What happened
On 27 June 2011, an Embraer 195, registration G-FBEJ, was conducting a commercial passenger flight when the crew encountered smoke and a strong sulphur-like odour within the cabin. The incident occurred as the aircraft was climbing through 10,000 feet. In response to the deteriorating air quality, the flight crew donned oxygen masks and declared a PAN-PAN emergency, deciding to return to Southampton Airport.
After roughly five minutes of flight, the smoke and smell dissipated. The aircraft subsequently completed its landing at Southampton without any further complications or injuries to the 2/4 passengers or 5 crew members on board.
The investigation
Following the event, the AAIB investigated the cause of the smoke. It was determined that one of the aircraft's air conditioning packs had failed during the flight. Upon returning the unit to the manufacturer for a detailed strip inspection, investigators discovered that the second stage turbine rotor had suffered a seizure.
This specific failure mode is a recognized issue caused by a resonance condition within the second stage turbine. To address this, Service Bulletin SB 190-21-0029 had been released in April 2010, which recommended installing a modified turbine with additional nozzle vanes to prevent such damage. The investigation established that the pack involved in this incident had not yet been updated with this modification.