__________________________________________________________________
Cirrus Perspective™ Line Maintenance Manual
Page 7-35
190-00920-00
Rev.
E
7.4.3.2
Procedure
B:
GMU
44
Magnetometer
Calibration
Procedure
The
Magnetometer
Calibration
Procedure
must
be
carried
out
at
a
site
that
is
free
of
magnetic
disturbances.
A
site
evaluation
for
magnetic
disturbances
can
be
performed
for
the
magnetometer
calibration
procedure
if
a
compass
rose
is
not
available.
The
accuracy
of
the
GRS
77
and
GMU
44
cannot
be
guaranteed
if
this
calibration
is
not
performed
in
a
magnetically
clean
area.
NOTE
Typically,
a
compass
rose
is
an
acceptable
location
to
perform
the
magnetometer
calibration
procedure.
However,
because
not
all
compass
roses
are
well
maintained,
even
an
existing
compass
rose
should
be
regularly
evaluated
using
the
method
described
here
to
determine
if
it
is
free
of
magnetic
disturbances.
If
evaluation
of
an
existing
compass
rose
indicates
that
magnetic
disturbances
are
present,
then
an
alternative
location
must
be
found
to
perform
the
procedure.
A
Perspective™
System
equipped
aircraft
can
be
used
to
evaluate
a
candidate
site
for
magnetic
disturbances
and
determine
whether
it
is
a
suitable
location
to
perform
the
magnetometer
calibration
procedure.
The
magnetometer
calibration
procedure
itself
contains
the
logic
to
simultaneously
survey
the
location
for
magnetic
cleanliness
while
it
is
computing
the
magnetometer
calibration
parameters.
The
Perspective
equipped
aircraft
used
to
evaluate
the
site
must
have
already
completed
the
pitch/roll
offset
compensation
procedure
(Procedure
A).
However,
prior
completion
of
the
magnetometer
calibration
procedure
(Procedure
B)
is
not
required.
In
order
to
evaluate
a
candidate
site,
the
magnetometer
calibration
procedure
must
be
performed
twice:
once
turning
clockwise
around
the
site,
and
once
turning
counter
‐
clockwise.
Both
times,
the
procedure
should
be
conducted
with
the
exception
of
the
direction
of
turns
around
the
site.
NOTE
Although
the
procedure
should
be
performed
by
making
a
series
of
clockwise
turns
around
the
site,
the
procedure
can
also
be
performed
by
making
counter
‐
clockwise
turns
for
evaluating
the
site
for
magnetic
disturbances.
If,
upon
completion
of
the
Magnetometer
Calibration
Procedure
in
each
clockwise
and
counter
‐
clockwise
direction,
the
PFD
displays
the
“CALIBRATION
SUCCESSFUL
/
SITE
IS
CLEAN”
message,
then
the
candidate
site
is
sufficiently
free
of
magnetic
disturbances
and
is
acceptable
for
performing
the
procedure.
It
is
important
to
obtain
successful
results
in
both
the
clockwise
and
counter
‐
clockwise
directions
to
ensure
that
the
magnetometer
sweeps
over
a
large
enough
area
in
the
candidate
site.
Summary of Contents for Cirrus Perspective SR20
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