures well above what it experienced during the incident. The manufacturer also found the overall reliability and failure rates of the inverter units to be within acceptable limits.