Piper ARCHER II - Section 7 - System Description; AFCS OVERVIEW; G5 Outputs to Autopilot; G3 X Outputs to Autopilot

SECTION 7 — SYSTEM DESCRIPTION
AFCS OVERVIEW
The
GFC
500
is
a
digital
Automatic
Flight
Contral
System
(AFCS).
It
is
a
two-axis
autopilot
and
flight
director
system
which
provides
the
pilot
with
the
following
features:
G5
Outputs
to
Autopilot
—
The
G5
flight
instrument
(when
installed)
provides
attitude,
rate,
and
acceleration
information
to
the
servos.
Additionally,
indicated
airspeed,
vertical
speed,
pressure
altitude
and
GPS
information
are
sent
to
the
autopilot
for
mode
control.
G3X Outputs to Autopilot — The G3X electronic flight instrument system provides attitude, rate, and
acceleration information to ihe servos. Additionally, indicated airspeed, vertical speed, pressure altitude and
GPS information are sent to the autopilot for mode control.
Flight
Director
(FD)
—
The
flight
director
processing
occurs
in
the
G5
or
G3X
instrument.
Selected
modes
for
the
flight
director
are
displayed
on
the
G5
or
G3X
autopilot
stalus
box.
The flight director provides:
e Command Bars showing pitch/roll guidance
e
Vertical
/
lateral
mode
selection
and
processing
Autopilot
(AP)
—
Autopilot
operation
occurs
within
the
pitch,
roll,
and
optional
pitch
trim
servo.
It
also
provides
servo
monitoring,
and
automatic
flight
control
in
response
to
flight
direclor
steering
commands,
attitude
and
rate
information,
and
airspeed.
Optional Electric Pitch Trim — The pitch trim servo provides manual electric pitch trim capability when the
aulopilot is not engaged. The trim servo provides automalic pitch trim when the autopilot is engaged and the
airplane is in the air. Automatic trim functionality is disabled on the ground.
GMC
507
—
Pilot
commands
to
the
autopilot
and
flight
director
are
entered through
the
GMC
507
autopilot
mode
panel,
The
GMC
507
contains
intemal
sensors
which
calculate
the
aircraft
attitude,
attitude
rate
and
accelerations.
These
inertial
sensors
are
completely
independent
from
the
sensors
within
the
G5
or
G3X
and
the
rest
of
the
autopilot
system,
and
are not
used
for
the
flight
director,
autopilot,
trim
or
ESP
functions.
They
are
used
Solely
lo
provide
independent
monitoring
of
the
GFC
500.
Airspeed and Altitude Information — The GFC 500 requires airspeed and altitude information from the G5
instrument or the G3X system.
Other
components
of
the
AFCS
include
the
GSA
28
pitch,
roll,
and
optional
pitch
trim
servo
that
also
contain
autopilot
processors,
contro!
wheel
mounted
elevator
trim
switch
(if
trim
servo
is
installed),
control
wheel
mounted
autopilot
disconnect
and
trim
interrupt
button
(AP
DISC
/
TRIM
INT),
and
a
Go-Around
(GA)
button.
Underspeed
Protection
(USP)
—
The
GFC
500
will
provide
Underspeed
Protection
when
the
autopitot
is
engaged.
When
the
minimum
airspeed
of
65
KIAS
(75
MPH)
is
reached,
a
visual
MINSPD
message
will
appear
above
the
airspeed
tape
and
the
autopilot
will
lower
the
nose
to
maintain
65
KIAS
(75
MPH).
An
aural
"AIRSPEED,
AIRSPEED’
voice
alert
will
sound
for
installations
connected
to
an
audio
panel.
Underspeed Protection Is inhibited when the airspeed exceeds 70 KIAS (80 MPH).
Overspeed
Protection
(OSP)
—
The
GFC
500
will
provide
Overspeed
Protection
when
the
autopilot
is
engaged
When
the
maximum
airspeed
of
140
KIAS
(160
MPH)
is
reached,
visual
MAXSPD
message
will
appear
above
the
airspeed
tape
and
the
autopilot
will
raise
the
nose
of
the
aircraft
to
avoid
exceeding
140
KIAS
(160
MPH).
An
aural
“AIRSPEED,
AIRSPEED’
voice
alert
will
sound
for
installations
connected
to
an
audio
panel.
Overspeed
Protection
is
inhibited
when
the
airspeed
is
below
135
KIAS
(155
MPH).
190-02291-07
Rev.
5
AFMS
—
GFC
500
Autopilot
in
Piper
PA-28
Series
Page
7-1