Originally Posted by
LarryJ
It comes from the compressor section of the engine which us up-stream of the combustion.
I still smell jet fuel when the 737 starts the engines after pushback.
Air still passes through the engine, where engine oil contamination is a possibility.
I am not saying that the air is contaminated on all bleed air systems, but it makes me feel a lot better knowing that air does not go through the engine.