SIRS NAVIGATION LTD
COMPONENT MAINTENANCE MANUAL
(iii) Slow Movement of the Compass Card
The compass card will move slowly during aircraft direction changes
and the card can become fixed
.
Follow the procedure below if the
compass card has slow movement.
a) Remove the compass from the aircraft.
b) Put the compass on a non-magnetic stand or table in an area away
from magnetic disturbances.
c) Align the compass to magnetic North.
d)
Deflect the compass card from the North heading by +5
°
, with the
use of a small magnet and let the card to stop.
e)
Remove the magnet and monitor the compass card movement.
The card must return to 1 degree of the North heading.
f)
Deflect the compass card from the North heading by -5
°
, and let
the card to stop.
g)
Remove the magnet and monitor the compass card movement.
The card must return to 1 degree of the North heading.
h) Follow the procedure detailed in paragraphs d) to g) for East,
South and West headings.
i) The compass must be repaired or replaced if it fails to return to 1
degree of each heading.
(iv) Fluid Loss / Air Bubble
An air bubble will be seen in the fluid of the compass. It is not normal
for fluid to be seen on the outside surface of the compass.
A small bubble does not make the compass unserviceable, but the
compass must be repaired or replaced in a short time.
A large air bubble will make the compass inaccurate. The compass
must be repaired or replaced immediately.
(v) Magnetic Correction Problems
This problem will be identified when the compass has been installed in
the aircraft and during the 'aircraft swing' procedure.
The magnetic error of the compass, caused by the aircraft, will not be
easy to remove.
PAGE 1003
APR 10/03
34-25-21
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