L
-.
air supply cut off
to
the gyro and usually
takes about
10
minutes.
During Gyro spin down most gyros have a
tendency
to
"tilt" (precess) to one side.
If
the
air supply is reapplied
to
the gyro while in this
state, unusually slow gyro erection (leveling)
will occur.
If
aircraft operations are initiated
before the gyro is fully erected, there is a
greater possibility that the gyro may tumble
causing
loss
of primary attitude information
from the Attitude Gyro.
HEADING SELECTlPRESELECT
Mode
(HDG)
Select a desired heading by positioning
the heading "bug" on the PNI. This is done
with the HDG knob on the PNI.
Depress the HDG button on the Mode
Controller
to
activate the HDG mode. 'HDG"
will light on the Annunciator Panel and a
computed, visually displayed bank com-
mand is shown on the FCI. Following this
bank command, the aircraft will bank and roll
out on the desired preselected heading.
The Command V-bar on the FCI will de-
flect in the direction of the shortest turn to
satisfy the commanded turn of the pre-
selected heading. The aircraft may be man-
ually banked
to
realign the V-bar and satisfy
the command or,
if
the Autopilot is engaged,
the aircraft will automatically bank, turn
to,
rollout and hold the preselected heading. As
the aircraft approaches the selected head-
ing the V-bar will command a rollout
to
wtngs
level.
With the HDG mode in operat,ion. sub-
sequentchanges made in the heading "bug"
position on the
PNI
will immediately cause
the V-bar on the FCI
to
call for a turn
to
the
new heading, unless the HDG button on the
Mode Controller has been depressed again
to
cancel the HDG mode.
The HDG mode is cancelled when NAV
or APPR coupling occurs, or when FD mode
button is pushed
to
"OFF".
NOTE:
For system limitations refer
to
your
Flight Manual Supplement.
29
To Next Page
Loading...
