In BGA or ATR's what are the major causes of ODOR in Cabin or Smoke in Cabin? There are some of the maintenance activities that are related to removal of Engines or APU. Removal reason: Smoke in cabin or Odor in cabin what do you think could be different reasons around it? and is there any ways we can avoid it that can be thought of or detect Odor in the bleed Duct itself?
The use of compressed “bleed” air for aircraft ventilation and pressurization systems commenced in military jet aircraft in the late 1940s. However, early commercial jet aircraft, such as the Boeing 707 and Douglas DC-8, initially did not take air from the engine compressor to supply the breathing/ventilation air, but instead they relied on drawing air from outside the aircraft using separate turbo compressors. The system of utilizing compressor bleed air to supply aircraft breathing air is today used in almost all commercial transport aircraft except for the new Boeing B-787. The B-787 utilizes an electric compressor system which acquires fresh air directly from outside, rather than through the engines. Bleed air (used on most aircraft) is not filtered before it enters the air supply. This air is diverted from the mainstream gas path for several purposes, including cooling, anti-icing and cabin pressurization. A variety of air and oil seals are installed in order to minimize the amount of oil leakage from the gas turbine compressors and into the bleed air supply. However, just about all known seals leak and there is no such thing as a seal that does not leak. Only a very small amount of oil is need to leak through a seal to generate a noticeable cabin odor. And, it will be possible to smell the oil long before high oil consumption is noticed. Light oil contamination, well below permissible leakage levels, is often difficult to identify during inspection procedures and, therefore, could result in the smell of oil in the pressurized cabin when the aircraft is put in service. The only solution to completely preventing contaminated air from entering the cabin on aircraft using engine compressed air for pressurization and ventilation is to completely re-design the aircraft's system. And, that's not going to happen!