Re: ETOPS Question

Date:         03 Oct 97 01:18:34 
From:         Exiled Expat <lutsch@emirates.net.ae>
Organization: Emirates Internet
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C. Marin Faure wrote:
> > On modern jetliners, if one engine fails during cruise, is the remaining
> > engine really used to the max ?

>   Unlike a turbofan engine, the
> chance of failure in a piston engine increases steeply with power.  As
> long as you don't overtemp it, a turbine could care less what power
> setting you run it at or for how long.

Sorry But this statement is not entirely correct, as turbine disks and blades
are sensitive to higher than normal rotational speeds that can cause blade
creep resulting in blade tip rubbing on the outer case seal, Blade root
cracking and just generaly trashing itself as the speed increases above its
design point.  This failure is more likely the higher the Exhaust Gas
Temperature ( EGT ) but a catastrophic failure can result nonetheless at a
very low egt if the rotor RPM is too high.

All turbine engine fuel control units that I have ever worked with have built
in fuel schedules to prevent overspeeds and the Rolls Royce RB211 series had
engine shutdown protections built in to prevent the turbine from flying apart
if its shaft should break As does the new Trent series.

Regards,
Hans Lutsch