Re: ETOPS

From:         Steve Lacker <slacker@arlut.utexas.edu>
Organization: applied research laboratories
Date:         03 Nov 96 19:56:57 
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C. Marin Faure wrote:

> The first jet engines were less reliable than the piston engines of the
> same era.

By "first jet engines" do you mean, for example, the J-57s of the 707? Or
do you literally mean the very earlyjets that were never used for passenger
service. If it is the former, I would like to hear more concrete evidence
that they were "less reliable" than a Wright 3350. You may well be right,
but it goes against EVERYthing I've read along those lines.

> They have steadily gotten more reliable until today engine
> failure can almost be ruled out as a potential problem, assuming proper
> maintenance and operational procedures, of course.

Again, "almost be ruled out" is a pretty strong term. I was shocked when
I first flipped through the NTSB report page
(http://www.ntsb.gov/Aviation/months.htm) to find a surprising number of
"uncontained engine failures." Most of these weren't losing whole fan
disks and killing people like the recent MD-88 or the Sioux City DC-10,
but most represent total engine failures nonetheless. Statistically, yes
its a small number of failures per number of flights... but in my book it
can't "almost be ruled out" until the total probability of such a failure
gets down to the "once in 10 years" sort of range. We aint there yet!

--
Stephen Lacker
Applied Research Laboratories, The University of Texas at Austin
PO Box 8029, Austin TX 78713-8029
512-835-3286	slacker@arlut.utexas.edu