BendixKing SG 465 System EFS 50 - Manual (Page 75)

EHSI Displays
4.1.9 Issued 4/95 SW 06/07/08/11
verted to MAGNETIC reference.
If the compass card is TRUE ref-
erenced, MAGNETIC bearing
sensor pointers, such as VOR
and ADF, may be displayed if
valid mag var (magnetic varia-
tion) is provided to the EFS 50.
In this case, the MAGNETIC
sourced bearing pointer informa-
tion will be converted to TRUE
reference.
In most cases mag var is provid-
ed by an LNAV. In a single
LNAV installation the EFS 50 will
use the single mag var source to
compute display correction for
both number 1 and number 2
sensors. In dual LNAV installa-
tions, the on-side source of mag
var will be used to compute cor-
rection unless the cross-side
source is selected as the primary
NAV source; then its mag var will
be used.
If mag var becomes invalid,
those bearing pointers displayed
with mag var correction will be
removed and a RED X is drawn
through the sensor annunciator
in the lower right or left corner.
In the event a heading failure
occurs, a heading flag will be dis-
played to the pilot, the compass
card will remain active to follow
input form the compass system.
Bearing pointer information will
continue to be displayed. The
EFS 50 will process the bearing
information and present all bear-
ing pointer information except
ADF referenced to the compass
card, the ADF bearing pointer will
be relative to the nose of the air-
craft and lubber line on the EHSI.
EXAMPLE:
NOTE: Refer to figure 4.1.4
BEARING POINTER OPERA-
TION WITH LOSS OF HEAD-
ING when reviewing this
example.
Aircraft actual mag heading is
030 degrees, but EHSI com-
pass is failed and displays an
incorrect heading of 090
degrees — 60 degrees greater
than actual. Bearing pointer
number one is referenced to a
VOR station and is pointing to
120 degrees on the compass
card. Bearing pointer number
two is referenced to an ADF
station and is pointing to 180
degrees on the compass card.
When interpreting bearing
pointer number one in this
example, remember that VOR,
TCN, RNV, FMS, LOR or GPS
indications are referenced to
the compass card. Therefore,
since bearing pointer number
one is pointing to 120 degrees
on the compass card, the cor-
rect course to the VOR is 120
degrees. Likewise, since the
tail of bearing pointer number
one is on the 300-degree mark
on the compass card, the cor-
rect bearing from the VOR is
300 degrees.
Caution: Do not assume that
the course to the VOR is 30
degrees to the right of the aircraft
nose. Although the bearing