Re: in-flight engine shutdown / antiquated ATC equip

From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
Date:         02 May 95 13:27:41 
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>Sure it seems safe enough to fly an aircraft on one engine, but that
>one engine is now running at at least 200% of it's normal cruise power.

I doubt that's true.  An ETOPS rating of, say, 120-minutes, means 120
minutes from an alternate landing site at reduced performance, which
includes both slower speed and lower altitude.  There's going to be
some additional drag due to rudder input to counter yaw, but the
thrust increase required to compensate for the added drag won't be
that much.

Even at 200% of normal cruise power, the stress on the engine is not
as much as you might think -- at cruise, even a big fan only produces
a few thousand pounds of thrust, a small fraction of its rated power.
That means a lot of mechanical parts (bearings, for example) aren't
being stressed very much.

>I would think that the statistics used to say ETOPS are safe, are
>flawed.  They are based on the reliability of an engine in a twin
>engine set up.  Not a single engine at greater power.

Do you have any facts to substantiate those last two sentences?  I
seriously doubt you do.

Karl Swartz	|INet
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