Hawker 800 XP, Pilot Training Manual

Page: 439 / 504

is subject to drift and turn error. For this rea-
son, AHRS operation in the "DG" mode results
in reduced heading accuracy.
While in the “DG” mode, the heading card
may be manually set to any heading using the
DG SLEW knob on the AHRS controller. The
control is inactive in the “Slaved” mode. Two
slew speeds are provided for each direction.
The SLOW slew position is located at the me-
chanical detent and is used for fine heading
card adjustments. The FAST slew position is
located at the mechanical limits of the control
knob and is used for large heading card ad-
justments. The knob will automatically cen-
ter to the OFF position when released.
Turning the knob clockwise causes the head-
ing card to indicate increasing headings. The
HDG flag on the EHSI will come into view ini-
tiating a slew command and will clear upon re-
leasing the control knob.
In the “Slaved” mode, a loss of valid flux
valve data will result in a HDG flag on the
heading instruments (EHSI and RMI) and the
illumination of the red SLAVE annunciator
on the AHRS controller. The HDG flag will
clear upon subsequent entry to the DG mode,
but the SLAVE annunciator will remain lit
(Figure 16A-5).
Upon exit from the “HDG” mode, the AHRS
performs an automatic synchronization of the
heading outputs to the present flux valve mag-
netic heading. This feature may also be used
if a heading error should develop, while in
the “Slaved” mode. The error may be quickly
removed by momentarily entering the “IDG”
mode and returning to the “Slaved” mode.
This is performed by pressing the HDG/DG
pushbutton on the AHRS controller twice.
In the “Slaved” mode the difference between
the indicated heading and the flux valve head-
ing is displayed on the Slave Error Indicator
(Heading Sync Indicator) located on the EHSI.
The card has two symbols: a cross ("+") and
a dot (“o”). The cross (“+”) and dot (“o”) are
displayed in a fixed position with a moveable
pointer on the EHSI.
During straight and level flight the Slave
Error Indicator will generally be centered
with excursions toward the cross or dot oc-
curring over a 20 to 30 second time period.
Revision 1 16A-15
FOR TRAINING PURPOSES ONLY
HAWKER 800 XP PILOT TRAINING MANUAL
FlightSafety
international
FAST FAST
SLOW SLOW
OFF
DG SLEW
HDG
DG
VG
ERECT
DG FAST AUX PR
SLAVE BASIC
TEST
x
Figure 16A-3. AHRS Controller
Figure 16A-4. ADI with “ATT” Comparator
Figure 16A-5. HSI with “HDG” Flag