Originally Posted by
DaveReidUK
Isn't the argument about exposure to OPs in bleed air, not about combustion products ?
If you look at how jet engines work, with differential pressures across all seals (driving any contaminants
away from the gas path, even if seals leak), and from where bleed air is taken (before fuel is introduced), you will find that if anything other than outside air enters the bleed air path, something has gone
seriously wrong with the engine. In all normal and halfway normal and even most abnormal operating conditions there is no way for oil, fuel or combustion products to enter the bleed air.
That is not to say that toxic substances can never enter cabin air systems, in fact there are many credible reports that that has happened, including a lengthy
German study (in German, I'm not sure it has been translated), but the engine is unlikely to be the source.
Bernd