Flight director valid is comprised
. CPU “A” heartbeat monitor valid
of
the following:
which Drovides validity
logic to engage/disengage the autopilot functions. Th~
heartbeat monitor is hardware independent from the CPU,
so that no single fault can disable both the
CPU and the
monitor.
The heartbeat monitor output is provided as an
interrupt to the nonmonitored processor.
● Flight director flag/annunciator valid which is a direct
discreet output from the “A” CPU to drive the FD flag on
the PFD and enable the annunciator drivers on the same
side guidance controller channel.
. FGC power supply valid which monitors the internal
power
supply voltages for proper operating levels.
3. B. (7) (g) Z Lateral Steering Command with Autopi1ot Engaged
With the autopilot engaged, the selected flight director
steering command is routed through the:
. Rate Limiter
. Bank Angle Limiter
s Roll Hold Switch
● First Summation Point
. Second Summation Point
From the second summation point, the steering command is
rate limited again, acceleration and bank angle limited, and
then split into two paths.
The first path goes up through
the activated AP ENG switch, the roll bar bias switch and
then to the symbol generator.
The second path routes the steering command to a M degrees
position command limiter,
is gain adjusted and applied to a
pulse width command limiter and output servo amplifier.
The pulse width command limiter serves two functions.
First, it is the D/A converter for the servo amplifier.
Second, as a motor driver it issues a continuous string of
28 V dc pulses, at a rate of one pulse approximately every
2 milliseconds. The pulse width of the pulses is determined
by the lateral command.
The pulse width command limiter has
its current limits established by a software program
contained in the “B” CPU.
The output of the servo amplifier is sent to the SM-600
aileron servo drive motor and to the “A” processor current
monitor to check for servo runaway current. The SM-600 is a
permanent magnet dc motor that utilizes a dc tachometer for
rate feedback. It has but does not use a position feedback
synchro. As the servo motor drives to position the aileron,
22-14-00
Page 298.97
Aug 15/91
Use or disclosure of information on this page IS subject to the restrictions on the title page of this document.
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