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KCS 55A Compass System
Under some conditions it is possi-
ble for the system to stop slaving
exactly 180 degrees from the cor-
rect heading. If this should occur,
move the "Slave" switch on the
KA 51B to the unslaved (free)
position. Rotate the compass card
±10 degrees from the incorrect
heading by using the manual rota-
tion switch and then return the
system to slaved operation. The
system will then slave to the cor-
rect heading.
4. For the free gyro operation, check
the magnetic compass to deter-
mine the correct magnetic head-
ing. Then use the manual slave
switch to align the system with the
earth's magnetic field. Periodic
checks with the standby compass
are recommended to check and
correct for gyro precession.
5. Until a usable navigation signal is
being received by the NAV sys-
tem, a red flag labeled "NAV" will
be visible in the upper left quad-
rant of the KI 525A Indicator. In
operation, this warning flag should
be visible whenever an inade-
quate navigation signal is being
received.
6. For normal navigation to or from a
VOR or VORTAC, set the NAV
receiver to the desired VOR or
VORTAC frequency and the red
navigation flag (NAV) should dis-
appear from view if a usable sig-
nal is being received.
7. Rotate the course select knob to
position the course pointer to the
desired VOR course.
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KFC 225 AUTOMATIC FLIGHT CONTROL SYSTEM
8. The VOR deviation bar represents
the selected course, and the rela-
tionship of this bar to the symbolic
aircraft in the center of the instru-
ment visually presents the actual
relationship of the selected course
to your aircraft heading. (In other
words, if the symbolic aircraft on
the display indicates approaching
the deviation bar at 45 degrees,
that is the angle at which your air-
craft is actually approaching the
selected course.
9. To prepare for an ILS approach,
tune the NAV receiver to the
desired Localizer frequency. If a
usable Localizer signal is being
received, the NAV warning flag
will disappear.
10. For a front or back course
approach, rotate the course select
knob to set the course pointer on
the inbound Localizer course. As
with normal navigation (#6 above),
the LOC deviation bar represents
the desired course. The relation-
ship between this bar and the
symbolic aircraft gives a true pic-
ture of your aircraft's position with
respect to the Localizer course.
Always setting the course pointer
to the inbound Localizer course
provides the correct deviation bar
sensing whether flying a front or
back course approach.
11. The glideslope deviation pointers
should become visible on both
sides of the display when a usable
glideslope signal is received. If
they do not come into view, a
usable glideslope signal is not
being received.
Rev. 0
Apr/99
12. The glideslope pointers indicate
the relative position of the glides-
lope path with respect to the air-
craft. (In other words, if the point-
ers are above the center marker,
the aircraft is below the glides-
lope.)
Abnormal Circumstances
If the Warning Flag (HDG)
appears during operation, the com-
pass card indications will be in error.
Power may be removed from the KG
102A Directional Gyro by pulling the
appropriate circuit breaker. The
Selected
Course,
VOR/LOC
Deviation Bar, the NAV flag, and the
To/From Indicator will remain in
operation.
If the Navigation Warning Flag
(NAV) appears during operation,
there are several possibilities: (1) the
NAV receiver is not turned on, (2)
the NAV receiver is improperly
tuned, (3) the ground VOR or LOC
station is malfunctioning, (4) the air-
craft is out of range of the selected
ground station, or (5) the aircraft
NAV receiver has malfunctioned.
(The compass card will continue to
display the aircraft heading even if a
usable NAV signal is not being
received.
If the glideslope pointers
remain out of view during a front
course ILS approach, wither the air-
craft glideslope receiver or the
ground station glideslope transmitter
is malfunctioning. Glideslope is usu-
ally not available during a back
course approach. (The VOR and
LOC course display will continue to
Rev. 0
KFC 225 AUTOMATIC FLIGHT CONTROL SYSTEM
Apr/99
KCS 55A Compass System
function normally even if a usable
glideslope signal is not being
received.)
A continuous large deflection of
the slaving meter or large discrepan-
cies between the magnetic compass
and the KI 525A compass card may
indicate a failure in the slaving sys-
tem. If a slaving failure should occur,
the Slave/Free Switch should be
moved to select the free gyro mode.
Then, by using manual clockwise or
counterclockwise corrections, the
compass can be rotated to the cor-
rect heading as indicated on the
standby compass. The KCS 55A
system should continue to function
normally except the heading infor-
mation will be solely derived from the
KG 102A Directional Gyro. There will
be no automatic heading correction
and periodic adjustments must be
made manually to correct for preces-
sion by reference to the standby
magnetic compass, as with any
directional gyro.
Note: It is desirable to disconnect
the autopilot under the following
conditions:
1. HDG flag comes into view.
2. System is in fast slave.
3. During manual slaving.
The system has the capability
to supply the autopilot with an auto-
matic disconnect signal under these
conditions.
Note: For system limitations in your
particular aircraft type, refer to your
Flight Manual Supplement.
33
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