What happened
On 1 October 2016, an Airbus A319-111, registration G-EZFX, was performing a commercial passenger flight from La Rochelle Airport, France, to London Gatwick Airport. The aircraft was carrying 105 passengers and six crew members.
Shortly after takeoff, the flight crew detected vibrations that lasted for several minutes before subsiding. However, the vibration returned intermittently throughout the flight. While the aircraft was holding at 12,000 feet (FL120) in preparation for its approach to Gatwick, the vibration recurred alongside a distinct, strong burning smell. Although the odor dissipated quickly, the combination of the vibration and the smell happened again a few minutes later. In response to these developments, the crew donned their oxygen masks, declared a PAN-PAN urgency signal, and requested an immediate landing.
The investigation
The investigation focused on the source of the mechanical vibration and the accompanying odor. The operator identified that the issue originated from a bearing failure within an extractor fan located in the avionics bay.
While a maintenance program was already established to overhaul these specific fans once they reached 20,000 flying hours, the unit involved in this incident failed after 19,363 hours of operation, prior to its scheduled service.