System Safety
Is
Assured
By
Integrity Monitors
The KFC 250 monitors the validity of the
system sensors and the Flight Computer
to
alert the pilot when the system cannot res-
pond correctly
to
command signals
Invalid” signals provide visual warvlng
by means of the flags and annunciators In-
valid” signals are also routed
to
the KFC 250
switching logic
to
“lock out” modes which will
not operate reliably
Most failures in the slaved compass
system would be annunciated by a compass
flag and the system would not allow selection
of the Heading, NAV or APPR modes
The illustrations above show the KFC 250
Flight Director cockpit displays with all warn-
ing flags in view
Flight Command indicator warnings:
Flight Director (FD) Command V-bar will bias
out of view whenever the FD mode is not
selected, and when FD internal power is in-
adequate Attitude and computer flags will
also be in view
The Pictorial Navigation Indicator
warnings: A compass flag indicates that the
compass card is not displaying proper heading
A NAV flag indicates that a valid NAV Signal is
not being received
12
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When an ILS channel is selected on the
NAV receiver and a valid Glideslope signal is
received, the Glideslope pointer will appear.
Glideslope coupling usually occurs at Outer
Marker, when the Glideslope is intercepted
(glideslope pointers centered) and APPR
CPLD. If, after GS coupling, the GS pointer
disappears, the system will flash the GS An-
nunciator and go from GS coupled
to
Pitch
Attitude Hold.
If
the GS pointer reappears,
the system will revert back
to
GS
coupled.
The NAV warning flag indicates an invalid
Localizer but has no effect on Glideslope
operation.
In the Approach mode, in an aircraft
equipped with dual
LOC
and GS receivers, Ap-
proach monitoring is provided if both systems
are tuned
to
the LOC frequency.
If
the devia-
tions of No. 2
LOC
or GS differs greater than a
preset amount the appropriate annunciator
light (APPR or GS) will flash.
The Trim warning light in the Annun-
ciator Panel will light when a monitored Auto
or Manual electric trim failure occurs or when
the trim breaker is pulled.
It
will also flash
4
to
6
times when the TEST switch on the Mode
Controller is depressed.
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