James wrote in
:



Bertie the Bunyip wrote:
Robert Moore wrote in
5.205:


Bertie the Bunyip wrote

The next generation are eschewing bleed air driven pressurisation
and going to seperate supercharger systems. A lot of older
turboprops used this system as well as a small number of jets. The
787 will have this system.

The B-707 had both Bleed Air and Turbochargers. We used the
Turbochargers most of the time. An engine bleed line spun a turbine
which then turned a fresh outside air compressor.


Yeah, that was the jet exception I had noted. You were lucky you
didn't have to breath the compresser section air in that thing!
The JT8 was OK AFAIK There would have been some fumes, but the
RB-211 is a complete piece of junk. The Brits never could build an
oil tight engine....

Thats why you never change the oil in a british engine, you just
change the filter every 6000 miles, with the leak and replace of the
oil, oil changes are just a waste of time.



True, and they actually don't change the oils in RB 211s either! That is
part of the problem. As jet oil ages it gets thinner and leaks more
easily, and it also gets smellier.




Bertie