Cabin Fumes from Non-Fire Sources

Cabin Fumes from Non-Fire Sources

Description

Fumes from various non-fire related sources may sometimes be experienced within the cabins of passenger aircraft.

Sources

Most modern passenger aircraft are equipped with pressurised, climate-controlled cabins. In spite of the aircraft designers’ intentions, unwanted fumes frequently permeate the interior of the aircraft. Open doors and hatches as well as certain on-board sources can introduce fumes to the cabin environment. However the usual path of entry for fumes is via the aircraft pressurisation and air conditioning systems.

The majority of passenger aircraft utilise bleed air from the engine or auxiliary power unit (APU) to pressurize and heat or cool the aircraft cabin. As a consequence, any contaminants introduced into the engine/APU compressor prior to the point from which the bleed air is extracted may result in the appearance of corresponding fumes in the passenger cabin and flight deck.

Common sources of fumes ingested through engine compressors include exhaust from other aircraft on ramps or taxiways. In addition, an engine that has just had a compressor wash may emit a noticeable odor during its next startup.

Accidents and Incidents

On 9 February 2023, a Boeing 777-200ER was en route near Marseille when the cabin crew observed smoke coming from a rear galley oven, which was spreading into the rear passenger cabin. After an initial use of multiple Halon fire extinguishers, the smoke ceased after about 20 minutes, but the fumes remained. Although this meant no ongoing emergency existed, some cabin crew and passengers experienced breathing difficulties and it was decided to return to Amsterdam. The cabin crew response to the situation was subsequently assessed as contrary to applicable procedures and relevant cabin crew training seemingly inadequate.

On 23 February 2016, a Boeing 737-800 departing New Chitose encountered sudden-onset and unforecast heavy snowfall whilst taxiing out. When the right engine ran down and cabin crew reports of unusual smells in the cabin and flames coming from the right engine were received, it was decided that an emergency evacuation was required. During this evacuation three passengers were injured, one seriously. The engine fire was found to have been in the tailpipe and caused by an oil leak due to engine fan blade and compressor icing which had also led to vapourised engine oil contaminating the air conditioning system.

On 16 March 2020, a PW150A-powered Bombardier DHC8-400 crew declared a PAN and turned back to Port Moresby after abnormal fumes and (much later) some visible ‘smoke’ which had become apparent after takeoff began to intensify causing some passengers breathing difficulties. Once clear of the landing runway, a precautionary rapid disembarkation was completed. The Investigation found that the source of the smoke/fumes was oil leaking from a failed right engine bearing seal. The failure was found to have occurred ahead of the recommended inspection interval for the seal concerned, a risk which engine manufacturer Pratt & Whitney Canada was aware of.

On 15 December 2019, an Airbus A330-200 turned back to Sydney shortly after departure when a major hydraulic system leak was annunciated. The return was uneventful until engine shutdown after clearing the runway following which APU use for air conditioning was followed by a gradual build up of hydraulic haze and fumes which eventually prompted an emergency evacuation. The Investigation found that fluid leaking from ruptured rudder servo hose had entered the APU air intake. The resulting evacuation was found to have been somewhat disorganised with this being attributed mainly to a combination of inadequate cabin crew procedures and training.

On 5 August 2019, an Airbus A321 crew declared a MAYDAY immediately after clearing the landing runway at Valencia when a hold smoke warning was annunciated. An emergency evacuation was completed without injuries. This warning followed “white smoke” from the air conditioning system entering both the passenger cabin and flight deck in the four minutes before landing which had prompted the pilots to don oxygen masks. The Investigation found the white smoke was the direct consequence of an oil leak from the right engine as a result of the misalignment and breakage of a bearing and its associated hydraulic seal. 

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