Re: Engines CAN jettison (Was Rear engined aircraft. (727 DC9 MD80) )

From:         T.E.Thacker.Junior@lesueloc.com
Organization: Performance Systems Int'l
Date:         15 Dec 94 05:17:37 
References:   1
Followups:    1 2
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In article <airliners.1994.1761@ohare.Chicago.COM>, 
<d_peters@uoft02.utoledo.edu> writes:

> >No, airlines cannot jettison engines in flight.  In fact, it usually takes
> >a shift or two to change an engine, there are a lot of complex connections
> >between the airframe and the engine - electrical, hydraulic, pneumatic, and
> >structural.

  The pilots can't purposely select to jettison an engine but they *CAN*
be jettisoned:

(1) They are designed in a ditching situation to shear off and flip over
    the top of the wing rather than dig into the water & pull the wing off.

(2) In case of a nasty bad engine fire that is out of control the engine
    can jettison itself (which happened once on a B747 flight). I don't
    know how this is triggered (or suppressed) but I know of at least one
    false jettison (reported in the press as an engine "falling off").

(3) The DC-10 crash in Chicago in the late '70s (that resulted in the
    grounding of all DC-10's) was because an overstressed connection
    caused a premature jettison of an engine that flipped over the wing
    because it was under thrust & was designed to come off that way.
    The engine jettison caused hydraulic disruptions that deployed a
    spoiler which the pilot didn't recognize & retract. Coupled with
    not reducing climb rate, both contributed to the crash.