PRIMUS
r
1000 Integrated Avionics System
A28--1146--112--00
A--7
AHZ--800 Attitude and Heading Reference System (AHRS)
OPERATION
Standard Operation
The standard AHRS operating modes are the normal mode for
attitude, and the MAG mode for heading. After the system is turned on,
AHRS enters these modes automatically, if all system components
and signals are valid. In the normal mode, true airspeed from the MADC
is used to compensate for acceleration--induced error sources inherent
to the vertical gyro system. In the MAG heading mode, the flux valve
is used to establish the magnetic heading reference. System operation
in this mode is similar to that of a conventional magnetic compass, that
is stabilized by a gyroscope.
In the MAG mode, when valid flux valve data is lost, a HDG flag is
displayed on the heading instruments. The HDG flag clears when the
DG mode is entered again.
when exiting the DG mode, the AHRS automatically synchronizes the
heading outputs to the present flux valve magnetic heading. This
feature can also be used if a heading error develops while in the slaved
mode. The error can be quickly removed by momentarily entering the
DG mode and returning to the slaved mode. This is done by selecting
DG mode with the MAG/DG switch.
NOTES:
1. In normal operation, no flux valve slaving annunciation
is displayed.
2. The pilot cannot fast--erect the AHRS. The system
constantly updates the vertical calculations.
The AHRS has two power source inputs. On the pilot’s side, the primary
and auxiliary power is from the left essential bus. On the copilot’s side,
the power is from the essential bus; auxiliary power is from the
emergency battery bus. Separate circuit breakers are used for each
power source. In flight power loads or bus switching, transients do not
shut down the AHRS because power is automatically transferred within
the AHRU to the auxiliary power input. When the primary power input
is restored, the AHRS switches back to the primary power source.
