Textron Cessna 172R, Pilot Operating Handbook, Page: 445 / 500

CESSNA
MODEL
172R
SECTION
9
-
SUPPLEMENTS
SUPPLEMENT 15
-
FAA APPROVED
3.
Flashing GS
--
Indication of a flagged glideslope. (GS will
rearm automatically if a valid
GS
signal is
received.)
NOTE
To continue tracking the localizer, observe the
appropriate minimums
for
a nonprecision
approach.
(Press
ALT twice in rapid succession
to terminate the
flashing. Control the pitch axis in the
default VS mode.)
NOTE
At the
onset
of mode annunciator flashing, the autopilot
has already reverted
to
a default mode
of
operation, i.e.,
ROL and
or VS mode.
An immediate
attempt to
reengage
to
lost mode may be made
if the offending
navigation, glideslope or compass
flag
has cleared.
EXCEPTION
The HDG annunciation will flash for 5
seconds upon
selection of NAV, APR, or REV modes
to
remind the
pilot
to set
the
HDG
bug for use
as course datum.
Effects of instrument losses
upon
autopilot operation:
1
.
Loss
of
the
artificial
horizon
--
no effect on the autopilot.
2. Loss of the
turn
coordinator
--
autopilot inoperative.
3.
Loss of the Directional Gyro (DG)-- The directional gyro
does
not
provide any
system
valid flag. If the DG fails
to
function
properly the autopilot heading and navigation
mode will
not
function correctly. Under these conditions, the only
usable
lateral mode is ROL.
4.
Loss of Horizontal Situation Indicator
(HSI) (if installed)
--
If
the HSI fails
to
function properly the autopilot heading and
navigation mode will
not
function correctly. Under these
conditions, the only usable lateral mode is
ROL.
5.
Loss
of Blind
Altitude Encoder
--
Altitude Alerter and Altitude
Preselect function inoperative.
Original Issue S15-19
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