Re: A320 pitch control (was: emergency procedure)

Date:         18 Apr 98 00:49:28 
From:         Pete Mellor <pm@csr.city.ac.uk>
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Julian,

It would take a *long* time to list all of the provisions of
the laws! (My source was my copy of the A320 FCOM, which I
*think* I interpreted correctly!)

To start from the bottom of your message:-

> Normal law: stick deflection controls lift, with maximum stick deflection
> corresponding to maximum permissible AOA (or is the AOA protected in a
> different way?)

Normal law is a "load factor demand" law. The "load factor" (G) is
proportional to stick deflection. With stick at neutral, the
system maintains 1G in pitch. In turns, no pitch correction is
required once the turn is established.

In addition, there are many protections, of which a limit on AOA
is just one.

On top of that, the law has different "modes" for different phases
of flight (ground, flight, flare, ground).

> Alternate law: stick deflection controls lift, with maximum stick deflection
> corresponding to maximum permissible loading

Same as normal law, without some of the protections.

> Direct law: direct relation between elevator deflection and stick position,
> with maximum stick defelection corresponding to maximum elev deflection

Basically correct, except that the FCOM states "with full authority"
rather than stating what the maximum stick deflection corresponds to.
(The max. surface deflection depends on CoG and configuration, but
other than that, there are *no* protections.)

There's *much* more than that, but I don't have time right now to
type out a whole section of the FCOM! :-)

Regards,

Pete