Re: 757-300?

From: (Terrell D. Drinkard)
Organization: Boeing
Date:         31 Mar 93 01:14:49 PST
References:   1 2 3
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In article <airliners.1993.271@ohare.Chicago.COM> (Christopher Davis) writes:
>HAC> == H. Andrew Chuang <>
>KS>  == Karl Swartz <kls@ohare.Chicago.COM>
>Arguably, the 737-500 is a shortening of the -300; yes, yes, I *know* it's
>the same size as the -200, but it's in the "new generation" 737 series.

The -500 is really a 58" stretch of the -200, which itself was a stretch of
the -100 (32 built).

>Certainly that model seems to be doing well (or maybe it's just that
>Southwest is buying them all :).

Actually, Southwest buys the -300 exclusively.  Without EFIS I might add.

> HAC> However, this will be feasible only if a derated PW2000 or RB211-535
> HAC> is available.

Or a CFM56-5, or an IAE V2500.

> KS> There really does seem to be a gap in engine offerings here.
>True.  But if a derated engine did become available, wouldn't it have
>really good MTBF numbers?  (Isn't that one of the big advantages of
>derating?)  This would imply that a theoretical 757-100 with, say, derated
>RB211s would have the dispatch reliability and time-between-maintenance to
>serve in many of the current 727 "feeder" and "shuttle" roles.  (But can it
>land at LGA?  If so, other advantages, especially with derating, could
>include quieter engines and faster [therefore noise-abating] takeoffs.)

Derating does give better engine maintenance costs, longer engine life,
etc.  The rate of increase is less than the rate of increase in extra fuel
burned to haul around all that extra engine capability that isn't used.
Besides, you will find that most of the 757s mechanical dispatch
reliability problems stems from the navigation boxes, not the engines.  At
any rate, it is already as good as, or better than a 727-anything. (Yes it
can land at LaGuardia - it can land anywhere a 737 can)  Derating the
engine does not help with noise.  Lighter takeoff weights do.  

> KS> (Seriously, it's good to see someone from one of the engine
> KS> manufacturers contributing to the group.  Welcome!)
>Agreed; the amount of real expertise here (both professional and `amateur')
>is incredible.  I think a great deal of the thanks must go to our moderator
>as well (and I'm not just saying this so he'll post my message :)

I'll add my welcome, too!  Hope you guys make lots of money...  :-)

>(Note also that I am *not* a real expert of either type, so I can't claim
>that what I've said about derated engines is correct.  But I hope to be
>corrected by those who *do* know, and learn therefrom.)

I'm not a specialist either, but my job does require a certain familiarity
with all the stuff discussed above.  And we just went through a lot of this
recently.  :-)

"Anyone who thinks they can hold the company responsible for what I say has
more lawyers than sense."