Re: Can an Airbus 320/321/330/340 perform a controlled glide?

Date:         15 Apr 97 12:56:42 
From: (Robert Dorsett)
Organization: Netcom Online Communications Services (408-241-9760 login: guest)
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In article <airliners.1997.903@ohare.Chicago.COM> Pete Mellor <> writes:
>In the event of loss of all 5 computers in the Electrical Flight
>Control System (EFCS) the crew can control pitch by moving the
>Trimmable Horizontal Stabiliser (THS) using the pitch trim
>wheels, and yaw (and roll to some extent) by operating the rudder
>via the pedals. Connection to both of these surfaces is mechanical

A minor quibble.  These "mechanical" linkages lead to hydraulic actuators.
There is no "stick-to-surface" reversion mode.  This is different from the
normal modes of operation, which use electrical signals which have first
been processed by computers to command the hydraulic actuators.

In this respect, the "fly-by-wire" merely replaces the control cable
linkages found in non-FBW aircraft, and none of the hydraulic plumbing.

Other small airplanes, such as the 727 or 737, have true "manual reversion"
capabilities, in which the control cables signal control tabs, which
aerodynamically position the control surfaces.  This results in heavy
and mushy controls, but does provide a credible "get it on the ground"
capability in the event of complete hydraulic failure.

Most modern aircraft, particularly large airplanes, are purely hydraulic.
If you lose all hydraulic systems, you pretty much die.

Robert Dorsett                         Moderator, sci.aeronautics.simulation