Aircraft Cabin Air and Engine Oil - An Engineering View
Author: Dieter Scholz
Paper published in the Journal of Health and Pollution, Vol. 9, No. 24 (December 2019), pp. 93–98. https://doi.org/10.5281/zenodo.3565835
on the occasion of the International Aircraft Cabin Air Conference 2017, Imperial College London, 19 - 20 September 2017
This is a document from the project Aircraft Cabin Air.
Almost all passenger jet aircraft today use potentially contaminated bleed air for cabin ventilation.
A detailed look at the design of engine bearings, their lubrication and sealing reveals that jet
engines leak small amounts of oil by design and not only in failure cases. An equation is derived to
calculate the concentration of a possible cabin air contamination. The seal leak ratio is defined as
the percentage of oil leaving engine seals versus total engine oil consumption. If the seal leak ratio
is set to 2%, results show good agreement with measured concentrations of hydrocarbons in aircraft
cabins under normal conditions. The solution to the problem of cabin air contamination is a bleed
free design. Other partial remedies are briefly discussed.