What happened
On 19 August 2010, a DHC-8-402 Dash 8, registration G-JEDK, was performing a commercial passenger flight from Manchester Airport. Shortly after departing the runway, the senior cabin crew member notified the flight deck of a strange smell and the presence of mist or smoke within the cabin.
As the flight progressed, the smoke density increased, eventually entering the flight deck. During this time, a toilet fire alarm was triggered; however, upon inspection by the cabin crew, no fire was located in the lavatories or overhead lockers. In response to the deteriorating conditions, the flight crew declared a ‘MAYDAY’ and prepared for an immediate return to the airport. As a precautionary measure, the crew deactivated the electrical power to the galley and cabin equipment via circuit breakers and instructed passengers to prepare for an emergency exit.
After approximately 14 minutes of flight, the aircraft landed safely at Manchester Airport. Once the aircraft had come to a complete stop and the engines were shut down, the commander ordered an evacuation. The process was completed in roughly 15 seconds, and all 31 passengers and 4 crew members exited the aircraft without any injuries.
The investigation
The investigation focused on identifying the origin of the smoke that had contaminated the aircraft's interior. Following the incident, an engineering inspection was conducted on the aircraft's propulsion system. This examination established that the smoke had been introduced into the cabin and flight deck via the engine bleed air system.
Findings
- The source of the smoke was a failed internal oil seal within the left engine.
- This mechanical failure resulted in engine oil leaking into the bleed air, which subsequently contaminated the conditioned air supply provided to the passenger and flight deck compartments.