SIRS NAVIGATION LTD
COMPONENT MAINTENANCE MANUAL
C. Removal of Mechanical Alignment Error (index error).
1. Move the aircraft to magnetic heading: North, South, East and West.
Aircraft Magnetic
Heading
Standby Compass
Error
North 0
°
East 90
°
South 180
°
West 270
°
2. Write the compass indications in the STANDBY COMPASS column.
NOTE: The compass must be stable before you write the indications in the table.
3. Write the results in the ERROR colum.
4. Do the algebraic sum of the four errors in the ERROR column and divide the result
by four.
NOTE: Example:
NORTH –3, EAST –2, SOUTH +7, WEST +8
-3+(-2)+7+8=10
10
÷
4=2.5
Index Error = 2.5
5. Do the adjustment for the index error as follows:
(a) Make a mark on the aircraft mounting bracket that is in line with the centre
index mark of the compass mounting plate.
(b) Loosen the screws that attach the compass to the mounting bracket.
(c) Turn the compass to make an allowance for the index error.
NOTE: If the index error is positive, move the compass clockwise. If the
error is negative, turn the compass counterclockwise.
(d) Tighten the screws that attach the compass to the mounting bracket.
PAGE 11002
APR 10/03
34-25-21
The document reference is online, please check the correspondence between the online documentation and the printed version.
